Table of Contents
The MISOSYS Relocating Macro Assembler product is published by: MISOSYS,
Inc., P. O. Box 239, Sterling, Virginia 22170-0239 [703-450-4181]
FIXUP/CMD - Copyright 1985 MISOSYS, Inc., All rights reserved.
MLIB/CMD - Copyright 1983/85 Richard N. Deglin, All rights reserved.
MLINK/CMD - Copyright 1985 MISOSYS, Inc., All rights reserved.
MRAS/CMD - Copyright 1985 MISOSYS, Inc., All rights reserved.
SAID/CMD - Copyright 1984 Karl A. Hessinger, All rights reserved.
SAIDINS/CMD - Copyright 1984 Karl A. Hessinger, All rights reserved.
XREF/CMD - Copyright 1983/84 MISOSYS, Inc., All rights reserved.
LDOS is a trademark of Logical Systems, Inc.
MICROSOFT is a trademark of the Microsoft Corp.
TRSDOS is a trademark of Tandy Corp.
MRAS was designed to provide the maximum in assembly power. As such, it is an
advanced tool which is not recommended for the novice Z-80 assembly language
programmer. This user manual is not a "learning" manual -- it details the use
of MRAS and its companion utilities -- and in no way attempts to teach you how
to program in the Z-80 assembly language. You should have available a standard
reference handbook on the Z-80 code. Many texts are available.
The MISOSYS Relocatable Macro Assembler Development System includes:
Source files commonly used with other assemblers take one of three forms; a
pure ASCII text file, a line-numbered text file, or a line numbered file which
includes a header. MRAS will automatically accept any of the three types for
its input provided all files included in one source stream use the same
convention. On the other hand, headered and numbered source files would be
found unworkable with the SAID text editor. Thus, a utility called FIXUP has
been provided. FIXUP allows you to change from one form to any of the other
forms. FIXUP requires a properly terminated file. Its syntax is:
The Model I/III MRAS Development system works on both the Model I and Model
III under LDOS 5.x, DOSPLUS 3.5, TRSDOS 2.3, and TRSDOS 1.3. It is released on
a 35-track single density data diskette. TRSDOS 1.3 users must use the CONVERT
utility and a two-drive system to transfer the files from the master disk to a
working system disk. Model I TRSDOS 2.3 users need to first modify their
TRSDOS system via a one-byte patch prior to transferring the files from the
master disk to a working system disk (see below). The master disk is readable
by LDOS and DOSPLUS. Model I or III use under a DOS other than LDOS may
require patches to one or more of the supplied programs.
Method (1) directly modifies the system diskette with a patch. To prepare for
this patch, obtain a fresh BACKUP of your TRSDOS 2.3 to use for this
operation. Then enter the following BASIC program and RUN it. After you RUN
the program, re-BOOT your TRSDOS diskette to correct the byte in memory.
If you are using other than 11" form paper, use the LINES parameter to alter
the paging parameters to suit the specifications of your printer. Note that
MRAS does not count characters per line!
The "+" indicator denoting a macro expansion will appear after the stream line
number. The address will be suffixed with a mode indicator which indicates the
current mode of the assembly source. The 16-bit operand will be suffixed with
a mode indicator which indicates the mode of the operand. The symbol table
will include a mode indicator following the value of each symbol. The
indicators are as follows:
The statement line is considered to be freely formatted. That means that there
are no columnar restrictions. Fields are separated by one or more tabs or
spaces. If a tab is used, it makes for neater listings. Tabs are also retained
as tabs and thus will keep source files smaller than using multiple spaces. A
statement line must not exceed 128 characters in length; thus, if a carriage
return is not detected by the 129th character, a "Load file format error" will
be generated.
A label may contain, within character positions 2-15, letters (A-Z), decimal
digits (0-9), or certain special characters: the at sign, "@"; the underline,
"_"; the question mark, "?"; or the dollar sign, "$". The dollar sign "$",
appearing by itself, is reserved for the value of the reference counter of the
current instruction. It cannot be used as a single character symbol.
A symbol appearing by itself in the LABEL field of a line, will be interpreted
as being equated to the current value of the program counter. Thus, the
following two LABEL examples are completely equivalent:
A value in parentheses "()" specifies indirect addressing when used with
registers, or "contents of" otherwise.
Constants are data declarations of fixed value. They are constructed as a
sequence of one or more digits and an optional radix specification character.
The digits must be valid for the radix used. The following table denotes
acceptable constant composition:
Operands may also be constructed as complicated expressions using the
mathematical and logical operators. These are described in the section on
"Expressions".
The pseudo-OPs DM, DEFB, and DEFM can be used in lieu of "DB" and are
completely equivalent.
"DB" string arguments permit two connected single-quotes to indicate a
single-quote value PROVIDED that two or more characters precede the 2-quote
appearance in the string. For example:
The following are valid declaration statements:
The "quantity" must range from 1 to 65535 (a zero value will result in 65536).
The "value" must be less than 256. With this pseudo-OP, you can generate
repetitions of a single constant. For example, say you want to set 100 storage
locations to a zero value during the assembly. Insert the statement,
The expansions of the constant will appear in listings just as they do in the
DB expansion. The expansions may be suppressed from your listings by using the
assembler switch, -NE.
The quantity, "nn", can be a data value or an expression. Note that "DS" does
not define data values. "DS" adds the quantity of storage locations reserved
to the current program counter (PC) to calculate a new PC value. When
generating a CMD object code file, this action will cause the next assembled
byte to create a new load record. When generating a REL object code file, this
action will generate a Set Location Counter special link item.
The statement,
If your source code is being assembled with the "-CI" switch, MRAS
automatically converts all "DS" declarations into equivalent "DC" declarations
using a value equal to zero. The previous two examples would therefore be
translated to the following:
In the expansion of the data word, its least significant byte is located at
the current program reference counter while the most significant byte is
located at the reference counter plus one. The data word can be a numeric
constant, an expression that evaluates to a 16-bit value, or a character
constant of one or two characters. The following examples illustrate various
forms of "DW" data declarations.
It would be unusual for an ORG to follow a COMMON. An ORG cannot follow a
named common. A COMMON will set the specified common relative program counter
to the beginning of the common segment (i.e. to zero relative).
The assembler defaults to CSEG if no other segment pseudo-OP is specified;
however, if MRAS is invoked with the -GC switch, it will default to ASEG.
Labels defined as "DEFL" will be carried as "DEFL" in the EQUate file
generation of the Cross-Reference utility. They will also be notated in the
cross-reference listing by a plus sign, "+", prefix to the label name.
A symbol can also be implicitly declared PUBLIC by appending two colons to
the "name" where the symbol is defined. Thus, the following two methods both
declare the symbol, TRUST, as PUBLIC:
An "EQU" can occur only once for any label. A multiple "EQU" with different
values will result in the MULTIPLY DEFINED SYMBOL error.
If you want to switch off the offsetting operation of LORG, add the statement:
LORG is usable only when generating CMD files directly from the assembler via
the -GC switch. LORG cannot be used when generating REL output.
A program can have more than one "ORG" statement. If multiple "ORGs" are
used, and one or more inadvertantly will cause the overwrite of a previously
assembled module of code, no warning message of any kind will be issued. It is
left up to the programmer, to protect against such events by use of
conditional tests (using conditional pseudo-OPs) and the "ERR" pseudo-OP.
An ORG can follow an ASEG, CSEG, DSEG, or COMMON //; but not a named common.
When ORG follows a relative segment specification, the program counter will be
set relative to the beginning of the segment, an amount equal to the operand
of the ORG. The operand of the ORG must evaluate to an absolute value.
The conditional construct of IF-ELSE-ENDIF may be used. It is coded as:
As mentioned earlier, the IF argument can take one of three forms. The
conditional structures of these are as follows:
If, for instance, you want to ensure that a program does not assemble code
past a particular address, then the ERR pseudo-op could be used in conjunction
with IFGT to force an assembly error as follows:
The "IFEXT name" pseudo-OP will evaluate TRUE if "name" has been declared
EXTRN. "IFNEXT name" will evaluate TRUE if "name" is not declared extern.
"IFABS name" will evaluate TRUE if "name" is defined in an absolute segment
whereas "IFREL name" will evaluate TRUE if "name" is defined in one of the
relative segment types (code, data, common).
The Type III constructs will find greater use when working with source
libraries of code. For instance, if a clause is a routine that is surrounded
with an IFREF-ENDIF conditional, the routine will only be assembled if prior
to the clause, the "name" has been referenced but not yet defined. If "name"
is the entry point symbol to the routine, then the routine will be assembled
if it is needed. Similarly, you may have a library routine that is always to
be placed in your program unless its "name" has already been defined in some
alternate routine. Surrounding it with the IFDEF-ENDIF conditional will
inhibit its assembly if your program has defined that "name".
The COM pseudo-OP will generate a comment block in the object file of the
format X'1F' followed by the string length, followed by the string itself. A
typical use would be to place a non-loading copyright statement in an
executable object code file. For example:
The OPTION pseudo-OP is only processed during the first pass; therefore, you
cannot use it to dynamically switch options ON and OFF during an assembly. It
is used to conveniently set options specific to a source stream to eliminate
the need for their entry on the assembler command line.
"SPACE n" performs line spacing whenever the "SPACE" pseudo-OP is used. When
assembled, "n" is the number of lines to space and is interpreted as modulo
256. The line containing the SPACE pseudo-op is not displayed. This pseudo-op
also will be ignored if it appears between *LIST OFF and *LIST ON.
A sub-title to a heading is permitted with the "SUBTTL" pseudo-OP. The
subtitle string length can be from zero (0) to 80 characters in length. A zero
length indicates that sub-titling is disengaged. The SUBTTL string does not
need to be enclosed in angle brackets; they are optional. SUBTTL also
automatically invokes a PAGE.
Lower case strings can be maintained by the use of single quotes which
surround the angle brackets. You may change the subtitle by using additional
SUBTTL pseudo-OPs throughout the text. Subtitles will appear on the first page
following the SUBTTL pseudo-op. If the SUBTTL text string is null (of zero
length), then subtitling will cease on the subsequent page. A line will also
be skipped between the subtitle and first printed text line on the page. Where
many *GETs are being used, you may want to establish a sub-title for each to
provide a visual indication on the listing.
The TITLE pseudo-OP automatically invokes a page heading and adds the title to
the headings of assembler listings. The title string is limited to 28
characters and only one TITLE is accepted. The angle brackets must be entered
but are not output in the listing - they serve only to delimit your title
string. The title line will include the MRAS version, the date and time
retrieved from the system, your title string, and a page number [page number
is limited to the range <1-255> and will wrap around to zero if more
than 255 pages are printed]. For this reason, if you use a title, it is
advisable to set DATE and TIME prior to executing the assembler. A line will
be skipped between the title and start of printed text (or subtitle if used).
Lower case titles will be maintained by surrounding the angle brackets with
single quotes as in:
"*GETs" can be nested to four (4) levels. That is, a statement can GET a file
which GETs a file which GETs a file file which GETs a file. This assembler
directive is extremely powerful. It can be used to provide the capability of
assembling large programs which are stored on disk in a series of source files
as one assembly stream.
Labels such as $?001 will have the "?" replaced with the current MOD string
value. Thus, a *MOD directive preceding each module will force $?001 labels in
each module to be distinctly named by having the question mark replaced with
the substitution string. The MOD string value cycles from A-Z, then from
AA-AZ, BA-BZ, ..., ZA-ZZ, then from AAA-AAZ, BAA-BAZ, ..., ZZZ.
This will allow for a simulation of "local" labels. Remember, the "?"
substitutions will only be made if *MOD was specified.
MRAS will search the PaDS library and locate a member name that matches up
with a symbol table entry. If that symbol is currently undefined, the member
will be accessed and read just as if it were the target of a *GET. MRAS will
verify that the member just accessed did in fact define the symbol invoking
its access. If a member is accessed and there exists no defined symbol in the
member that has the same name as the member name, MRAS will abort the assembly
and advise of a library error by displaying the message:
Where more than one routine is in a member, each should be surrounded by
IFREF/ENDIF and each should have an entry in the member directory (you must
use the MAP option of PaDS to provide multiple entries to a member). This will
benefit by not having needless routines appear in your object code output. For
example, the following depicts two routines stored as one member.
There are a few ways to deal with routines that are repeated in a program. You
could block copy it from the first appearance to wherever you needed the
routine. Or you could establish the routine as a macro. The first method could
take up more source storage than is desirable. Also, if you decide to change
the routine's algorithm, having many copies in a program can be cumbersome to
update.
The second method mentioned is the use of macros. Consider the following
commonplace sequence of code:
We invoke the statements defined in the macro by specifying the macro name AS
IF IT WERE AN OPCODE. Using the macro invocation method, we can save storage
space and introduce structured techniques to our coding. Notice that we have
used some fictitious names when the STOR macro was defined. These names are
called "dummy" parameters. They serve to provide a means to pass actual
parameters when the macro is invoked. Through the dummy parameters, the real
power of the macro is utilized. During the macro invocation, the model
statements are expanded with substitutions for the dummy parameters that are
provided in the macro call.
When a macro is defined, it is not assembled into your program. The macro
prototype is parsed and analyzed. The macro definition is then stored in a
compressed format within the macro storage area. Comments appearing with the
macro definition are not stored if the comment starts with a double semi-colon
in lieu of a single one. Comments with a single semi-colon are thus carried
through a macro expansion to the listing.
Macro definitions may be nested. The inner macro will not become defined until
the outer macro is expanded during an invocation. However, since macros cannot
be redefined, the outer macro should be invoked only once!
The MACRO pseudo-OP is used to define the prototype of a macro model. Its
syntax is:
Default strings can contain any character except the comma, ",". The comma is
used as a field delimiter. There is no limit to the length of a default string
other than the limiting factor of the statement length.
Macros must be defined prior to use but can be defined in a separate disk file
accessed via a "*GET filespec".
MACRO parameters are acceptable within a quoted string if prefixed by an
ampersand. i.e. TEST DB '&#NAME'. See the following example.
Macro definitions also may be nested. The inner macro will not be
defined until the outer macro is expanded. For instance:
If macro A "calls" another macro, say B, any dummy parameter in the macro call
of B that matches a dummy in macro A, will be considered part of macro A and
the parameter substitution will be invoked by the parameter passed when the
user calls macro A.
During the expansion, the "actual" parameters passed in the call statement are
substituted for the "dummy" parameters which appear in the macro model and
which are designated in the prototype of the macro. Note that the actual
parameter values are character strings and can be labels, expressions, or data
constants. An actual parameter can even be a quoted string data declaration if
its use is designed into the macro model.
The entire expanded macro model is listed during the listing pass (phase two).
Macro expansions in the listing will be so noted by the appendage of a plus
sign immediately following the line number displayed. You may find that you
don't really want to see these expansions since the macro definition contains
the entire illustration of the macro. An assembler switch, "-NM" is provided
to suppress listing of macro expansions. In the case of nested macro calls
(i.e. a macro is defined which calls another macro which was separately
defined), only the primary macro call will be listed if the "suppress" switch
is invoked.
The substitution of the actual character string parameters for the dummys
occurs during the macro expansion when the macro is called. Since a macro can
have more than one parameter, it is necessary to have a procedure that
specifies which actual parameter corresponds to each dummy parameter. There
are two methods supported in MRAS. Parameters can be passed to the macro
expansion when calling by either position or keyword.
If you wish to omit an actual parameter in a macro call, then you must supply
the comma to denote its place. For instance:
Note that the parameter list contains five parameters. Thus if you were to use
the "%%" operator which returns the number of parameters passed in a macro
call ("%%" is described later), it would return a value of five.
MRAS provides a facility for doing this by keeping a substitution string which
is changed each time a macro is expanded. The string replaces the question
mark character, "?", during a macro expansion whenever it appears outside of
single quotes in a macro model statement. Each time a macro is expanded, the
string will be changed. The string starts with the single letter "A", changes
to "B", ..., "Z", then increments to the two-letter strings, "AA", "AB", ...,
"ZZ", then to three letter strings, AAA-ZZZ each time a macro call is made. By
using the question mark as one of the characters in symbols of a macro model
statement, it will uniquely identify labels local to a macro. You may want to
standardize the way you create labels to ensure that uniqueness is maintained.
For example, you may use macro labels of the form, "$$?1", "$$?2", ... You can
repeat the use of "$$?1", "$$?2", ... in another macro since the substituted
string will be unique for each macro expansion.
The substitution string will be different from the *MOD directive substitution
but is similarly used. Macro expansion substitution of "?" takes precedence
over *MOD substitution. In the case of nested macros, each nest level will
have its own unique substitution.
By using the question mark string substitution specifier, the previous macro
would be defined like this:
FILL MACRO #CHAR,#NUM
LD B,#NUM
$$?1 LD (HL),#CHAR
INC HL
DJNZ $$?1
ENDM
These string conditional pseudo-OPs can only be useful in macros. That's
because the evaluation, to make sense, has to be dynamic.
These values can be tested arithmetically to produce a TRUE/FALSE result (as
was just demonstrated), or they can be used directly to represent logic
TRUE/FALSE conditions. Realizing that if a parameter was not passed in the
parameter list of the macro call, its length would be zero. A zero is also a
logical FALSE. MRAS will accept as TRUE, any non-zero value (in normal use of
TRUE/FALSE specifications, "-1" is recommended for TRUE to maintain proper
evaluation of the ".NOT." operation). Thus, the string lengths can be
minimally used to test if the parameter was not passed (%#parm=0=FALSE) or the
parameter was passed (%#parm<>0=TRUE).
Three different types of assembler errors can occur. The types relate to the
severity of the error. These types are:
Any attempt to load or *GET a file that has a line longer than 128 characters
will result in "Load file format error".
If you attempt to assemble a file that is not a valid source code file, the
message, "Bad parameter(s)" may be displayed.
At the conclusion of processing a complete command input line, you will be
prompted via '?' to enter another command line. A <BREAK> is an
immediate exit to DOS. Command line entry uses the KEYIN handler and is thus
usable from Job Control Language.
If any error is detected in an input, it will result in an appropriate error
message and any remaining input fragment(s) from that entry will be ignored.
File I/O errors may result in MLINK aborting.
The '-E' switch will also display this status prior to generation of any
specified output file.
The action of the -Q switch may be restored to the default mode of module
segment order by entering the -Q switch without a parameter [-Q].
If you specify the -V=filespec switch, all modules subsequently loaded will be
buffered through the virtual memory file specified. If you enter the switch
with only a drivespec as the parameter (as in -V=:d), the filename generated
will be MLINK/VMF:d. Note that the VM file is deleted during processing of the
-E switch.
If you are using virtual memory buffering and still get a "Symbol table
overflow" error, attempt to reclaim any high memory used by filters, drivers,
or resident programs so as to increase the size of the buffer are available to
the linker. Once you have exhausted that procedure, examine the memory usage
requirements of the linker and then attempt to "compact" some of the modules
making up your program.
DSEGs and COMMONs, Specify "-Z=Y". All space skipped over by DS/DEFS in CSEGs
will be set to zero in the output object file.
The action of the -Z switch doesn't take effect until the generation of output
but will pertain to all modules. To turn off the -Z switch and revert to
normal MLINK operation, specify "-Z=N". This switch defaults to -Z=N.
An output file is only generated when the -E switch is invoked if the -N
switch has been specified. The -E command will first check for any multiply
defined symbols and abort the operation if at least one symbol is defined at
more than one address. Any "Request library search" requests will be first
satisfied by searching the referenced libraries. If any symbols are left
undefined, they will be displayed and the request will be aborted. The linker
will recycle to request another command. Otherwise, next, the chain external
requests will be handled. Finally, the extern+offset requests will be handled.
If $MEMRY is defined, it will be loaded with the address of the first free
byte. The loaded modules are now ready for object code generation.
If you specified "-H=y", a 05 header record will be generated using the module
name of the first file loaded. After the header record, a record type 1F will
be generated if you specified the "-Y=<text>" switch.
Note: MLINK handles the module bit stream on a segment record basis which
incurs a great deal of overhead in the linker compared to a memory-fixed
linker such as L-80. The method was chosen for MLINK so as to minimize the
size of the resulting /CMD file. This is important for TRS-80 systems.
Each chain external requires 8 bytes of storage.
Each extern+offset requires 8 bytes of storage.
Each entry symbol requires 5 bytes of storage plus the length of the symbol.
Each request library search takes 3 bytes plus the name length.
Each -O switch takes 20 bytes.
When the -O switch is entered, MLINK will perform a fixup of the current chain
of modules loaded. The fixup process will:
MLINK provides support for up to 35 overlays. Each overlay is automatically
assigned a file specification which consists of the filename assigned by the
-N switch and an extension of /OVx: x = 1,2,...,9,A,B,...,Z. MLINK provides a
subroutine to automatically invoke a desired overlay. The protocol for its use
is as follows:
From "DOS Ready", the librarian is invoked simply by entering:
MLIB will accept either uppercase or lowercase for all keyboard input.
Whenever MLIB asks you to enter a file specification, you do not normally have
to enter an extension; it will default to either "/IRL" or "/REL", depending
on whether you request Indexed ReLocatable modules or RELocatable modules at
the "IRL or REL ?" prompt.
Certain options require you to enter either a file specification or a module
name. MLIB will fully buffer your keystrokes. Several special function keys
are available:
In interactive mode, with certain exceptions, MLIB will prompt you to set your
printer to the top of a page - do so and then depress any keystroke to
continue. If you are running MLIB under LDOS, you can use the system spooler,
or you can have printer output routed to a file. In either case, output will
begin with a form feed, and there will be no prompt for top-of-form.
In batch mode, the module map will always go to the printer, and will begin
with an automatic form feed and no prompt for top-of-form.
The detailed format option is available in both interactive and batch modes.
The attributes of each module are displayed as shown in the following
illustration:
The summary format option lists all modules, by name only, in the order they
exist in memory (from left to right, top to bottom, on the CRT screen).
Summary format is available only in interactive mode and would look like:
MLIB will request each command with the prompt "Enter option:". The valid
responses to this prompt are: Add, Clear, Extract, Insert, Load, Map, Purge,
Replace, Save, or Xit. Only the first letter of each command is significant;
the remaining letters are ignored and may be left out of the command line.
Command lines may also be commented. Each command line must be terminated with
a carriage return.
Prompts may be given to, "Enter filespec:" which expects a JCL line containing
a file specification; and "Enter module name:" which expects a JCL line
containing the name of a module which is currently in the symbol table.
The "Module map" command will default to a detailed map which will be printed.
The listing will start with a form feed.
Any command which writes out a disk file will automatically overwrite an
existing file; you will NOT be given the chance to abort this command.
The "Clear buffer" and "eXit program" commands will do just that, with no
opportunity to abort.
The occurrence of ANY error is fatal, and will terminate the batch processing
via the DOS ABORT error return.
Here is an example of a typical series of commands for a batch operation. The
comments may be included in the batch file.
The next three-line menu is optional. Its display mode is established when
SAID is invoked by the MENU setting during the SAIDINS installation. The META
command also permits you to toggle the display of this menu. It is recommended
that you keep the menu displayed until you get proficient at using SAID's
editing commands. The menu displays the command function activated when the
key identified by the second line is pressed simultaneously with the
<CLEAR> key. The first line designates shifted keys and the third line
designates unshifted keys.
The next line contains a great deal of information. The file specification of
the file currently being edited in the context buffer is identified by
"aaaaaaaaaaaaaa". The current length of the text is shown as "bbbbb" while the
total length of the editing buffer is shown as "ccccc". SAID keeps track of a
logical line number for the text. For line numbering purposes, a line is
considered to be all characters up to and including a carriage return. The
number of the line to which the cursor is positioned to is shown as "ddddd".
The video column number to which the cursor is positioned is shown as "ee".
This value will range from column 00 to column 79 (63 in the case of a 64
column screen). The character which the cursor is positioned over has its
value shown in hexadecimal as "ff". This value is useful for determining the
text character for undisplayable character values. SAID also keeps a ratio of
where the cursor is positioned relative to the end of the text. This is shown
as a percentage by the "ggg" value. It is accurate only when the text exceeds
99 characters.
The last field of the status line shows the availability of editing buffers as
"hhhhhhh". When SAID is invoked under those systems supporting banked
switching, SAID scans for the availability of up to seven editing buffers.
SAID will display a dash for each buffer that is available. These are selected
by you with the assignments 1, 2, 3, ..., 7. Anytime that you have entered
text into one of these buffers, its corresponding dash will be changed to a
plus sign.
The next line of status shows the current search string: "iiiiii..."; the
current replacement string: "jjjjjj..."; the search direction, "kkk":
"For=forward", "Rev=reverse"; and the macro repeat count: "lll".
The last line will be used to display prompting messages or error messages on
an as required basis.
XREF can also be used to generate an assembler source file of EQUates of all
symbols used in the program being assembled or a subset of all symbols used.
The LIMIT parameter is used to limit the EQUates to only those symbols having
at least one special character in the symbol name.
XREF uses, as input, the reference data file which is optionally generated by
the -XR switch during the LISTING pass of MRAS (phase 2). XREF cannot function
without this data file. You need not enter the file extension, /REF, as it
will be assumed if omitted.
The XREF command line parameters enclosed in parentheses are entirely
optional. The may be used as follows:
The listing will contain a heading on each page composed of the system DATE
and TIME, the TITLE pseudo-op text, and a page number. The heading needs a
minimum of 74 columns. Thus, you should not specify a LEN parameter of less
than 74. The reference columns will include:
Avoid writing modules with multiple entry points. Modules written in this way
can often lead to confusion and inefficient programming.
Library sizes are absolutely limited by the size of MLIB's memory buffer. In
practice, however, a smaller library size of about 10K bytes is most useful
for three reasons: (a) MLINK library searches will take less time; (b) the
library will fit into MLIB's buffer even if you have a lot of things in high
memory; (c) you will have some room for library growth.
Build special purpose libraries (e.g. communications, graphics, string
processing, disk I/O).
Use MRAS's CSEG (code segment), DSEG (data segment), and COMMON pseudo-OPs
only! DO NOT use ASEG (absolute segment), as this produces object code which
is not relocatable and thus not usable in a general purpose library.
Libraries of related routines must be constructed in a particular order. This
order is determined by each module's external references. If, for instance,
module A references module B, then module B MUST FOLLOW module A in the
library. Otherwise, a backward reference will occur, and MLINK may force you
to search the library TWICE in order to satisfy the reference. If the library
is constructed as an IRL, MLINK will perform multiple searches automatically;
however, minimum processing time will occur in searching an IRL when no
external reference is to be resolved by a module which is stored before the
module having the extern.
You may encounter a problem if you try to use MLIB on libraries not created
with MLIB. This is because the end-of-file marker in these files may not match
the EOF in the directory. There is a simple solution: create a text file using
SAID which contains a single character of value 9EH; append this file to the
problem file; load the /REL file into MLIB, and immediately resave it. This
caveat also applies to any /REL files constructed under CP/M which have been
transferred over to your system.
Let's look at an example of absolute assembly. The following program has been
assembled at an ORIGIN of 0100H. Notice especially the values assigned to the
memory addresses @DATE, @EXIT, @DSPLY, START, and BUFFER:
The same program, as assembled using relocation looks like this:
This characteristic of relocatable object files, that they can be LINKED at
any origin, is extended by a further capability: relocatable object files may
be linked TOGETHER to form a complete program from many smaller pieces. This
allows you to write a very large program in lesser chunks which are easier to
edit and to understand. In addition, you can develop libraries of standard and
useful subroutines, each thoroughly tested and debugged, which any main
program may call upon when necessary. The Microsoft FORTRAN library
(FORLIB/REL), for example, thus contains many subroutines which can be used by
any FORTRAN or Z80 assembler program.
The mechanism of program and subroutine linkage that is often used is
implemented by the ENTRY and EXTERNAL attributes. A label which is declared
ENTRY (or GLOBAL or PUBLIC) in one module can be accessed by another module in
the following way:
MLINK has other capabilities, such as the use of COMMON blocks, which are
explained in sections on MRAS and MLINK. MRAS can also generate absolute code,
if you use the ASEG command.
Finally, we get to the actual format of a Microsoft relocatable object file. A
/REL file is composed of a bit (not byte) stream. Each /REL file may contain a
table of ENTRY points and EXTERNAL references. Each ENTRY point is identified
by its name (1 to 7 ASCII characters) and its relative location within one of
the module's code, data, or common segments. Each EXTERNAL reference is
identified by its name, and also by a chain (or linked list) of pointers, each
of which locates the relative address within the module where the external was
used. The last pointer in the chain is zero. The /REL file also contains
internal relocation data necessary for resolution of label references within
the module. All external and internal relocatable references are changed to
absolute values at link time, when the program's segment origins have been
established. The remainder of the information in the /REL file consists of
absolute code and data bytes which do not need relocation, and numerous other
fields which describe common blocks, the module name, the module segment
lengths, and the /REL file end (or EOF byte). A library file would contain
many such modules, each separated by program end indicators, and terminated by
an EOF byte.
Let's take one last look at our example, modified slightly, to see what the
relocatable object file assembled from this source code would look like:
The following is a tabular picture of the decoded /REL file. Each column
represents:
1) IF the next bit is a zero, THEN the following eight bits are loaded
according to the value of the location counter currently in effect, THEN
recycle to 1).
ELSE IF the next bit is a one, THEN the next two bits represent a code which
is interpreted as follows:
Important Note
Certain documentation pertaining to this package may be available after the
user manual has gone to press. Consult the file entitled README/TXT for
details on additional support material and errata. General Information
The MISOSYS Relocating Macro Assembler (MRAS) is a disk assembler which
generates a relocatable (REL) module from one or more source files. The REL
module generated by MRAS is a bit-stream compatible with Microsoft (TM) M-80
generated files. Multiple REL modules are then linked via the MISOSYS linker
(MLINK) to produce an executable object code file (CMD). The assembler is also
capable of directly generating a CMD file when the source file(s) contain no
references to relocatable segments. Source files may be created and edited
with the full screen text editor (SAID) provided. Libraries of relocatable
modules are organized with the librarian (MLIB).
FIXUP/CMD - a utility to convert from/to line-numbered source files
MLIB/CMD - a relocatable module librarian
MLINK/CMD - a relocatable module linker
MRAS/CMD - a macro assembler generating relocatable modules
OVERLAY/REL - a module which supports overlay handling
README/TXT - a LISTable text file containing errata
SAID/CMD - a full-screen text editor for source code preparation
SAIDINS/CMD - SAID installation program
XREF/CMD - a symbol cross-reference listing generator
All source text to MRAS must have a Control-Z (1AH) as the last character of
the text. This byte must immediately follow a CARRIAGE RETURN (0DH). If you
are using an editor other than SAID to prepare your source text, and that
editor does not terminate the text file with a CONTROL-Z, you may have
difficulty in using the file with the assembler. If such is the case, load the
file into SAID using the ASM parameter and resave it (after ensuring that the
last character in the file is a carriage return).
FIXUP filespec {(*/strip/header/number}
where the parameter "strip" is used to eliminate headers and line numbers,
"number" is used to add line numbers, and header is used to add both a header
and line numbers. The '*' is used to rewrite the file left in the FIXUP
buffer. FIXUP defaults to "strip"; reads its input from and writes its output
to the file identified as "filespec". Distribution Disks
The TRSDOS 6.x MRAS Development System is distributed on a 40-track double
density data diskette. Model I TRSDOS 2.3 Patch
Model I TRSDOS users will find difficulty in reading the distribution disk due
to the data address mark used for the directory. Therefore, before making a
BACKUP or copying MRAS files from the diskette, you will need to change one
byte of the TRSDOS 2.3 disk driver using either of the following two methods.
This change should not affect the operation of your TRSDOS.
10 OPEN"R",1,"SYS0/SYS.WKIA:0"
20 FIELD 1,171 AS R1$, 1 AS RS$, 84 AS R2$
30 GET 1,3: LSET RS$="<": PUT 1,3: CLOSE: END
Method (2) uses a POKE from BASIC to change the value directly in memory. This
procedure is as follows:
1. Enter BASIC (files = 0, protect no memory)
2. Type POKE &H46B0,60 followed by <ENTER> .
3. Type CMD"S followed by <ENTER> .
Now, after using either method noted above, COPY the MRAS files from the
master diskette to your TRSDOS system diskette. Invoking MRAS
MRAS is a macro assembler used to assemble a source disk file(s) into a
relocatable object code module. MRAS provides a command line rich in features.
The syntax:
________________________________________________________________
| |
| MRAS source/ASM {+L=listing/PRN +O=object/CMD +X=reference/REF |
| +S=symbol/SYM +I=include/ASM } {assembler switches} |
| {(p1=value1,p2=value2,p3=value3,p4=value4,LINES=n)} |
| |
| +L=listing/PRN - send listing to spec in lieu of *DO. |
| +L=:d Use -LP for printer (or +L=*PR if DOS |
| supported). Will inhibit -NL and -LP. |
| |
| +O=object/REL - send object to spec in lieu of "source/REL".|
| +O=:d Will inhibit -NO. |
| |
| +X=reference/REF - send cross reference data to spec in lieu |
| +X=:d of "source/REF" if -XR switch invoked. |
| Will invoke -XR. |
| |
| +S=symbol/SYM - send symbol table to spec in lieu of *DO or |
| +S=:d *PR depending on setting of -WS and -LP |
| switches. Will invoke -WS. |
| |
| +I=include/ASM - use spec for "*INCLUDE" assembler directive |
| which is similar to "*GET". |
| |
| Switches: -CI -FE -GC -LP -MF -NC -NE -NH |
| -NL -NM -NO -SL -WE -WS -XR (see text) |
| |
| Parms: |
| Pn - Set internal symbols (see text) |
| Lines=n - set printed lines per page to n (abbrev=L). |
| |
| Note: Default file extensions are shown capitalized in the |
| file option filespecs. |
|________________________________________________________________|
File options
File options are denoted with a plus sign prefix and are used to redirect one
or more output streams of the assembler. They can accept a syntax of
"+s=filename:d" or "+s=:d". The "s" refers to any of the file switches: O, I,
L, S, X. The latter will re-use the source filename for the file being
switched and the extension appropriate for the switch. File switches must
precede the assembler switches. Assembler switches
These switches control various aspects of the assembler. They are always
prefixed with a minus sign.
Switch -CI
The "-CI" switch is used to generate a "core-image" object code file.
Executable command files in the DOS are constructed with address information
that the system loader uses when loading and executing your command file.
Also, a header record is usually found in a load module object code file. When
the "-CI" switch is specified, a number of changes take place in MRAS. First,
the object code file default extension is changed to "/CIM". Next, the header
record and the transfer address record are suppressed. Any COM pseudo-OP
statement is, likewise, suppressed. A core-image file needs to contain
contiguous address sequential code. Since MRAS reserves only storage locations
when assembling the DS/DEFS pseudo-OPs, DS instructions will automatically be
converted to their corresponding "DC" statements with a zero value for
operand2. The "-GC" switch will also be turned on.
Switch -FE
The normal operation of MRAS will suppress the output of linkage data for
symbols declared EXTRN but never referenced within the source code stream.
This switch forces chain external linkage data to be generated for external
symbols declared via EXTRN where no reference is made in the module. This can
be used to force a loading of the extrn'd module from a library even though no
other reference is made in the module with the EXTRN. Its use is generally
associated with the inclusion of desired library modules into the ROOT segment
of an overlayed program. If -FE is not specified, any symbol listed in the
argument of the EXTRN statement which has no other reference in the module
will not generate a "chain external" and will not be searched for in a library
search.
Switch -GC
This switch tells the assembler to directly output a CMD file. The normal
object file output is a relocatable module (/REL). Do not specify this switch
if your source contains any CSEGs, DSEGs, or COMMONs. The -GC switch is
automatically turned on by switch -CI. The assembler will default to ASEG if
this switch is specified.
Switch -LP
The -LP switch is used to send the assembler listing, error messages occurring
during the assembly of your source code, and the symbol table listing (if
specified by means of the "-WS" switch) to a line printer. MRAS assembler
listings print 56 lines per page and send a form feed at the conclusion of the
56 lines. If you are generating a listing output and a
properly paged display is desired, it is suggested that you set your paper to
begin printing at the sixth line from the top of the page (which assumes
paging parameters set at 56 print lines and 66 lines page length -- the
default). This will provide five blank lines for a top margin, and five blank
lines for a bottom margin. Switch -MF
The assembler normally searches the OP code table prior to the macro table. If
you want to redefine the code generation of Z-80 OP code mnemonics, you can
specify the -MF switch. It causes the assembler to search the macro table
before the OP code table. Switch -NC
Conditional assembly (see the section on ASSEMBLER PSEUDO-OPS) can greatly
ease the maintenance of programs designed to work with multiple configurations
of hardware. However, it is unnecessary to "see" the source statements within
conditional clauses that are logically "false". This -NC switch is provided to
have no "false" conditionals appear in your listings. If a conditional is
suppressed, neither the "IF" statement nor the "ENDIF" statement of the
"false" clause will be listed.
Switch -NE
Various data declaration pseudo-OPs create a structured format for the listing
of code generated after the first byte of the statement. These are the
DB/DEFB, DM/DEFM, DW/DEFW, and the DC pseudo-OP statements. If you want to
inhibit the expansion from the listing only (the code will still be expanded
for assembly of object code), then specify the "no expansion", -NE, switch.
Switch -NH
Object code files usually start off with a header record of X'05 06 xx xx xx
xx xx xx'. The x's would be replaced with the first six characters of the
object code filename (buffered with spaces). MRAS automatically generates this
record when writing an object code CMD file. The DOS loader has no problem
with this record. If you would like your object code files to contain this
record, then do absolutely nothing. If you do not want to have this header
record generated, then specify the "no header", -NH, switch.
Switch -NL
The second phase of the assembly process generates the assembler listing. If
you do not want to see a listing, then you may enter the "no listing", -NL,
switch. This will completely suppress phase two and shift the assembler to
phase three. If you are interested in listing statements containing errors,
then you must not suppress the second phase. Note that the lines containing
only assembly errors can be listed by specifying the "*LIST OFF" assembler
directive. See the section on "ASSEMBLER DIRECTIVES" for further details.
The cross-reference data file is written during phase two. In order to
guarantee that the second phase is available, a cross-reference specification
will automatically override any entry of the -NL switch.
Switch -NM
The macro model code is repeated whenever you invoke the macro. Once you
become familiar with what the macro does, you really don't need to see its
expansion in your listings every time the macro is invoked. Switch -NM has
been provided to inhibit the listing of such expansions. If you specify no
macro expansions, only the statements invoking the macros will be listed --
the listing of the expansions will be inhibited. In the case of a nested macro
invocation, only the highest level macro call will be listed.
Switch -NO
MRAS will generate an object code output file unless you tell it to suppress
this generation via the -NO switch.
Switch -SL
If you specify -SL, then any label starting with a dollar sign, "$", will be
suppressed from the symbol table listing and from any cross-reference data
file. Therefore, by using a "$" as the first character of local labels and
specifying -SL will result in keeping your symbol table listings uncluttered
with local labels.
Switch -WE
In a long assembly, you may want the assembler to pause the listing if it
detects an assembly error (you're bound to get some of them). The "wait on
error" switch, -WE, is available for that purpose. If specified, each time the
assembler comes to an error during phase two, it will pause the listing. Any
character entered from the keyboard will continue the assembly and listing. If
you choose to enter the character "C" or "c", then the phase two process will
continue without further interruption - even though additional errors may be
detected. The listing may also be paused at any time by depressing the
<SHIFT-@> key, momentarily.
Switch -WS
A complete symbol table cross-reference listing of a single assembly stream
is available via the -XR switch and subsequent processing by the XREF/CMD
program. An abbreviated printout that contains only a sorted listing of
symbols and their value is available at assembly time by invoking the -WS
switch. The symbol table listing would normally be displayed on the video
display. If the -LP switch was specified, the listing would be directed to the
Line Printer. The symbol table can also be invoked via the "+S=filespec" file
option.
Switch -XR
This is the switch option to use if you want to generate a complete symbolic
cross reference listing of the assembly stream. Switch -XR will invoke the
generation of a reference data file used by the XREF/CMD utility (see the
chapter on CROSS REFERENCE UTILITY). The reference data file is generated
during the listing pass (phase two). If the XREF filespec is entered via
"+X=filespec", this switch is assumed to have been entered. If the XREF
filespec is not entered via "+X=", the filespec of the reference file will be
generated from the source filename.
Parameters: Pn=val
This parameter provides the power of entering symbol table equates directly
from the MRAS command line. "Pn" is actually four parameters as "n" can range
from <1-4>. Thus, you specify the parameter as either P1, P2, P3, or
P4. These parameters are entered in MRAS as absolute DEFL values added to the
symbol table. By passing parameter values with these on the MRAS command line,
you can alter four symbol table entries. Thus, you can use these to control
EQUate options, pass values to symbols, etc. The format usable is dependent on
that supported by your DOS and may include:
_____________________________________________________________
| |
| Pn sets @@n to TRUE. |
| |
| Pn=ddd sets @@n to decimal value ddd. |
| |
| Pn=X'hhhh' sets @@n to hexadecimal value hhhh. |
|_____________________________________________________________|
The actual labels added to the symbol table as DEFLs are "@@n", where "n" is
the same as the "n" of "Pn". This is depicted as follows:
_____________________________________________________________
| |
| P1 == @@1 P2 == @@2 P3 == @@3 P4 == @@4 |
|_____________________________________________________________|
The four symbols initially have a value of zero (logical FALSE). You can use
these to externally set flags for use in conditional assembly. For example,
say you have a program that uses two conditional symbols, MOD1 and MOD3. If
your program has the statements:
MOD1 EQU @@1
MOD3 EQU @@3
then an MRAS command line including (P1) will set "@@1" to
TRUE, "@@3" was defaulted to FALSE, and thus "MOD1" would be TRUE and "MOD3"
would be FALSE since the two conditional symbols you are using are equated to
the "@@n" parameters.
Assembler listing
During the first pass, the name of each file included or searched will be
displayed as an informative message. During the listing pass, MRAS keeps track
of each statement's logical line number within its source file and the logical
line number of the assembly output stream. Stream line numbers are output in a
sequential order incremented by one for each line of logical output. Lines
suppressed from display use up one line number for each line omitted [i.e.
from *LIST OFF to *LIST ON; -NC statements; -NM statements]. Lines containing
errors will be prefixed with the name of the file containing the line, the
line number within the file, and the error message. The statement itself will
display the stream line number.
blank - absolute
' - code relative
" - data relative
! - common relative
C - named common
* - extern symbol
At the conclusion of the listing pass, the free space remaining in the buffer
pool will be displayed as, "ddddd Free space". This can be used as an
indicator of how dangerously huge your program is getting.
Error totals
At the conclusion of pass three, the total number of errors will be listed. An
"Unclosed conditional" error is also included in the ERROR TOTALS count. This
error total will be displayed after the conclusion of phase two if object code
is not generated. If you place a "*LIST OFF" pseudo-OP at the beginning of
your code, lines containing errors will be listed.
Syntax
The basic format of an assembly language statement consists of up to four
fields of information. These fields, in order, are:
_____________________________________________________________
| |
| {LABEL} {OPCODE} {OPERAND{S}} {;COMMENT} |
| |
| LABEL is a symbolic name assigned the address value |
| of the first byte of the object instruction. |
| |
| OPCODE is the mnemonic of a specific Z-80 assembler |
| instruction or pseudo-OPeration code. |
| |
| OPERANDS are arguments of the OPCODE. |
| |
| ;COMMENT is an informative notation that is ignored by |
| the assembler but aids in documenting the |
| source code. |
| |
| Note: Fields are separated by a tab or spaces. |
|_____________________________________________________________|
As can be noted from the format box, none of the fields are required; however,
each line should contain at least one field. If you want the comment field to
occupy the entire line, start the line with a semi-colon in the first
character position of the line - then, no other field is needed. A symbolic
label can exist by itself on a line. There are some Z-80 operation codes that
have no arguments; thus, an OPCODE could exist by itself on a line (in field
2). You will never have an argument by itself as an argument relates to an
OPCODE. Symbolic names
A label is a symbolic name of a line of code. Labels are always optional. A
label is a string of characters of any length; however, only the first 15
characters will be significant. A symbol is defined as:
name{{:}:} Defines "name"
A terminating single colon is optional. A double colon defines "name" as
PUBLIC. If "name" is used as a reference suffixed with "##", then "name" is
declared extern. Labels designated as PUBLIC or EXTRN which exceed seven
characters in length will be automatically truncated to seven during the
generation of the /REL file without warning. If two or more labels with
identical first seven characters are so truncated, the linker will flag a
multiple definition error. The first character must be a letter (A-Z) or one
of the special characters: the underline, "_"; the dollar sign, "$"; or the at
sign, "@". It is recommended that you reserve use of "$" as the first
character of "local" labels since they can be suppressed from a symbol table
output via the "-SL" assemble switch
ALLALONE
ALLALONE EQU $
Certain labels are reserved by the assembler for use in referring to
registers. Others are reserved for branching conditions (condition codes) and
may not be used for labels. (these conditions apply to status flags). The
following labels are reserved and may not be used for other purposes:
_____________________________________________________________
| Reserved Labels |
| |
| A, B, C, D, E, H, L, I, R, |
| IX, IY, SP, AF, BC, DE, HL, ON |
| C, NC, Z, NZ, M, P, PE, PO, OFF |
|_____________________________________________________________|
Examples of labels:
ENTRY @OPEN BUFFER$ BYTE_POINTER WHAT?
SELECT_CODE $$CORE @ CARRIAGE_RETURN @EXIT
A special symbol is "$MEMRY". If this symbol name is declared PUBLIC, the
linker will store the address of the first available memory location which
follows your program into the word defined as "$MEMRY". Thus, if you choose to
use this capability, $MEMRY must be defined via a DW statement. or equivalent.
Opcodes
The OPCODES for the MRAS assembler correspond to those in the "Z-80-Assembly
Language Programming Manual", 3.0 D.S., REL 2.1, FEB 1977.
Operands
Operands are always one or two values separated by commas. Some instructions
may have no operands at all.
_____________________________________________________________
| |
| Data Type Radix Char Digits Examples |
| ----------- --------- -------- -------------------- |
| hexadecimal H <0-9,A-F> 1AH, 0ABH, 0FFH |
| |
| decimal D <0-9> 107D, 107, 15384 |
| |
| octal O or Q <0-7> 166Q, 166O |
| |
| binary B <0-1> 01101110B |
| |
| Note: Decimal is assumed if the radix character is omitted |
| unless *RADIX is used to change the default radix. |
|_____________________________________________________________|
A constant not followed by one of the radix characters is assumed to be
decimal. This assumption can be changed via the *RADIX assembler directive. A
constant must begin with a decimal digit. Thus "FFH" is not permitted, while
"0FFH" is valid. Comments
All comments must begin with a semicolon ";". If a source statement line
starts with a semicolon in the first character position of the line, the
entire line is a comment.
Expressions
A value of an operand may be an expression consisting of multiple terms
(labels and data constants) connected with mathematical operators. These
expressions are evaluated in strictly LEFT to RIGHT order. No parentheses are
allowed. MRAS does not support operator precedence. Most operators are binary,
which means that they require two arguments. Both "+" and "-" have unary uses
also. The following operators are supported:
_____________________________________________________________
| |
| Operator Function Example |
| |
| + Addition value1 + value2 |
| - Subtraction value1 - value2 |
| * Multiplication value1 * value2 |
| / Division value1 / value2 |
| .MOD. Modulo Division value1 .MOD. value2 |
| < Shift Left or Right value1 < -value2 |
| .AND. or & Logical Bitwise AND value1 .AND. value2 |
| .OR. or ! Logical Bitwise OR value1 .OR. value2 |
| .XOR. Logical Exclusive OR value1 .XOR. value2 |
| .NOT. Logical 1's Complement FALSE EQU .NOT. TRUE |
| .NE. Logical Binary Not Equal value1 .NE. value2 |
| .EQ. Logical Binary Equal value1 .EQ. value2 |
| .GE. greater than or equal to value1.GE.value2 |
| .GT. greater than value1.GT.value2 |
| .LE. less than or equal to value1.LE.value2 |
| .LT. less than value1.LT.value2 |
| .SHL. shift value1 left value1.SHL.value2 |
| .SHR. shift value1 right value1.SHR.value2 |
| .HIGH. obtain high order byte .HIGH.value |
| .LOW. obtain low order byte .LOW.value |
| % Length of MACRO %#LABEL or %% |
| %& MACRO label concatenation #NAME%&L |
|_____________________________________________________________|
Addition (+)
The addition operator will add two constants and/or symbolic values. When used
as a unary operator, it simply echoes the value.
001E CON30 EQU 30
0010 CON16 EQU +10H
0003 CON3 EQU 3
002E A2 EQU CON30+CON16
Subtraction (-)
The minus operator will subtract two constants and/or symbolic values. Unary
minus produces a 2's complement.
000E A2 EQU CON30-CON16
FFF2 A4 EQU -A2
Multiplication (*)
The multiplication operator will perform an integer multiplication of a 16-bit
multiplicand by a 16-bit multiplier. Overflow of the resulting 16-bit value is
not flagged as an error.
01E0 A5 EQU CON30*CON16
BF20 A6 EQU 60000*3 ;this overflows
Division (/)
The division operator will perform an integer division of a 16-bit dividend by
a 16-bit divisor.
0002 A7 EQU 5/2
1B4D A8 EQU 48928/7
Modulo (.MOD.)
The modulo operator calculates the remainder of the above integer division.
0001 A9 EQU 5.MOD.2
0005 A10 EQU 48928.MOD.7
Shift (<)
This operator can be used to shift a value left or right. The form is:
____________________________________________________________
| |
| VALUE < {-}AMOUNT |
|____________________________________________________________|
If AMOUNT is positive, VALUE is shifted left. If AMOUNT is negative, VALUE is
shifted right. The magnitude of the shift is determined from the numeric value
of AMOUNT.
0057 HIORD EQU 5739H<-8
C000 A1 EQU 3C00H<4
03C0 A2 EQU 3C00H<-4
BBFF A3 EQU 3CBBH<8+255
03C0 A3 EQU 15+3C00H<-4
Logical AND (.AND. or &)
The logical AND operator bitwise ANDS two constants and/or symbolic values.
Each bit position of the 16-bit resultant value is a "1" only if both
arguments have a "1" in the corresponding position, or a "0" if either
argument has a "0".
3C00 A1 EQU 3C00H&0FFH
0000 A2 EQU 0&15
0000 A3 EQU 0AAAAH.AND.5555H
Logical OR (.OR. or !)
The logical OR operator bitwise "ORS" two constants and/or symbolic values.
Each bit position of the 16-bit resultant value is a "1" if either argument
has a "1" in the corresponding position, or a "0" if neither argument has a
"1".
3CFF A1 EQU 3C00H!0FFH
000F A2 EQU 0.OR.15
FFFF A3 EQU 0AAAAH.OR.5555H
Logical XOR (.XOR.)
The logical XOR operator performs a bitwise exclusive OR on two constants
and/or symbolic values. Each bit position of the 16-bit resultant value is a
"1" only if both arguments have reversed bits in the corresponding position
(i.e. one must have a "1" while the other must have a "0"). The XOR operation
is considered a modulo two addition.
3CF8 A1 EQU 3C07H.XOR.0FFH
0007 A2 EQU 8.XOR.15
FFFF A3 EQU 0AAAAH.XOR.5555H
Logical NOT (.NOT.)
This is a unary operator. It performs a one's complement on the term it
precedes. Observe the following examples:
FFFE T1 EQU .NOT.1
FFFF T2 EQU .NOT.0
0000 T3 EQU .NOT.-1
Logical NOT-EQUAL (.NE.)
This operator is a binary operator that compares two adjacent terms. The
resultant value is TRUE if the terms are not equal. A FALSE result is returned
if the two terms are equal. Observe the following examples:
0000 T1 EQU 1000.NE.1000
FFFF T2 EQU 1000.NE.10
FFFF T3 EQU 1.NE.-1
0000 T4 EQU .NOT.0.NE.-1
Logical EQUAL (.EQ.)
This operator is a binary operator that compares two adjacent terms. The
resultant value is TRUE if the terms are equal. A FALSE result is returned if
the two terms are not equal. Observe the following examples:
FFFF T1 EQU 1000.EQ.1000
0000 T2 EQU 1000.EQ.10
0000 T3 EQU 1.EQ.-1
FFFF T4 EQU .NOT.0.EQ.-1
Logical GREATER-THAN-OR-EQUAL-TO (.GE.)
This is a binary operator that compares two adjacent terms. The resultant
value is TRUE if the left term is equal to or larger then the right term.
0000 T1 EQU 1.GE.2
FFFF T2 EQU 2.GE.2
Logical GREATER-THAN (.GT.)
This is a binary operator that compares two adjacent terms. The resultant
value is TRUE if the left term is larger than the right term.
0000 T1 EQU 1.GT.2
0000 T2 EQU 2.GT.2
Logical LESS-THAN-OR-EQUAL-TO (.LE.)
This is a binary operator that compares two adjacent terms. The resultant
value is TRUE if the left term is smaller than or equal to the right term.
FFFF T1 EQU 1.LE.2
FFFF T2 EQU 2.LE.2
Logical LESS-THAN (.LT.)
This is a binary operator that compares two adjacent terms. The resultant
value is TRUE if the left term is smaller than the right term.
FFFF T1 EQU 1.LT.2
0000 T2 EQU 2.LT.2
Logical SHIFT LEFT (.SHL.)
This is a binary operator that shifts the left term a number of bits left
according to the right term. It is the same as "value1<value2".
2340 T1 EQU 1234H.SHL.4
Logical SHIFT RIGHT (.SHR.)
This is a binary operator that shifts the left term a number of bits right
according to the right term. It is the same as "value1<-value2".
0123 T1 EQU 1234H.SHR.4
Obtain HIGH-ORDER byte (.HIGH.)
This is a unary operator that provides a low-order result which is equal to
the high order value. It is the same as "value.SHR.8".
0012 T1 EQU .HIGH.1234H
Obtain LOW-ORDER byte (.LOW.)
This is a unary operator that provides a low-order result which is equal to
the low order value. It is the same as "value.AND.0FFH".
0034 T1 EQU .LOW.1234H
Macro Length Operator (%)
The length operator is applicable only with MACRO usage. Therefore, its use
will be discussed in the section on MACRO PROCESSING.
Evaluation of expressions - limitations of mode/class
Symbols have both a mode and a class. The modes are absolute, code relative,
data relative, and common relative (which is common specific, i.e. coupled to
common relative is the specific common which the symbol is a part of). The
class is either extern or not extern. The following rules apply to all
expressions:
A. Addition:
1. One term must be absolute.
2. The resulting mode is: absolute + <mode> = <mode>
3. Either term may be extern but not both.
4. If one term is of class extern, the other must be absolute.
B. Subtraction:
1. <mode> - absolute = <mode>
2. <mode> - <mode> = absolute; both modes must be the same.
3. <extern> - absolute = extern; the result is extern
4. The second term cannot be of class extern.
C. All other binary operators require absolute terms. All unary
operators except unary minus require an absolute term. Unary
minus follows the rules of subtraction with the left term assumed
to be absolute.
Additionally, all expressions which resolve to a byte value (in contrast to
16-bit word value) must resolve to absolute mode, class not-extern. Pseudo-OPs
There are many pseudo-OPs which MRAS will recognize. These assembler
operations, although written much like processor instructions, interface to
the assembler instead of the Z-80 processor. They direct the assembler to
perform specific tasks during the assembly process but have no meaning to the
Z-80 processor. Some of these pseudo-OPs generate data values used by your
program and are called "data declaration" pseudo-OPs. Others control paging
operations and may be best termed, "listing" pseudo-OPs. A broad range of
operations to invoke the assembly of code clauses based on conditional
evaluations are supported through many "conditional" pseudo-OPs. These
assembler pseudo-OPs are:
________________________________________________________________
| Constant Declarations |
| |
| DATE Assembles system date as 8-character string, MM/DD/YY. |
| |
| DB Specifies a data byte or string of bytes. Also |
| equivalent to DEFB, DEFM, and DM. |
| |
| DC Specifies a multiple of byte constants. |
| |
| DS Reserves a region of storage for program use. |
| Equivalent to DEFS. |
| |
| DSYM Assembles "label" as an n-character string. (Similar |
| to the construct, DB '&#label', in a macro. |
| |
| DW Specifies a word (16-bit data value) or a sequence of |
| words. Also equivalent to DEFW. |
| |
| DX Assembles "expression" as a 4-hexadecimal digit string.|
| |
| TIME Assembles system time as 8-character string, HH:MM:SS. |
|________________________________________________________________|
________________________________________________________________
| Origins and Values |
| |
| ASEG Sets the program counter to the absolute segment |
| |
| COMMON Sets the program counter to a common relative segment. |
| |
| CSEG Sets the program counter to the code relative segment. |
| This is the default mode of the assembler. |
| |
| DEFL Establishes a value for a label which can be altered |
| during the assembly. |
| |
| DSEG Sets the program counter to the data relative segment. |
| |
| END Signifies the end of a *GET, *INCLUDE, or *SEARCH |
| member. Supplies the execution transfer address. |
| |
| ENTRY Synonomous with GLOBAL. |
| |
| EQU Estalishes a constant value for a label. |
| |
| EXT Synonomous with EXTRN. |
| |
| EXTRN Specifies the symbols in the name list as external. |
| |
| GLOBAL Specifies the symbols in the name list as entries. |
| |
| LORG Establishes a load origin for executable object code |
| files. LORG is unusable for /REL output. |
| |
| NAME Specifies the module's name for the /REL file. This |
| defaults to the object code filename. |
| |
| ORG Establishes an origin for executable object code files |
| or relative code segments. |
| |
| PUBLIC Synonomous with GLOBAL. |
| |
| Note: An ORG can follow ASEG, CSEG, DSEG, or COMMON //; but |
| not a named common. A maximum of seven named commons |
| are permitted in one module. The "name" of a common |
| cannot be the same as any symbol. |
|________________________________________________________________|
________________________________________________________________
| Conditionals |
| |
| ELSE Alternate clause to be assembled if the prior clause |
| has evaluated FALSE. |
| |
| ENDIF Signifies the end of a conditional block. |
| |
| IF Conditional evaluation of expression. |
| |
| IF1 Logically TRUE if the assembler is on the first pass. |
| |
| IF2 Logically TRUE if the assembler is on the second pass. |
| |
| IF3 Logically TRUE if the assembler is on the third pass. |
| |
| IFABS Logically TRUE if "name" is absolute. |
| |
| IFDEF Logically TRUE if "name" has been defined prior to |
| this statement or if "name" is extern, else FALSE. |
| |
| IFEQ Logically TRUE if expression1 = expression2. |
| |
| IFEQ$ Logically TRUE if string1 = string2. |
| |
| IFEXT Logically TRUE if "name" is extern. |
| |
| IFLT Logically TRUE if expression1 < expression2. |
| |
| IFLT$ Logically TRUE if string1 < string2. |
| |
| IFGT Logically TRUE if expression1 > expression2. |
| |
| IFGT$ Logically TRUE if string1 > string2. |
| |
| IFNDEF Logically TRUE if "name" has not been defined prior to |
| the statement or if "name" is not extern, else FALSE. |
| |
| IFNEXT Logically TRUE if "name" is not extern. |
| |
| IFNE Logically TRUE if expression1 <> expression2. |
| |
| IFNE$ Logically TRUE if string1 <> string2. |
| |
| IFREF Logically TRUE if "label" has been referenced but not |
| defined prior to the statement, else FALSE. |
| |
| IFREL Logically TRUE if "name" is relative. |
| |
| Note: "IFxx$" denotes alternate macro string comparison. |
|________________________________________________________________|
________________________________________________________________
| Miscellaneous |
| |
| COM Generates a CMD object code file comment record. |
| |
| ENDM Designates the end of a MACRO model. [**] |
| |
| ERR Forces an assembly error. |
| |
| EXITM Can be used to prematurely exit from a MACRO expansion.|
| This is normally used within a conditional. [**] |
| |
| IRP The statements within IRP-ENDM are repeated for as |
| many items are in the argument list with "dummy" being |
| replaced by each argument in turn. [**] |
| |
| IRPC The statements within IRPC-ENDM are repeated for each |
| character in the character-list while the "identifier" |
| is replaced, in turn, from the identifier list. [**] |
| |
| MACRO Designates the prototype of a MACRO model. [**] |
| |
| OPTION This permits the altering of any of the permissable |
| assembler switches from within the source code during |
| the first pass of the assembler. |
| |
| PAGE Outputs a form feed during a listing. |
| |
| REF Forces a reference to the symbols identified in the |
| argument list. |
| |
| REPT The statements within REPT-ENDM are repeated according |
| to the result of "expression". [**] |
| |
| SPACE Generates extra line feeds during a listing. |
| |
| SUBTTL Invokes a heading sub-title for listings. |
| |
| TITLE Invokes a heading title for listings. |
| |
| [**] Details are in the section on USING MACROS |
|________________________________________________________________|
Pseudo-OP DB
The "DB" pseudo-OP is used to define a data byte or series of bytes. Its
syntax is:
_____________________________________________________________
| |
| DB n{,n}{,'c'}{,s}{,expression} |
| |
| n defines the contents of a byte at the current |
| reference counter to be "n". |
| |
| 'c' defines the content of one byte of memory to |
| be the ASCII representation of character "c". |
| |
| 's' defines the contents of n bytes of memory to |
| be the ASCII representation of string "s", |
| where "n" is the length of "s". |
| |
| expression is a mathematical expression which evaluates |
| to a number in the range <0-255>. |
|_____________________________________________________________|
The constant declaration "DB" permits the concatenation of its data arguments
using the comma "," as an argument separator. Data values are denoted
according to the specifications in the section on ASSEMBLY LANGUAGE
INFORMATION.
DB 'AB''C'
will produce the character string: 41 42 27 43. This may have been coded as a
complex declaration such as, "'AB',27H,'C'", but the extensive declaration
support in MRAS provides the easier specification.
DB 1,2,'buckle your shoe',3,4,'close the door'
DB 'This is a tes','t'!80H,CR
The hexadecimal expansions of the constant will appear in listings as rows of
eight bytes per row. The expansions may be suppressed from your listings by
using the assembler switch, -NE.
Pseudo-OP DC
This pseudo-OP defines a repetitive constant. Its syntax is:
_____________________________________________________________
| |
| DC quantity,value |
| |
| quantity specifies how many times that "value" is to be |
| repeated as a data byte. It can be defined as |
| any other data definition: n, expression, 'c'. |
| |
| value is the constant to be repeated. As in a "DB" |
| data declaration, the value can be specified |
| as a character, 'c', a numeric value, n, or an |
| expression evaluated to a number in the |
| range <0-255>. |
|_____________________________________________________________|
The pseudo-OP, "DC", will define a repetitive constant and eliminate the
necessity of defining a series of identical data values by long DB
specifications. For example, the following two statements are equivalent:
DB 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
DC 16,0
The latter is much shorter, easier to enter as text, more readable, and takes
up less space in its source form.
DC 100,0
and it will be done. A character constant can also be used for "value" as
illustrated in the following example:
DC 256,'A'
which will set the next 256 storage locations to the letter, "A". Pseudo-OP DS
This pseudo-OP is used to reserve a quantity of storage locations for use by
your program. Its syntax is:
_____________________________________________________________
| |
| DS nn |
| |
| nn reserves "nn" bytes of memory starting at the |
| current value of the reference counter. |
|_____________________________________________________________|
The DS pseudo-OP can also be entered as "DEFS".
FCB DS 32
will define a 32-byte region for later use as a File Control Block. Its origin
can then be referenced as "FCB". The statement,
TABLE DS TABLE_LENGTH * TABLE_WIDTH
will reserve a quantity of storage locations equal to the result of
multiplying the two terms, TABLE_LENGTH and TABLE_WIDTH.
FCB DC 32,0
TABLE DC TABLE_LENGTH * TABLE_WIDTH,0
Pseudo-OP DW
This declaration specifies a 16-bit data value. Its syntax is:
_____________________________________________________________
| |
| DW nn{,'cc'}{,nn} |
| |
| nn defines the contents of a 2-byte word to be |
| the value, "nn". |
| |
| 'cc' defines the contents of a 2-byte word to be |
| the characters, 'cc' |
|_____________________________________________________________|
The DW pseudo-OP can also be entered as "DEFW".
DW 10000,1000,100,10,1
DW 'ab'
DW 'R','o','y'
Note that if a single character is defined as a character constant word, the
low-order byte of the word will contain the character value and the high-order
byte of the word will be set to zero.
Pseudo-OP DATE
The DATE pseudo-OP is used to assemble the system date as an 8-character
string, MM/DD/YY. It's syntax is:
_____________________________________________________________
| |
| DATE |
|_____________________________________________________________|
This actual date is established when you power up your computer and respond to
the DOS's date entry query or by using the DOS's DATE library command. The
date string can be useful to place an ASCII date stamp in your object program
for the purpose of identification as to when it was assembled. See example 1
for an illustration of DATE.
Pseudo-OP DSYM
DSYM is usually used within a macro to assemble the "symbol" argument as if it
were a DB character string. It's syntax is:
_____________________________________________________________
| |
| label DSYM symbol |
| |
| label An optional statement label. |
| |
| symbol A defined symbolic label. |
|_____________________________________________________________|
When used in a macro environment, "symbol" will have the "#" indicator
prefixed to designate the symbol as a macro dummy argument name. An
alternative method is to use the ampersand escape function within a standard
quoted character string such as "DB '&#symbol'" which also assembles to the
same thing in a macro. See example 1 for an illustration of DSYM.
Pseudo-OP DX expression
DX assembles "expression" as a 4-hexadecimal digit character string. Its
syntax is:
_____________________________________________________________
| |
| label DX expression |
| |
| label An optional statement label. |
| |
| expression An expression operand. |
|_____________________________________________________________|
The expression can be a simple symbol or a complicated collection of terms.
The expression is evaluated to a 16-bit value and output as four hexadecimal
digits. See example 1 for an illustration of DX.
Pseudo-OP TIME
The TIME pseudo is used to assemble the system time as an 8-character string,
HH:MM:SS. It's syntax is:
_____________________________________________________________
| |
| TIME |
|_____________________________________________________________|
This actual time is established when you power up your computer and respond to
the DOS's time entry query or by using the DOS's TIME library command. The
TIME string can be useful to place an ASCII TIME stamp in your
object program for the purpose of identification as to when it was assembled.
See Example 1 for an illustration of TIME.
Example 1
3000 00001 ORG 3000H
3000 00002 NAME MACRO #SYM
3000 00003 DSYM #SYM
3000 00004 DX #SYM
3000 00005 ENDM
3000 00006 ENTRY BEGIN
3000 210730 00007 BEGIN LD HL,MSG$
3003 3E0A 00008 LD A,10
3005 EF 00009 RST 40
3006 C9 00010 RET
3007 00011 MSG$ NAME BEGIN
3007+42 00012 DSYM BEGIN
45 47 49 4E
300C+33 00013 DX BEGIN
30 30 30
3010 0D 00014 DB 13
3011 31 00015 DATE
32 2F 33 31 2F 38 34
3019 30 00016 TIME
39 3A 31 31 3A 33 36
0000 00017 END
Pseudo-OP ASEG
This pseudo-OP is used to set the program counter to the absolute segment. The
syntax of "ASEG" is:
_____________________________________________________________
| |
| ASEG |
| ORG expression (optional) |
| |
| expression When evaluated, "expression" will be the |
| origin of the segment. Expression must |
| evaluate to an absolute value. |
|_____________________________________________________________|
It is not necessary for an ORG to follow an ASEG. An ASEG will set the
absolute program counter to the last encountered ASEG value, or to zero if no
previous ASEG had been specified.
Pseudo-OP COMMON
This pseudo-OP is used to set the program counter to a common relative
segment. The syntax of "COMMON" is:
_____________________________________________________________
| |
| COMMON /{name}/ |
| |
| name An optional name which specifies a name |
| for the common segment. |
|_____________________________________________________________|
This pseudo-OP sets the PC to a common relative segment: the slashes are
required. If "name" is omitted, blank common is assumed. A maximum of seven
named commons are permitted in any one module. The "name" of a common cannot
be the same as any symbol. Pseudo-OP CSEG
This pseudo-OP is used to set the program counter to the code relative
segment. The syntax of "CSEG" is:
_____________________________________________________________
| |
| CSEG |
| ORG expression (optional) |
| |
| expression When evaluated, "expression" will be the |
| origin of the segment. Expression must |
| evaluate to an absolute value. |
|_____________________________________________________________|
It is not necessary for an ORG to follow a CSEG. A CSEG will set the code
relative program counter to the last encountered CSEG value, or to zero if no
previous CSEG had been specified. Pseudo-OP DEFL
The "DEFL" pseudo-OP assigns a value to a label. The value is permitted to be
changed during the assembly. The "DEFL" syntax is:
_____________________________________________________________
| |
| label DEFL nn |
| label DEFL expression |
| |
| nn sets the value of "label" to the quantity "nn" |
| |
| expression sets the value of "label" to the evaluated |
| result of "expression". |
|_____________________________________________________________|
This declaration is similar to the "EQU" declaration except that the label
value is permitted to change during the course of the assembly without
producing phase errors (which are generally observed as numerous MULTIPLY
DEFINED SYMBOL errors). If the value of "label" is declared by a "DEFL", the
declaration can be repeated in the program with different values for the same
label. Pseudo-OP DSEG
This pseudo-OP is used to set the program counter to the data relative
segment. The syntax of "DSEG" is:
_____________________________________________________________
| |
| DSEG |
| ORG expression (optional) |
| |
| expression When evaluated, "expression" will be the |
| origin of the segment. Expression must |
| evaluate to an absolute value. |
|_____________________________________________________________|
It is not necessary for an ORG to follow a DSEG. A DSEG will set the
code relative program counter to the last encountered DSEG value, or to zero
if no previous DSEG had been specified.
Pseudo-OP END
The "END" pseudo is used to denote the exit of a *GET, *INCLUDE, or *SEARCH
process. If the END statement of the source file has a non-zero operand, it
will denote the transfer address of the module. Its syntax is:
_____________________________________________________________
| |
| END {nn} |
| END {label} |
| |
| nn Specifies an execution transfer address branch |
| that will be used by the system loader. |
| |
| label Specifies an execution transfer address branch |
| to be the value of "label". |
|_____________________________________________________________|
The "END" statement is used to indicate to the assembler, when the last source
code statement is reached so that any following statements are ignored. If no
"END" statement is found, processing stops when the end of the file is
reached. The END statement can specify a transfer address (i.e. END LABEL or
END 6000H). Only one transfer address should be specified per assembly stream;
however, if more than one non-absolute-zero END operand is detected, only the
first one will be retained. The transfer address is used by the DOS program
execution to transfer control to the address specified in the END statement.
Note that the END statement cannot have a label in the label field of the
statement).
Pseudo-OPs ENTRY, GLOBAL, and PUBLIC
Any one of these may be used to specify that the names of the symbols in the
name list are symbols global to linkage when REL modules are linked by the
linker (MLINK). The syntax is:
_____________________________________________________________
| |
| ENTRY name{,name}... |
| GLOBAL name{,name}... |
| PUBLIC name{,name}... |
| |
| name A symbol to be defined global. |
|_____________________________________________________________|
MRAS treats GLOBAL, ENTRY, and PUBLIC totally equivalent in order to provide
compatibility with other relocating assemblers. A symbol classified as such is
known to other separately assembled modules which specify "name" as EXTRN. All
symbols not specified as GLOBAL, PUBLIC, or ENTRY are known only to the module
currently being assembled.
--------method 1------- --------method 2-------
PUBLIC TRUST
TRUST LD HL,VALUE TRUST:: LD HL,VALUE
Symbols declared PUBLIC in one module that need to be referenced by another
module must be declared EXTRN in all modules other than the module where the
symbol is defined.
Pseudo-OP EQU
This pseudo-OP assigns a constant value to a label. Its syntax is:
_____________________________________________________________
| |
| label EQU nn |
| label EQU expression |
| |
| nn Sets the value of label to nn. |
| |
| expression Sets the value of label to the calculated |
| value of "expression" |
|_____________________________________________________________|
The "EQU" (equate) pseudo-OP is the generally accepted way to define constant
values for use in your program. This declaration serves a different purpose
than the data declarations such as DB, DC, and DW. Data declarations specify
storage locations that contain the values declared. The "EQU" assigns
the value to the label; thus, anywhere the label is used, the assigned value
is utilized. Your programs will be more readable, and easier to maintain if
the values need to be altered in a program revision. Pseudo-OP EXTRN
The EXTRN pseudo-OP is used to declare a PUBLIC symbol which is defined in
some other module. EXT is synonomous with EXTRN. The syntax of "EXTRN" is:
_____________________________________________________________
| |
| EXTRN name{,name}... |
| EXT name{,name}... |
| |
| name A symbol defined external to the current |
| module. |
|_____________________________________________________________|
When your program is made up of more than one REL module linked together by
the linker, symbols which are referenced in a module but defined in another
must be declared EXTRN in all modules which reference the symbol other than
the module which defines it.
Pseudo-OP LORG
The "LORG" pseudo-OP is used to establish a CMD object code file (or part of
one) that loads at an address different from where it will execute. The syntax
of "LORG" is:
_____________________________________________________________
| |
| LORG nn Turn on LORG |
| LORG expression Turn on LORG |
| LORG $ Turn off LORG |
| |
| nn Is the address to start loading the object |
| file (or part of the file). |
| |
| expression When evaluated, "expression" will be treated |
| the same as "nn". |
|_____________________________________________________________|
A load-origin assembler directive, "LORG", is provided to cause the load
addresses of the object file to be based on the LORG operand while the
execution code address references will still be based on the "ORG" operand.
This is useful to construct a module (or part of a module) that will load at
an address different from its execution address. Such is the case when using
MRAS to generate a PROMable module to be used on an external processor
origined at zero. For example:
ASEG
ORG 0000H
LORG 7000H
will assemble code so that absolute address references and the execution
addresses are referenced from X'0000'; however, the object code file will
start loading at X'7000'. Any subsequent "ORG" will maintain the offset
difference established at the previous "ORG" until another "LORG" is detected.
LORG $
to follow the last statement of the offset block of code. The assembler will
specifically test for the case, LORG $, so that it forces a new load block
where one is required. Pseudo-OP NAME
This is used to specify the module name of the generated REL file. The syntax
of "NAME" is:
_____________________________________________________________
| |
| NAME modname |
| NAME ('modname') (equivalent) |
| |
| modname Specifies the module name for the REL file. |
| |
|_____________________________________________________________|
If NAME is not specified in the source stream of an assembly which generates a
REL object code file, a special link item module name record will be generated
using as a default, the first seven non-blank characters of the REL file's
name. The second format is supported for compatability with M-80.
Pseudo-OP ORG
The "ORG" pseudo-OP is used to establish an address for the program counter so
that the address references within a program are designated to origin from
other than address 0000H. The syntax of "ORG" is:
_____________________________________________________________
| |
| ORG nn |
| ORG expression |
| |
| nn sets the address reference counter to the |
| value "nn". |
| |
| expression when evaluated, "expression" will be treated |
| the same as "nn". Terms of "expression" must |
| be defined prior to the "ORG" statement. |
|_____________________________________________________________|
The "ORG" statement is used to tell the assembler at what address to begin
generating the object code for statements which follow. The assembler will
generate object code starting at the address specified by "nn" or
"expression", automatically advancing the program counter by the length of
each instruction or data declaration assembled. The "DS" data declaration
advances the program counter by the amount of storage locations reserved.
Conditional Pseudo-OPs
The "conditional" pseudo-OPs provide a powerful way to maintain a program that
is slightly different when assembled to run on different machine
configurations. Instead of having to maintain multiple copies of a program,
with each having some routines and modifications to make a "custom" version of
the program, by using the conditional pseudo-OPs, you can maintain one set of
source code that has conditional clauses that perform the "customization". It
is very easy to specify which clauses are to be assembled during a particular
assembly. The structure of a conditional clause is as follows:
_____________________________________________________________
| |
| IFxx operand_of_IF |
| . |
| clause |
| . |
| ENDIF |
| |
| THE OPERAND OF THE CONDITIONAL MUST BE DEFINED |
| PRIOR TO THE EVALUATION OF THE "IF" STATEMENT! |
|_____________________________________________________________|
The operand of the "IF" takes on different formats depending on the particular
"IF" pseudo-OP. It can be an expression, a label, or two expressions separated
by commas. If the operand evaluates to a non-zero value, it is interpreted as
a logical TRUE condition. If the argument evaluates to a zero value, it is
interpreted as a logical FALSE condition. When the condition is TRUE, the
conditional clause between the "IF" and the "ENDIF" is assembled. If the
evaluation is to a zero value then the conditional clause is not assembled,
For the sake of uniformity, use the value of "-1" for a logical TRUE and "0"
for a logical FALSE so that, "FALSE EQU .NOT.TRUE" is a valid statment. The
values can be set in program as follows:
TRUE EQU -1
FALSE EQU 0
MOD1 EQU TRUE
MOD2 EQU FALSE
MOD3 EQU FALSE
Conditional clauses can also be nested, in case complicated logical constructs
are needed or in case a conditional clause itself has a conditional
sub-clause. For example:
IF expression1
IF expression2
ENDIF
ENDIF
is a two-level conditional. Conditional clauses can be nested to sixteen (16)
levels although you will rarely find a need for more than three.
IF expression
clause_1.
ELSE
clause_2.
ENDIF
which implies that if expression is TRUE, clause_1 assembles. If expression is
FALSE, then clause_2 will be assembled. The ELSE construct is not required in
a conditional but may be used where you have alternative clauses that can be
based on one switch.
_____________________________________________________________
| |
| ---Type I--- -----Type II------ --Type III-- |
| IF[x] exp IFxx[$] exp1,exp2 IFyy name |
| . . . |
| clause clause clause |
| . . . |
| ENDIF ENDIF ENDIF |
| |
| [x] Optional entry of 1, 2, or 3 to evaluate based |
| on the assembler phase during the assembly |
| |
| xx Can be "LT", "EQ", "GT", or "NE" meaning less |
| than, equal to, greater than, or not equal to |
| respectively when comparing "exp1" to "exp2". |
| |
| [$] The "$" is specified in macro comparisons with |
| the expressions treated as strings (see the |
| section on USING MACROS). |
| |
| yy Can be "DEF", "NDEF", or "REF" representing |
| whether <name> has been defined, undefined, |
| or referenced but undefined; or ABS, REL, EXT, |
| or NEXT representing a test of the mode or |
| class of the symbol. |
|_____________________________________________________________|
Pseudo-OPs IFx - Type I
The IF1, IF2, and IF3 conditional pseudo-OPs evaluate TRUE when the assembler
is on pass 1, 2, and 3 respectively. Pass 1 is the first pass used to evaluate
the value of all symbols. Pass 2 generates the listing and cross reference
data file. Pass 2 will be omitted if -NL is TRUE and -XR is FALSE. Pass 3
generates the object code. Macros must be read in on each pass. EQUates must
be read in on each pass if they are the object of an IFDEF pseudo-OP,
otherwise, they can be read in on the first pass only. In the latter case,
surround the *GET which gets the equate file with an IF1-ENDIF.
Pseudo-OPs IFxx - Type II
Among the Type II constructs, using "IFLT", if the value of expression_1 is
less than the value of expression_2, then the conditional clause will be
assembled. Using "IFEQ", the conditional clause will be assembled only if
expression_1 and expression_2 have equal values. The "IFGT" pseudo-OP will
assemble the conditional clause (i.e. result in a TRUE condition) only if
expression_1 has a value exceeding that of expression_2. The last possibility
is "IFNE", which will cause the assembly of the conditional clause if the
expressions are not of equal value.
IFGT $,MAXADDRESS
ERR Program is too long!
ENDIF
which compares the current value of the program counter (PC) to some
previously specified maximum address. Once the PC exceeds this maximum value,
the condition evaluates TRUE resulting in an assembly of the segment. The
"ERR" pseudo-OP is used to force an assembly error.
Pseudo-OPs IFyy - Type III
Among the Type III constructs, "IFDEF name" will evaluate TRUE if "name" has
been defined prior to the evaluation of the IFDEF on each assembler pass or if
name has been declared EXTRN. "IFNDEF name" will evaluate TRUE if "name" has
NOT been defined prior to the evaluation of the IFNDEF on each assembler pass
nor has it been declared EXTRN. "IFREF name" will evaluate TRUE if "name" has
been referenced but NOT defined prior to the evaluation of the IFREF on each
assembler pass. Suppressing FALSE Conditionals
If during the listing pass, you want to suppress the listing of certain
conditional clauses that are not assembled (i.e. they are evaluated as FALSE),
use the following sequence of operators:
*LIST OFF
IF expression
*LIST ON
clause
*LIST OFF
ENDIF
*LIST ON
With this sequence, the "IF" and "ENDIF" lines will always be suppressed. The
conditional clause will only be listed if the condition being evaluated is
logically TRUE. If no FALSE conditional segment is to be listed, then you may
use the assembler -NC switch which inhibits the listing of all FALSE
conditionals -- including the IF-ENDIF statements.
Pseudo-OP ENDIF
Each IF statement must be matched up with a corresponding ENDIF. The ENDIF is
needed to define the scope of the conditional clause.
Pseudo-OP COM
This pseudo-OP is used to generate a comment record in the object code file of
a directly generated CMD file. Its syntax is:
_____________________________________________________________
| |
| COM <string> |
| |
|
An object deck comment block can be generated within the executable object
code file directly by using the COM pseudo-OP. The comment string must have a
length less than 128 characters. As can be noted, the comment string must be
enclosed in angle brackets. The closing bracket may be omitted. If lower case
characters are desired, then single quotes must surround the angle brackets.
Neither the quotes nor the angle brackets will be a part of the comment
record.
COM '
will produce the comment record which would be viewed if the file were listed.
The generation of the COM object code record will be inhibited if the assembly
is performed using the -CI switch. A binary core-image file can not have a
non-loadable record.
Pseudo-OP ERR
The ERR pseudo-OP is used to force an assembly error. Its syntax is:
_____________________________________________________________
| |
| ERR {message} |
| |
| message is an optional message to inform what is wrong. |
|_____________________________________________________________|
This pseudo-OP forces an immediate warning error and displays the optional
message. It is commonly used in a conditional clause for error trapping.
Pseudo-OP OPTION
This pseudo-OP is used to alter the state of any of the assembler switches
entered on the command line invoking the assembly. Its syntax is:
_____________________________________________________________
| |
| OPTION {-/+}switch{,-/+switch},... |
| |
| -/+] An optional prefix to turn the switch OFF or ON |
| |
| switch Any of the permissable assembler switches. |
|_____________________________________________________________|
Prefix each switch with "-" to turn OFF, or "+" to turn ON (i.e. +NL
suppresses the listing - sets the NO LISTING switch to TRUE). If "+" is
omitted, it is assumed. The COMMA separator is mandatory if you omit the "+".
OPTION switches over-ride command line switches. Pseudo-OP REF
REF may be used to force a reference to the symbol(s) identified in the
argument list. Its syntax is:
_____________________________________________________________
| |
| REF symbol1{,symbol2},... |
| |
| symboln A "name" to be force-referenced. |
|_____________________________________________________________|
This function may be useful to force references to macros so that they may be
loaded via a '*SEARCH' operation.
Listing Pseudo-OPs
Four pseudo-OPs are available to control the assembler listings. These are:
PAGE, SPACE, SUBTTL, and TITLE. Their syntax is:
_____________________________________________________________
| |
| PAGE |
| |
| SPACE n |
| |
| SUBTTL <string> |
| |
| TITLE <string> |
| |
| n Specifies how many line feeds to generate. |
| |
| <string> Is the title or sub-title string to appear in |
| the listing headings. |
|_____________________________________________________________|
A new page can be forced to provide separation of routines, functions, etc. by
using the PAGE pseudo-op. This pseudo-OP will be ignored if it appears between
*LIST OFF and *LIST ON. PAGE statements are automatically suppressed from the
listing. PAGE will output a FORM FEED character only during the listing pass.
TITLE '<This is an UC/lc title>'
The first TITLE pseudo-OP found in the text will be used for titling.
All other TITLE pseudo-ops will be ignored.
Assembler Directives
MRAS supports seven assembler directives. In contrast to source statements
which are translated to machine language, these directives are "conversation"
to the assembler. Each directs the assembler to behave in a particular manner
or perform a specific function. The directives do not generate any machine
language code by themselves, they merely act as "commands" to the assembler.
Each "command" must start in column one of a source statement line, and must
start with either an asterisk "*" or a period ".". The entire directive word
may be entered, or it may be abbreviated to its minimum unique character
string. The assembler directives are:
_____________________________________________________________
| |
| *Get file Causes the assembler to begin reading source |
| code from the "file". |
| |
| *Inc file Causes the assembler to begin reading source |
| code from the file identified on the command |
| line via "+I=filespec". Treated as *GET if no |
| "+I=filespec" was specified. |
| |
| *List OFF Causes the assembler listing to be suspended, |
| starting with the next line. |
| |
| *List ON Causes assembler listing to resume, starting |
| with this line. |
| |
| *Mod exp Advances the "module" character substitution |
| string. |
| |
| *RAdix exp Changes the default radix to expression which |
| must evaluate to the range <1-16>. |
| |
| *REquest Generates a Special Link Item to request a |
| search by the linker of the library file |
| identified in the *REQUEST directive. |
| |
| *Search lib Invokes an automatic search of the Partitioned |
| Data Set (PaDS) "lib" to resolve any undefined |
| references capable of being resolved by PaDS |
| assembler source member modules. |
|_____________________________________________________________|
*GET filespec
This directive invokes assembly from a source disk file. Its syntax is:
_____________________________________________________________
| |
| *Get filespec/ASM |
| |
| filespec Causes the assembler to begin reading source |
| code from the file, "filespec". |
|_____________________________________________________________|
This directive tells the assembler to temporarily switch its source assembly
to the file identified as "filespec", and use it to continue the assembly. A
default file extension of "ASM" will be used if none is provided in the
directive statement. The file itself can be headered and/or numbered, as MRAS
will automatically detect its type and adjust accordingly; however, all source
files must be similarly structured. When the end-of-file is reached, or an
assembly language "END" statement is read, assembly resumes from the next
statement following the statement which invoked the "*GET". *INCLUDE filespec
This directive invokes assembly from a source disk file. Its syntax is:
_____________________________________________________________
| |
| *Include filespec/ASM |
| |
| filespec Causes the assembler to begin reading source |
| code from the file identified on the command |
| line via "+I=include" |
|_____________________________________________________________|
This directive tells the assembler to temporarily switch its source assembly
to the file identified on the MRAS command line via the "+I=include" file
switch. If no "+I=" file switch was entered, the *Include is treated exactly
as if it were a "*Get filespec."
LIST ON/OFF
This is used to suppress the listing of blocks of code. Its syntax is:
_____________________________________________________________
| |
| *List off/on |
| |
| OFF Causes the assembler listing to be suspended, |
| starting with the next statement. |
| |
| ON Causes assembler listing to resume, starting |
| with this statement. |
|_____________________________________________________________|
The pair of directives, "*LIST OFF" and "LIST ON", can be used to suppress the
listing of a block of code. All statements which follow a "*LIST OFF" will be
suppressed during the listing pass. The "*LIST ON" will resume standard
listing. An exception to the suppression is that any assembler source
statement containing an assembly error will be listed along with its
appropriate error message. In this manner, you can use an "*LIST OFF"
directive at the beginning of your assembly source (to suppress all listing)
and lines containing errors will be forced to be displayed.
*MOD
This directive increments a character substitution string to simulate local
labels in blocks within one module. Its syntax is:
_____________________________________________________________
| |
| *MOD |
| Advances the "module" character substitution |
| string. |
|_____________________________________________________________|
The *MOD directive will increment a string replacement variable each time the
directive is executed. The string will replace the question mark, "?",
character in labels and label references found in any statement. Its use is
essentially applicable to subroutine libraries where duplication of labels
could occur. By specifying the *MOD directive as the first statement of each
module of code and by using a question mark in labels, you can construct
source subroutine libraries for use in your programs without having to worry
about duplicate labels occuring. Unless at least one *MOD statement is
specified, the question mark will not be translated. *RADIX expression
This directive sets the default radix for all numeric terms except for "*RADIX
expressions" which always default to 10. Its syntax is:
_____________________________________________________________
| |
| *RAdix expression |
| |
| expression Is evaluated and becomes the new default radix |
| for all numeric terms. The value of expression |
| must be in the range <1-16>. |
|_____________________________________________________________|
Note that in the evaluation of the expression for the *RADIX directive, the
assembler will always use a radix default of 10. The assembler defaults to a
radix of 10 unless overridden by a *RADIX directive.
*REQUEST lib1{,lib2},...
This is used to convey information to the linker. It will generate a "Request
Library Search" special link item for use by MLINK. The syntax is:
_____________________________________________________________
| |
| *REquest lib1{,lib2},... |
| |
| libn The 1-7 character name of the REL library to |
| be searched by the linker. |
|_____________________________________________________________|
*REQUEST will generate the link item to the linker for each library name
identifed in the argument list.
*SEARCH filespec
This directive is used to invoke an automatic search of a Partitioned Data Set
(PaDS) source library, "filename/LIB", for all members that will resolve
undefined references in the source stream. This provides a source library
structure. *SEARCH will require two (2) levels of "*GET" nesting. Also, a
*SEARCH member cannot use a *GET directive or another *SEARCH directive. The
default file extension for searched files is "LIB". The syntax of *SEARCH
filespec is:
_____________________________________________________________
| |
| *Search filespec/LIB |
| |
| filespec Invokes an automatic search of the PaDS |
| "filespec/LIB" to resolve any undefined |
| references capable of being resolved by |
| PaDS assembler source member modules. |
|_____________________________________________________________|
The PaDS source library constitutes members composed of one or more routines.
Each routine should have its routine name (the label field entry) in the PaDS
member directory. This is accomplished by naming the source file to be
appended to the library the same name as the routine or by appending using a
MAP. Details on constructing and using Partitioned Data Sets is included with
PaDS documentation. The PaDS utility is available separately.
Member definition error: filespec(member)
After the member's source code is read, MRAS will continue to search the PaDS
library until it exhausts all members. There are no restrictions on the order
of members. Routines in one member can reference other members with complete
disregard as to any ordering of entries in the PaDS.
; Entry for routine entitled "MOVE"
IFREF MOVE
MOVE . ;Routine of code
.
ENDIF
; Entry for routine entitled "SHIFT"
IFREF SHIFT
SHIFT . ;Routine of code
.
ENDIF
If your source code references "SHIFT" but not "MOVE", as long as both "SHIFT"
and "MOVE" are member entries in the PaDS library, a *SEARCH of the library
will access the member and assemble only the SHIFT routine.
What is a MACRO?
In virtually all programs, you find particular sequences of code that are
repeated. These sequences may be termed routines. They could be so short that
the overhead needed to set them up as CALLable routines is ineffective. Or,
they could be longer routines that just cannot be constructed as CALLable
segments. You may even want a code sequence to be an in-line assembly in
contrast to a CALLable routine for the purpose of fast execution. The most
useful function is to be able to have parameterized routines - algorithms that
operate on different values each time the algorithm is invoked.
LD HL,VALUE
LD (MEMORY),HL
How many times is this little sequence repeated in your programs? Five? Ten?
If we set up a macro near the beginning of our program that looked something
like this:
STOR MACRO #VAL,#MEM ;Macro to store "VAL" into memory
LD HL,#VAL ;Get value into HL
LD (#MEM),HL ;Load value into memory
ENDM ;End of the macro
we could perform the above two statements with one macro call as follows:
STOR VALUE,MEMORY ;Invoke the macro
The first part of the example, defines a macro called "STOR". This is done
exactly once per program! If we save our macros in a macro source file, each
of our programs could "*GET MACROS"; thus, we would not have to even manually
enter the macro into each program. MACRO Definition
The format for a macro definition is illustrated as:
_____________________________________________________________
| |
| MOVE MACRO #parm1,#parm2=dflt2,#parm3 |
| LD HL,#parm1 |
| LD DE,#parm2 |
| LD BC,#parm3 |
| LDIR |
| ENDM |
|_____________________________________________________________|
The macro definition consists of three parts: a macro prototype, a macro
model, and the ENDM statement. The prototype is used to specify the macro name
and the dummy parameter names used in the model. Default substitutions may be
specified in the prototype to be used if the corresponding parameter is not
passed in the macro invocation. The macro model contains all of the assembler
statements to be generated when the macro is invoked. The model is sometimes
called the macro skeleton or template. The dummy parameter names occupy the
positions where the actual parameters will be placed by the macro processor in
MRAS. The third part, the ENDM statement, is used to indicate the end of the
macro model. Macro Prototype
Macros are named just like symbolic labels. The same rules apply. The number
sign "#" is used to denote a parameter in the macro prototype; however, its
use is optional. It is still required in the macro model to indicate the start
of a parameter name. The length of macro names can range from <1-15>.
Special characters <@, $, _> may be used in the name construct. Do not
use the question mark in macro names as it would conflict with the symbol
substitution string use made of "?".
_____________________________________________________________
| |
| mname MACRO {#parm1}{=dflt1}{,#parm2{=dflt2}}{,...} |
| |
| mname is the macro name used to invoke the macro. |
| |
| #parmn are dummy parameters of the macro which will |
| be replaced by actual parameters during the |
| macro invocation. "#" is an optional prefix. |
| |
| dfltn are optional default strings to be used for |
| the dummy parameters when a parameter is not |
| provided in the macro invocation. |
|_____________________________________________________________|
The upper limit on the number of macro parameters is 127; however, you can not
exceed the length of a standard assembler source statement. Thus, the
statement length becomes the limiting factor. As is the case with macro names,
the rules for naming dummy parameters are identical to the rules for labels.
If a macro parameter is enclosed in angle brackets, the entire string which is
enclosed within brackets will be treated as one parameter - even if it
contains separator characters. Neither the macro names nor the "dummy" names
are included in the symbol table generated by MRAS, thus there is no
restriction on reusing the same name as a "dummy" for a label; however, to
avoid confusion, it is recommended that you avoid using dummy names as
symbolic label names.
5200 00002 FEED MACRO #STRING
5200 00003 $?1 JR $?2
5200 00004 LABEL? IRPC XX,#STRING
5200 00005 LABXX DB '&XX'
5200 00006 IFGT $-LABEL?,3
5200 00007 EXITM
5200 00008 ENDIF
5200 00009 ENDM
5200 00010 $?2 LD HL,LABEL?
5200 00011 ENDM
5200 00012 FEED 012345
5200+1806 00013 $A1 JR $A2
00014 LABELA IRPC XX,012345
5202+ 00015 LABXX DB '&XX'
5202+ 00016 IFGT $-LABELA,2
5202+ 00017 EXITM
5202+ 00018 ENDIF
5202+ 00019 ENDM
5202+30 00020 LAB0 DB '0'
00021 IFGT $-LABELA,2
00022 EXITM
00023 ENDIF
5203+31 00024 LAB1 DB '1'
00025 IFGT $-LABELA,2
00026 EXITM
00027 ENDIF
5204+32 00028 LAB2 DB '2'
00029 IFGT $-LABELA,2
00030 EXITM
00031 ENDIF
5205+210252 00036 $A2 LD HL,LABELA
0000 00037 END
Macro Model
Any valid Z-80 statement, MRAS pseudo-OP, or assembler directive (except *GET
or *SEARCH) is valid in the macro model.
ENDM pseudo-OP
This pseudo-OP is used to specify the scope of a macro model. It is used much
like ENDIF. Its syntax is:
_____________________________________________________________
| |
| mname MACRO parms |
| model statements |
| ENDM |
|_____________________________________________________________|
The ENDM pseudo-OP must be used to let the macro processor know what is the
last macro model statement. If macros are nested, each must have an ENDM.
EXITM Pseudo-OP
This pseudo-OP can be used to prematurely exit from a MACRO expansion. This is
normally used within a conditional clause. One level of conditional nesting
will be removed (if any are present). See the example for IRP.
Macro Definition Examples
This macro will move a block of memory from one location to another. If the
"length" parameter is omitted, then a value of "255" will be used:
MOVBLK MACRO #FM,#TO,#LEN=255
LD HL,#FM
LD DE,#TO
LD BC,#LEN
LDIR
ENDM
This is a macro to clear a region of memory (i.e. set to 0). This macro will
invoke the MOVBLK macro in a nested invocation:
CLRMEM MACRO #BUF,#LEN=255
LD HL,#BUF
LD (HL),0
MOVBLK #BUF,#BUF+1,#LEN
ENDM
This macro will add the 8-bit register "A" to 16-bit register pair "HL":
ADDHLA MACRO
ADD A,L
LD L,A
ADC A,H
SUB L
LD H,A
ENDM
A macro is not required to contain dummy parameters as is evidenced by the
last example.
Incorporating Conditionals
Conditional pseudo-OPs can be specified in macro models. For instance, say you
want the MOVBLK macro to be able to perform a non-destructive move (a
destructive move would be where the destination is an address between "from"
and "from+length-1"). You can insert conditional pseudo-OPs to test the
parameters during the assembly of the expansion. Don't forget that the actual
labels substituted for parameters must be defined prior to invoking the MACRO!
Then, only certain segments of the macro will be assembled according to the
result of the evaluation. Analyze the following example:
MOVBLK MACRO #FM,#TO,#LEN=255
IFNE #FM,#TO ;Don't expand if #FM=#TO
LD BC,#LEN ;Establish the length
IFGT #FM,#TO ;Do we LDIR or LDDR?
LD HL,#FM ;#FM > #TO => LDIR
LD DE,#TO
LDIR
ELSE
LD HL,#FM+#LEN-1 ;#TO > #FM => LDDR
LD DE,#TO+#LEN-1
LDDR
ENDIF
ENDIF
ENDM
MACRO Nesting
The CLRMEM example depicts a macro that nests a macro invocation. Macros may
be nested to seven (7) levels. That is, at any time, macro expansions for 7
macros called in a chain can be pending. For example:
ABC MACRO #PARMS,...
(model statements)
MOVE parm,parm ;call macro "MOVE"
(model statements)
ENDM
MOVE MACRO #parm1,#parm2,#parm3
(model statements)
ENDM
is perfectly legal. The expansion of the "MOVE" macro is not performed during
the definition of the "ABC" macro but rather during the invocation of "ABC".
ABC MACRO #PARM
(model statements)
XYZ MACRO #PARMs,...
(model statements)
ENDM
ENDM
is a legal macro definition. The inner macro (XYZ) will not be defined until
the outer macro (ABC) is invoked. Note the two ENDM statements. MACRO Invocation
The invocation of a macro is termed a macro "call". The macro processor then
proceeds to replace the call with the model statements specified when the
macro was defined. The replacement of the macro call by the macro model
statements is termed the macro "expansion". Positional Parameters
"Positional" parameters are correlated by the position they appear in the
macro call. For example, if the "MOVBLK" macro was called with:
MOVBLK VIDEO,CRT_BUFFER,CRT_SIZE
then the substitution string "VIDEO" would replace every appearance of "#FM",
the string "CRT_BUFFER" would replace every appearance of "#TO", and
"CRT_SIZE" would replace the dummy parameter, "#LEN". Note that actual strings
are positionally correlated with the positions of the dummy parameters in the
macro prototype.
SHIFT 4200H,,100H
omits the middle of three parameters. Generally, a default would have been
provided in the macro definition.
Keyword Parameters
If the number of parameters is large, it is sometimes burdensome to remember
the order of the parameters, or to provide the correct number of commas if a
series of parameters are omitted. These drawbacks are remedied by the use of
"keyword" parameters. The macro call parameter list can identify the actual
parameters by using the name of the dummy parameter as well. The keyword
syntax is:
_____________________________________________________________
| |
| #dummy=actual parameter |
| |
| mname #parm2=actual2,#parm3=actual3 |
|_____________________________________________________________|
If the previous macro call was invoked by keyword parameter specification, it
could look something like this:
SHIFT #LEN=100H,#FM=4200H
Mixing Positional and Keyword Parameters
A single macro invocation can intermix both positional and keyword parameters.
The point that needs clarification, is what positions are actually denoted in
the parameter list. It is simply treated. In a mixed parameter list, keyword
parameters are ignored when considering place positions. For example, in the
following macro call:
SHIFT #LEN=100,BLOCK,BUF_START
even though the length parameter appeared first in the parameter list, since
it was designated as a keyword, it is ignored from the positional count and
"BLOCK" is the first parameter with "BUF_START" second. In a similar manner:
COMP PARM1,#P6=2,,PARM3,#P8=38,PARM4
"PARM1" is in position one, the second parameter is omitted (the double
comma), "PARM3" and PARM4" are in the third and fourth positions respectively.
The sixth and eighth parameters have been entered by keyword. Local Labels
So far, all of the examples have shown macro models without labels. What would
happen if we had a macro defined as follows:
FILL MACRO #CHAR,#NUM
LD B,#NUM
FLP LD (HL),#CHAR
INC HL
DJNZ FLP
ENDM
We would have a problem because every time the macro was called, the label,
"FLP", would be used. If "FILL" was invoked more than once, the assembler
would generate MULTIPLY DEFINED SYMBOL errors on each expansion. We have to be
able to use labels, but we need to find a way to be able to make "unique"
labels on each macro expansion. String Comparisons
It is sometimes desirable to be able to test within a macro model, the exact
string passed as a parameter. Four conditional pseudo-OPs have been added
strictly for string comparisons within macro processing. These are:
_____________________________________________________________
| |
| IFLT$ string1,string2 TRUE if string1 < string2 |
| |
| IFEQ$ string1,string2 TRUE if string1 = string2 |
| |
| IFGT$ string1,string2 TRUE if string1 > string2 |
| |
| IFNE$ string1,string2 TRUE if string1 <> string2 |
|_____________________________________________________________|
These pseudo-OPs provide TRUE/FALSE evaluation in the comparison of string1 to
string2 (like the non-"$" pseudo-OPs do with mathematical expressions).
Obviously, hard encoding of both string1 and string2 would be nonsense! Aha,
he said... If we use a macro dummy parameter, it will be substituted by the
actual parameter string passed in the macro call expansion. This means that
the macro itself can test the parameter string in a limited manner. For
example:
IFNE$ #TO,(DE)
LD DE,#TO
ENDIF
as part of a macro model, will have the "#TO" replaced during the expansion.
The test becomes dynamic! The dummy parameter can be either string1 or string2
- it doesn't matter. Testing String Lengths
Another feature available in the macro processor is the per cent sign "%"
operator. This operator is used to recover the length of the passed parameter
string and the number of parameters passed in the macro call. Note that the
limitation for the use of the "%" operator, is that it is acceptable only for
parameters of the current macro expansion. That means that you can't test for
lengths outside of the current macro if you are nesting macro calls (macros
cannot be recursive!). The operator can be used like these examples:
LD B,%#PARM ;loads B with the length of #PARM
IFGT %#PARM1,6 ;Restricts parm1 to a length <1-6>
ERR Parm too long!
ENDIF
IFLT %%,4 ;This macro requires 4 actual parms
ERR Missing required parameters!
ENDIF
The "%%" operator will return the number of parameters passed in the current
Macro call. When a dummy parameter name (including the "#" prefix) follows the
per cent operator, the length of the parameter string is returned. Concatenating MACRO Labels
You can concatenate a string to a dummy parameter name by connecting it with
the concatenation operator, "%&". For instance, the model statement:
IFREF #NAME%&L
will have the "#NAME" replaced by the MACRO call substitution string appended
with the letter "L".
Special in-line MACROs
MRAS supports the standard INTEL macro operations of REPT, IRPC, and IRP.
These macro operations immediately expand the model statements according to
specifications in the macro prototype statement. They may also be an interior
macro of a nested macro definition.
Macro REPT
The statements within REPT-ENDM are repeated according to the result of
"expression". The syntax of this macro is:
label REPT <expression>
statements
ENDM
In the prototype statement, the angle brackets are not required. See the
following example which generates values from 1 through n where "n" is
controlled by the value passed as "#COUNT" in the DOIT invocation.
5200 00002 DOIT MACRO #COUNT
5200 00003 T DEFL 0
5200 00004 REPT #COUNT
5200 00005 T DEFL T+1
5200 00006 DB T
5200 00007 ENDM
5200 00008 ENDM
5200 00009 DOIT 3
0000+ 00010 T DEFL 0
00011 REPT 3
5200+ 00012 T DEFL T+1
5200+ 00013 DB T
5200+ 00014 ENDM
0001+ 00015 T DEFL T+1
5200+01 00016 DB T
0002+ 00017 T DEFL T+1
5201+02 00018 DB T
0003+ 00019 T DEFL T+1
5202+03 00020 DB T
Macro IRPC
The statements within IRPC-ENDM are repeated for each character in the
character list while the "identifier" is replaced with each character in turn
from the identifier list. The identifier can be a multi-character string which
is not a reserved word. This macro's syntax is:
label IRPC identifier,character-list
statements
ENDM
See the following example which generates values from 1 to 3.
00002 IRPC X,123
5200 00003 DB X
5200+ 00004 ENDM
5200+01 00005 DB 1
5201+02 00006 DB 2
5202+03 00007 DB 3
Macro IRP
The statements within IRP-ENDM are repeated for as many items as are in the
argument list with "dummy" being replaced by each argument in turn. The angle
brackets surrounding the argument list are mandatory. Its syntax is:
label IRP <dummy>,<arg1,arg2,...,argn>
statements
ENDM
where label is an optional statement label. See the following example which
generates values from 1 to 3 and makes use of the EXITM escape.
00003 LABEL IRP XX,<1,2,3,4,5>
5200 00004 LABXX DB XX
5200 00005 IFGT $-LABEL,3
5200 00006 EXITM
5200 00007 ENDIF
5200+ 00008 ENDM
5200+01 00009 LAB1 DB 1
00010 IFGT $-LABEL,3
00011 EXITM
00012 ENDIF
5201+02 00013 LAB2 DB 2
00014 IFGT $-LABEL,3
00015 EXITM
00016 ENDIF
5202+03 00017 LAB3 DB 3
00018 IFGT $-LABEL,3
00019 EXITM
00020 ENDIF
General
MRAS recognizes two types of errors. These are:
_____________________________________________________________
| |
| DOS This is an operating system disk I/O error. |
| The error message is displayed and control is |
| returned to DOS. |
| |
| Assembler These errors may occur while executing an |
| Assemble command. There are three types: |
| terminal, fatal, and warning. |
|_____________________________________________________________|
Disk I/O errors can be received during an assembly. When an I/O error occurs,
the assembly will be aborted and control will be returned to DOS.
_____________________________________________________________
| |
| Terminal Assembly is terminated and control is returned |
| to command mode. |
| |
| Fatal Processing of the line containing the error is |
| immediately stopped and no object code is |
| generated for that line. Assembly proceeds |
| with the next statement. |
| |
| Warning The error message is displayed and assembly of |
| the line containing the warning continues. The |
| resulting object code may not be what the |
| programmer intended. |
|_____________________________________________________________|
Following is a list of all error messages and an explanation of each. DOS Errors
The standard DOS error messages will be displayed if the DOS returns an error
code after return from any disk operation. Consult your DOS operating manual
for explanations of those errors. If an I/O error is detected during an
assembly, the long form of the error message will be displayed. This provides
an observance as to which file was affected by the I/O error. Terminal Errors:
Symbol table overflow
There is not enough memory for the assembler to generate your program's symbol
table or macro storage. You have one option: divide your program into two or
more relocatable modules and assemble each separately then link with the
linker.
*GET or *SEARCH error
A "*GET filespec" or "*SEARCH library" assembler directive was found in a
library member. A searched library cannot have "*GETs" or nested "*SEARCHes".
Member definition error: filespec(member)
This is a result of a fetched *SEARCH member not resolving the symbol
reference invoking its fetch.
Fatal Errors:
Bad label
The character string found in the label field of the source statement does not
match the criteria specified under SYMBOLIC NAMES.
Expression error
The operand field contains an ill-formed expression.
Illegal addressing mode
The operand field does not specify an addressing mode which is legal with the
specified OPCODE.
Illegal opcode
The character string found in the opcode field of the source statement is not
a recognized instruction mnemonic, assembler pseudo-op, or MACRO name.
Missing information
Information vital to the correct assembly of the source line was not provided.
The OPCODE is missing or the operands are not completely specified.
Too many nested *GETs
*GET filespec nesting exceeds the number of levels supported. The *GET will be
ignored.
Unclosed conditional
The "END" statement or end of source was reached and an open "IF" conditional
block was still pending. Your program is missing the closing "ENDIF".
ENDIF without IF
An "ENDIF" pseudo-op was detected without a corresponding conditional "IF" or
"IFxx" in effect. The "ENDIF" will be ignored.
ELSE without IF
An "ELSE" statement was detected without a preceding "IF" conditional segment.
Filespec required
A *GET or *SEARCH directive was detected but the statement did not contain
the required file specification. The *GET or *SEARCH will be ignored.
Bad parameter(s)
When output preceding a MACRO definition, it implies an error in the
parameters of a MACRO.
Nested MACRO ignored
A macro definition statement was nested in the model of another macro.
Missing MACRO name
The name field of the macro definition statement did not contain the macro
name. The macro will not be defined.
ENDM without MACRO
An ENDM pseudo-OP was detected while not in a macro definition phase. It will
be ignored.
Too many parameters
In a macro call, the number of parameters passed exceeded the number defined
for the macro. The macro call will not be expanded.
Too many nested MACROs
The number of pending nested macro calls exceeds the current nest level
supported. The macro call will not be expanded.
MACRO forward reference
A macro call was detected prior to the definition of the macro. The macro call
will not be expanded since gross phase errors would result.
Multiply defined MACRO
A macro definition statement was detected for a macro already defined. The
subsequent definition will be ignored.
Warnings:
Branch out of range
The destination of a relative jump instruction (JR or DJNZ) is not within the
proper range for that instruction. The instruction is assembled as a branch to
itself by forcing the offset to hex X'FE'.
Field overflow
A number or expression result specified in the operand field is too large for
the specified instruction operand. The result is truncated to the largest
allowable number of bits. This error would also be output during a global
change if a resultant line would exceed 128 characters.
Multiply defined symbol
The operand field contains a reference to the symbol which has been defined in
another line. The first definition of the symbol is used to assemble the line.
Multiple definition
The source line is attempting to illegally redefine a symbol. The original
definition of the symbol is retained. Symbols may only be redefined by the
DEFL pseudo-OP and only if they were originally defined by DEFL.
Undefined symbol
The operand field contains a reference to a symbol which has not been defined.
A value of zero is used for the undefined symbol.
Invoking MLINK
MLINK is used to link one or more relocatable modules to generate an
executable program file. MLINK is easily invoked interactively or from a Job
Control Language (JCL) by the syntax:
________________________________________________________________
| |
| MLINK {filespec}{,filespec}... {switch}{switch}... |
| |
| filespec - One or more relocatable modules to load. |
| |
| switch - any valid MLINK switch as follows: |
| |
| -A={y/N} - Specify that MLINK is to abort or not abort |
| upon an error in the command processing. |
| Default=N. |
| |
| -C=address - Specify the hexadecimal origin of the common |
| blocks for succeeding modules loaded. |
| |
| -D=address - Specify the hexadecimal origin of the data |
| segment for succeeding modules loaded. |
| |
| -E - Exit to DOS; Save CMD file if modules loaded. |
| -E=symbol - Same as -E but use symbol as entry point. |
| |
| -H={y/N} - Generate 05 record header from 1st module's |
| name. Default=N. |
| |
| -I={y/n} - Generate a core-image '/CIM' file. Default=N. |
| |
| -L=address - Specify the hexadecimal link origin of all |
| blocks not switched by -P, -D, or -C |
| |
| -M - List all defined symbols (3 per line). |
| -M=filespec - List defined symbols to filespec (1 per line).|
| |
| -N=filespec - Specify /CMD file generation. |
| -N=:d - Specify /CMD file generation. Use default |
| filename for filespec. |
| |
| -O - Handling for overlays - See overlay section. |
| |
| -P=address - Specify the hexadecimal origin of the program |
| segment for succeeding modules loaded. |
| |
| -Q={wxyz} - Specify generation order of segment classes |
| in the /CMD file generated [A,P,D,C]. |
| -Q - Reset segment classes to link origin. |
| |
| -R - Reset and clear all tables. |
|________________________________________________________________|
________________________________________________________________
| |
| -S=filespec - Search referenced library to resolve any |
| undefined globals. |
| |
| -U - List undefined symbols. |
| |
| -V=filespec - Use virtual memory file for stream buffering. |
| -V=:d - ditto; filename generated is MLINK/VMF:d. |
| |
| -X - Equivalent to -E |
| |
| -Y=<text> - Used to specify the text for a 1F load module |
| record (a comment record). |
| |
| -Z={y/N} - Generate hex zeroes for DS regions in DSEGs |
| and COMMONs. This switch defaults to N. |
|________________________________________________________________|
Command input
Filespecs and switches can be intermixed on a single line by separating
filespecs with either a switch prefix, a comma, or a space. A plus sign '+' or
a minus sign '-' can be used as the switch prefix. Any character string not
starting with a switch prefix will be interpreted as a file which contains a
relocatable module or modules to load into the linker. The /REL extension will
be automatically assumed. If a file contains more than one module, each module
will be processed and loaded. If any symbol is detected as being defined at
more than one address during the loading of a module, you will be notified of
the symbol name and processing will continue. This may occur when one or more
symbols of more than seven characters have been truncated to a length of seven
and are thus no longer unique. Status messages
At the initiation of the '?' prompt for more input, a status line will list
the number of free bytes remaining in the buffer area in the format:
ddddd free space (ddddd in decimal)
The segment origin address, end address, and length (all in hexadecimal) will
also be listed for any segment chains loaded. Segment chains are either
Program (P), Data (D), or Common (C) for segments loaded after a -P, -D, or -C
switch respectively. The "Program" segment results from a CSEG or code
segment. "P" is used in the linker so as to be able to differentiate from the
single letter "C" used to designate the COMMON segment. All other segments
loaded without a respective switch will be stored classified as being in the
Link Origin chain and will be designated by the letter, "L". The format of the
status will be:
a
where "a" = L, P, D, or C; "ssss" = the chain's lowest origin; "eeee" = the
chain's highest load address; "llll" = the chain's length calculated from
"llll=eeee-ssss+1". MLINK switches:
MLINK switches control various aspects of the linker. Some of the switches
include a parameter which may be optional. A switch parameter is connected to
its switch by either the '=' or ':' separator.
Switch -A={y,N}
Upon detecting an error, MLINK will normally recycle to the '?' command prompt
to await a new command. If you wish an immediate exit on a detected error,
then this switch can be used to tell MLINK to abort or not abort upon an error
in the command processing. Its use is recommended for JCL invocation of the
linker. The switch defaults to NO.
Switch -C=address
MLINK provides the capability of separating the code, data, and common
segments to origins of your choosing. Any not switched are origined according
to the link origin (see the -L switch). Use this -C switch to specify the
hexadecimal origin of the common blocks for succeeding modules loaded. Note
that the switch does not take effect on any module already loaded.
Switch -D=address
MLINK provides the capability of separating the code, data, and common
segments to origins of your choosing. Any not switched are origined according
to the link origin (see the -L switch). Use this -D switch to specify the
hexadecimal origin of the data segment for succeeding modules loaded. Note
that the switch does not take effect on any module already loaded.
Switch -E{=symbol}
This switch is used to generate the executable program file (/CMD) if any
modules had been loaded then exit to DOS. If any symbol is left undefined (or
some other error is detected), MLINK will terminate the -E switch processing
and recycle to the '?' prompt. You may exit via <BREAK> or "-R-E". If
you wish to designate one of the PUBLIC symbols as the entry point to the
program, use the '-E=symbol' syntax. This will override any entry point which
was designated via an END statement.
Switch -H={y/N}
This switch is used to have MLINK generate a 05 object file record header when
the executable program is output. The header name is derived from the first
loaded module's name. Switch -H defaults to "N".
Switch -I={y/N}
This switch is used to specify that MLINK should generate a core-image '/CIM'
object file in lieu of a load format program file. -I defaults to N.
Switch -L=address
MLINK provides the capability of separating the code, data, and common
segments to origins of your choosing. Any not switched are origined according
to the link origin. The link origin defaults to 3000H for TRSDOS 6.x and 5200H
for Model I/III operation. If you wish to designate another link origin for
all blocks not switched by -P, -D, or -C, specify the hexadecimal link origin
via this -L switch. Note that the switch does not take effect on any module
already loaded.
Switch -M{=filespec}
This switch is used to list all defined symbols at three per line. Any symbol
defined at more than one address (multiply defined) will be indicated by the
appendage of an asterisk. If you enter a filespec parameter, the list of
defined symbols will be written to the designated file at one per line.
Switch -N=filespec {-N=:d}
This switch is used to request the /CMD file generation. It may be entered
anytime during the entry of link commands. If you use the syntax of "-N=:d",
the generated /CMD file will use the default filename for filespec which will
be the same name as the first REL module loaded. This syntax requires that at
least one REL module is loaded prior to entry of the -N=:d.
Switch -O
This switch schedules the series of modules loaded since the last -O switch
for generation as an overlay file. The first series of modules loaded will be
the root program. See the section on overlays for more information.
Switch -P=address
MLINK provides the capability of separating the code, data, and common
segments to origins of your choosing. Any not switched are origined according
to the link origin. Use this switch to specify the hexadecimal origin of the
program segment for succeeding modules loaded. Note that the switch does not
take effect on any module already loaded.
Switch -Q={wxyz}
During the generation of the output object file, the byte stream is output by
module segments in the order of the modules loaded. If you have switched any
of the segment origins via the -P, -D, or -C switches, you may want to
redesignate the specific order of the segments being output. Specify the
generation order of segment classes in the output file generated via this -Q
switch. Denote the segment class via: A, P, D, or C for absolute, program,
data, and common respectively. Any segment class not sequenced by your entry
will automatically be output in the sequence APDC. Note that a maximum of four
entries are permitted and no two may be duplicated. Switch -R
This switch is used to reset and clear all tables MLINK had internally
developed. Any open VM file will be deleted. Use -R when you wish to
reconstruct a set of modules using different origins. If you wish to terminate
the link session after you have loaded modules, you can reset the linker with
-R then issue the -E switch..
Switch -S=filespec
You can manually request the linker to search a library of modules created
with the MLIB librarian so as to resolve undefined globals. Do NOT enter a
file extension with the filespec. The library search facility of MLINK is
capable of searching either a /REL library or an /IRL library. MLINK will
first assume a RELocatable structured (REL) library. If a REL library is not
found, then an Indexed ReLocatable (IRL) library will be assumed. If an IRL
library is not found, the "File not found" error will be issued. The -S switch
processing must assign its own extension to be able to properly select REL
searching or IRL indexed searching!
Switch -U
This switch will cause the listing of all symbols currently undefined. Unlike
the -M switch, the list of undefined symbols cannot be redirected to a disk
file.
Switch -V=filespec {-V=:d}
As relocatable modules are loaded, their code, data, and common segments are
stored in memory (the available buffer pool starts immediately after the
linker and extends to the memory address noted as HIGH$ by the DOS). The
linker also maintains a set of linkage tables which contain information on how
to interconnect the modules which make up the output file. A symbol table is
also maintained in memory. In order to be able to handle the linkage of
programs which are larger than the available memory, MLINK provides a virtual
memory file facility which can be used to provide buffering for the segments
in each module. The linkage tables and the symbol table are still maintained
in memory. Operation of the linker via virtual memory will certainly degrade
the speed performance of MLINK; however, it will enable you to link large
programs. It is beneficial if the VM file is on a RAMdisk. Switch -X
This switch is equivalent in operation to switch -E.
Switch -Y=<text>
This switch is used to specify the text for a 1F load module record. Text can
be continued onto as many additional lines as needed. A maximum of 255
characters may be entered. The '>' character terminates the text entry.
Switch -Z={y/N}
The normal operation of the linker is to suppress the generation of object
code for data regions which have been skipped over by the DS/DEFS pseudo-OP.
If you wish to generate byte zeroes (00H) for all such space in Command file generation:
The default origin of the REL stream will be the link origin (3000H for TRSDOS
6; 5200H for Model I/III operation). This default value may be permanently
patched at the link origin of the linker. You can also override the default
link origin at MLINK's execution by using the -L switch. All segments will be
loaded starting at this origin. You can alter the loading of the program,
data, and or common segments via the -P, -D, and -C switches. Once a switch is
in effect, all segments of the switched class will be origined relative to the
address entered. All unswitched segment classes continue to utilize the link
origin. The command file will be generated in the order of the modules loaded
unless you specify a different order via the -Q switch. The linker will NOT
advise you of any segments which overlap! Linker memory overhead free space requirements:
Each segment (code, data, common, absolute) requires 9 bytes plus the segment
length. Data and COMMON segments require an additional storage equal to the
segment length. Code, data, and common segments require no storage for the
segment length if the -V virtual memory switch has been specified. Overlay processing
MLINK supports the handling of programs which desire to use overlays. The
method is straightforward. A program may be partitioned into a root program
and one or more overlay programs. No address of an overlay is known to the
root program. The entry point of the overlay is its link origin established by
the linker. Proper entry is performed when the OVERLAY subroutine is called by
your root program. No address of an overlay is known to any other overlay. All
addresses of the root program are known to all overlays. The root program and
all overlays are generated in a single link session.
1) Search all libraries specified via a REQUEST assembler
instruction,
2) Fix all chain externals,
3) Fix all extern+offset,
4) Prepare MLINK for a new program chain. This resets the -Y
switch for the next chain (the -H switch is global). This
also establishes the transfer address (entry point) for all
overlays to be the next available LINK address after the
root. That LINK address will be used for the overlay's
entry and not a -P switched origin. It is therefore the
proper procedure to not use the -P, -D, and -C switches
if you want to use the overlay handling scheme of MLINK.
All modules loaded after an -O switch will be partitioned into a new chain.
PUBLIC symbols in one overlay chain of modules do NOT interfere with PUBLIC
symbols in other overlay chains; however, they must be distinct from the ROOT.
The terminating -E switch will fixup the last chain loaded and prepare for the
object file generation, if requested. Prior to its generation, the linker will
store the address of the first available byte following all modules into the
address of $MEMRY, if defined. The file specification of the overlays will
also be added to $OVLNAM if defined (this is part of the OVERLAY/REL
subroutine which has been provided).
1) Load reg_HL with any root program data,
2) Load reg_DE with a pointer to a File Control Block (This
is normally a 32-byte space under all systems except
TRSDOS 1.3),
3) Load reg_A with the desired overlay in ASCII
(i,e, LD A,'1'),
4) Invoke the OVERLAY handler via a CALL OVERLAY assembler
instruction.
Note that return is not made from this overlay handler routine unless an error
is detected in loading the requested overlay! However, the RETurn address to
OVERLAY is in register DE at the time control is passed to the overlay. You
therefore may find it useful to CALL a routine which CALLs OVERLAY. This is
illustrated in the following set of programs coded for operation under TRSDOS
6:
;TESTOVER/ASM
CSEG
BEGIN LD HL,START$
LD A,10 ;@DSPLY line handler
RST 40
LD A,'1'
CALL GETOVER
LD A,'2'
CALL GETOVER
LD A,'3'
CALL GETOVER
LD HL,FIN$
LD A,10 ;@DSPLY line handler
RST 40
RET
GETOVER LD DE,FCB
CALL OVERLAY## ;OVERLAY doesn't return unless error
OR 80H ;Set ABORT bit
LD C,A
LD A,26 ;@ERROR handler in DOS
RST 40
START$ DB 'This is the root executing',13
FIN$ DB 'End of processing',13
DSEG
FCB DS 32
END BEGIN
;TESTO1/ASM
CSEG
LD HL,MESS$
LD A,10
RST 40
RET
MESS$ DB 'This is overlay 1',13
END
;TESTO2/ASM
CSEG
LD HL,MESS$
LD A,10
RST 40
RET
MESS$ DB 'This is overlay 2',13
END
;TESTO3/ASM
CSEG
LD HL,MESS$
LD A,10
RST 40
RET
MESS$ DB 'This is overlay 3',13
END
The following MLINK session will create the root and overlay /CMD files as
DOOVER/CMD, DOOVER/OV1, DOOVER/OV2, and DOOVER/OV3 respectively:
mlink
testover:1,overlay:2
-o,testo1:1
-o,testo2:1
-o,testo3:1
-n=doover:1 -e
Error and Status messages:
Any of the following error messages may be displayed during processing of the
link session.
2nd COMMON larger /symbol/
The first reference to a common must be the largest.
Bad parameter(s)
The parameter of a switch was invalid for the switch.
Break detected
You depressed the <BREAK> key.
File not found
The referenced file was not found.
Filespec required
The switch required a filespec.
Internal Error
This error should not appear with properly assembled REL modules. If this
message does appear, save all of the REL modules and assembler source modules
loaded and contact MISOSYS.
Invalid command
The command character is not acceptable.
Invalid link item
Something is wrong in the REL bit stream.
Invalid switch
The switch entry is not supported.
Multiply defined symbol
A symbol has been defined at more than one address. When this occurs while a
module is being loaded, the message will be prefixed with the name of the
symbol. The -M switch appends an asterisk to the names of multiply defined
symbols. Symbols are generally in this category if two or more modules declare
them as PUBLIC, or if symbol names greater than seven characters in length are
truncated to seven characters by the assembler and thus are no longer unique.
Non-contiguous image file
File output generated with the -I switch must present a contiguous sequence of
load addresses. Thus, if you use the -P, -D, or -C switches, make sure that
the address ranges of each segment connect. Use the -R switch and start over.
Record 1F too long
The 1F record text exceeds 255 characters.
Symbol table overflow
There is no more buffer room. Use the virtual memory switch. If you already
are, you're probably out of luck. Try combining lots of little modules into
one big module. Read the section on the -V switch.
Unknown COMMON referenced
A named common has been referenced without it being defined. Most likely a REL
bit stream error.
Operating MLIB in interactive mode
MLIB functions in two different modes, interactive and batch. In the
interactive mode you can enter commands one at a time. MLIB will process the
command, and the results will be displayed when the command is completed. In
batch mode, MLIB will get its command input from an existing file containing
the sequence of commands. Batch mode is functional only under those operating
systems which support the "DO" command.
_______________________________________________________
| |
| MLIB (JCL,PAGE=nn) |
| MLIB * |
| |
| JCL - is used to specify BATCH mode. |
| |
| PAGE=nn - specifies page length for listings and can |
| range from 30-255 [make entry in decimal]. |
| If PAGE is omitted, it will default to 66. |
| |
| * - indicates a re-entry to MLIB (see text) |
| |
| Abbreviations: J=JCL, P=PAGE |
|_______________________________________________________|
Upon successful loading and execution of MLIB, a command menu similar to the
following is displayed:
_____ ________________________________________________
___|__ |TM |
| | | | MLIB 3.1L - Relocatable Object File Librarian |
| Ri|cl|in| (C) Copyright 1983 Riclin Computer Products |
| |__|__| |
|______| |
X Load library Save Library |
| Add module Module map |
| Purge module DOS Command |
| Replace module Clear buffer |
| Extract module eXit program |
| Insert before module |
| |
| Bytes used: 0, free: 29736 |
| |
|____________________________________________________________|
To execute a command, enter the first letter of the command (e.g. to select
"<L>oad library", enter the letter <L>). The only exception to
this is the "e<X>it program" command, which is selected by typing the
letter <X>. Alternatively, you may find it simpler to move the
blinking cursor until it is next to the desired command, and then depress
<ENTER> to execute that function. This is accomplished by using either
the <DOWN-ARROW> and <UP-ARROW> keys, or equivalently, the
<SPACE> and <BACKSPACE> keys. The blinking cursor will
reappear as a solid block next to the selected command, as a visual indication
of which command is executing.
Key entry Key function
------------------- -----------------------------------------
<LEFT-ARROW> non-destructive backspace
<RIGHT-ARROW> non-destructive forward space
<SHIFT-CLEAR> erase from cursor position to end of line
<SHIFT-LEFT-ARROW> restart from scratch
<SHIFT-RIGHT-ARROW> move cursor to end of line
<BREAK> cancel this command
<ENTER> invoke your entry.
If an error has occurred, MLIB will "beep" the console speaker if your machine
is so equipped (on a Model I/III computer, a short beep tone will be directed
to the cassette port which can be audible if you have an audio amplifier and
speaker hooked up). An error message will appear at the bottom of the screen,
and will remain there until you enter any keystroke, indicating that you have
acknowledged the error.
Re-entering MLIB
If you have exited MLIB accidently without saving the buffer to disk, or your
system has rebooted itself, or you were forced to reboot due to your system
crashing, MLIB may be re-entered by the command "MLIB *". All command line
parameter values will be retained as per the previous invocation of MLIB. In
nearly all cases your buffer will be intact. However, it is wise to
immediately request a detailed module map of what is now in the buffer. If
strange things appear in the map, then you have lost your data. If things look
normal, then you should save the buffer to disk right away. Prudent practice
dictates that you keep backups of your work, and if your system has hardware
problems, save the buffer to disk frequently to prevent loss of data. If a
reboot occurs or is necessary, don't forget to hold down the <ENTER>
key to prevent any AUTO command from being executed and possibly overwriting
the MLIB data.
MLIB commands
<A>dd module
This command adds a new module to the library in memory from a disk file. The
new module will be loaded following what is already in memory. Use of this
command is the primary method of building a new library or adding to an
existing one. It will abort on out of memory, symbol table overflow, or disk
error.
<C>lear buffer
This command resets all internal pointers, thus effectively destroying what is
currently in the memory buffer. In interactive mode, MLIB gives you a chance
to cancel this command if you decide not to clear the buffer.
<D>OS command
This allows you to enter any DOS library command. You will be prompted to
enter the command with the message, "Enter DOS command:".
<E>xtract module
This command extracts a single module from the library in memory and writes it
to disk as a stand-alone /REL or /IRL file. It will abort on module not found,
or disk error.
<I>nsert before module
This command inserts a new module from disk into the library in memory. Answer
the first prompt with the name of the module BEFORE which you wish to insert
the new module. This command will abort on module not found, disk error, out
of memory, or symbol table overflow.
<L>oad library
This command loads an existing library into memory from a disk file. It will
abort on disk error, out of memory, symbol table overflow, or data already in
memory.
<M>odule map
This command maps the attributes of the library which is currently in memory.
This listing can be in either detailed or summary format. When you request the
MODULE MAP command, you will be asked if you want a printer listing with the
question:
Listing to printer (Y,N) ?
You can print a module map, if desired, by responding <Y>. Printed
output is paginated at a page length of 66 lines unless changed by use of the
PAGE command line parameter. In either interactive or batch mode,
<BREAK> will cancel a printout at any time.
____________________________________________________________
| |
| Module name Module size Program size Data area size |
| DSKDRV 1417 996 76 |
| |
| Entries: $FLBUF $FLCNT $FLFCB $FLFLG $GTFCB $GTFLG |
| 0000" 0014" 0032" 0028" 0024" 0018" |
| $MEMRY DSKDRV OPEN |
| 0048" 000A' 033C' |
| |
| Externals: $BF $BL $CLSFL $ERR $IOERR $IOINI |
| $LUNTB $REC $UN |
| |
| Commons: |
| |
| Hit <ENTER> for next screen, Hit <BREAK> to exit |
|____________________________________________________________|
Module name
This is shown if it exists; otherwise "------" is displayed. If the module is
written with MRAS, the name is defined by use of the NAME pseudo-op or will
default to the REL file name.
Module size
This is the absolute length, in decimal, of the module, including all
segments, symbol definitions, etc. A stand-alone disk file containing the
module would have the same length plus one.
Program size
This is the length of the module's program segment, in decimal.
Data area size
This is the length of the module's data segment, in decimal.
Entries
Each entry point is defined by a symbol and its location within the module. A
module may have more than one entry point. MLINK entry symbols may be up to
seven characters in length. Locations are expressed in hexadecimal, relative
from the starting point of the segment in which the entry point is contained
(X'0000'). The entry point type is also displayed as follows:
{space} absolute segment
' program relative (code) segment
" data relative segment
! COMMON area
Externals
Any symbol which is not defined in the module is called an external symbol,
and is listed here. These are actually references to entry points defined in
other modules.
Commons
Any COMMON areas defined in the module are listed. The lengths of the COMMON
areas are also shown, in hexadecimal.
____________________________________________________________
| |
| RAN INT4 DSQRT DMOD DSIGN DABS DATAN2 |
| DATAN DLOG10 DCOS DSIN DBLEXP DEXP DLOG |
| DMIN1 DMAX1 DCOMP DBLDIV DBLFLR DBLPLY DBLUTL |
| DMLDV DSHR DBLCON MFM AMIN0 MIN0 AMAX0 |
| TANH SQRT MIN1 MAX1 MAX0 IFIX FLOAT |
| EXP DIM COSIN ATAN2 ATAN AMOD AMIN1 |
| AMAX1 AINT ABS ALOG10 ALOG MOD RIEXP |
| NEGF RREXP NEG NEG EXPB LOG2 POLY |
| FADD IIEXP FDIV STOP FMUL ADE FLR |
| FCP FLT CMPGTO IDIV SIGN RAT DAT |
| ISIGN IABS NEGATE XAR IDIM FAT2 IMUL |
| POKE UNPACK PSPLAC ICP FORMIO NORM SHIFT |
| RNDOVF ZAC IOINIT LUNTB IAT2 LODSTR SAF |
| |
| Hit
<P>urge module
This command purges a module from the library in memory. If the module has
multiple entry points, all will be deleted. In response to the prompt, enter a
module name. The module will then be purged, and the library in memory will be
compressed to recover freed space. This command will abort if the module is
not found in the symbol table.
<R>eplace module
This command replaces an existing module in memory with a new version from a
disk file. All aliases will be replaced or deleted. The new module may be
longer, shorter, or the same length as the old one - MLIB will compress,
overlay in place, or expand the library in memory to fit the new length. This
command will abort on module not found, out of memory, symbol table overflow,
or disk error.
<S>ave library
This command saves the entire library in memory to a disk file. MLIB will
prompt you, if the file already exists, as to whether you wish to overwrite or
not. This command will abort on memory empty, or disk error.
e<X>it program
This command exits MLIB and returns you to "DOS Ready". In interactive mode,
if there is data in the buffer which has not yet been saved to disk, you have
a chance to recover (i.e abort the eXit). If you choose to exit anyway, your
data will be lost, unless you re-enter MLIB immediately with the "MLIB *"
command, as explained in OPERATING MLIB IN INTERACTIVE MODE. If the data has
been saved, MLIB will exit immediately without a prompt.
Operating MLIB in batch mode
The command which executes MLIB in batch mode is as follows:
_______________________________________________________
| |
| MLIB (JCL,PAGE=nn) |
| |
| JCL - specifies BATCH mode. |
| |
| PAGE=nn - as shown earlier. |
| |
| Abbreviations: J=JCL, P=PAGE |
|_______________________________________________________|
In batch mode, MLIB will take its commands from a batch file, whose extension
is usually '/JCL'. Under some systems, the extension may be '/BLD'.
Batch command Comment
------------- --------------------------------
mlib (jcl) execute MLIB in batch mode
load load a library...
irl designate an "IRL"
funcs2 this one is FUNCS2/REL
add add a new module...
rel designate a "REL"
shelsort SHELSORT/REL
replace replace a module...
index module name is INDEX
rel designate a "REL"
index replace it with INDEX/REL
save save the new version of...
irl designate an "IRL"
funcs2 FUNCS2/REL
xit and exit to DOS
Error messages
MLIB will recover from all non-fatal errors; you will not lose your data.
Standard disk I/O errors may also occur, and MLIB will recover if at all
possible. Fatal errors result in an immediate return to DOS without warning.
In batch mode all errors become fatal, and will terminate execution.
Non-fatal errors:
Buffer empty
You cannot save the library, since memory is empty!
Buffer not empty
You cannot load a library if one is already in memory.
Invalid file format
You tried to read in a file which was not in the expected /REL format.
Module not found
A module name was not found; it was not in memory.
Out of memory
You cannot load a disk file because the file length would exceed available
memory. When replacing or inserting a module, there must be enough free memory
so that the new module can be read in before it is eventually relocated to its
correct position in the buffer. If you do run out of memory, it's time to
consider splitting the library into two smaller libraries.
Symbol table overflow
MLIB handles up to 200 individual modules; you have exceeded this limit.
Fatal errors:
Can't - buffer destroyed!
MLIB determined that part of the memory buffer was destroyed before MLIB was
re-entered with the "*" parameter.
Invalid option
An invalid command was given to MLIB while in batch mode.
Parameter error!
An invalid DOS command line parameter was entered. The only acceptable command
line parameters are "PAGE" which requires a decimal entry in the range 30
through 255, and "JCL", which can be either ON or OFF.
Unrecoverable error!
If a file has been read into memory which appears ON THE SURFACE to be a
/REL-format file, but really isn't, there is a high probability that an
unrecoverable error will occur during symbol table update. Invoking the SAID Editor
SAID is a full-screen text editor that can be used to edit assembler source,
C-language source, or other ASCII text files. When used under TRSDOS 6.x or
equivalent, SAID provides you with up to seven editing buffers, depending on
the availability of 32K memory banks, and the added capability of moving
blocks of text from one buffer to another. Before SAID is first used, please
install it into your system by running the SAIDINS installation program as
noted at the end of this chapter. SAID is easily invoked via:
____________________________________________________________
| |
| SAID [filespec] (parm1,parm2,...) |
| |
| SAID * Used to re-enter SAID immediately after |
| exiting so as to reclaim the text buffers. |
| |
| filespec The name of the file to edit. If filespec is |
| not found, SAID prompts to create it. |
| Command line filespec entry is optional. |
| |
| ASM Tabs default to 8. File extension defaults |
| to "/ASM". X'1A' stripped from end of file |
| on read and replaced on write. |
| |
| CCC Tabs default to 4. File extension defaults |
| to "/CCC". X'1A' stripped from end of file |
| on read and replaced on write. |
| |
| EXT=string Sets the default file extension. |
| |
| TAB=nn Set default tab width. |
| |
| Abbreviations: A=ASM, C=CCC, E=EXT, T=TAB |
| |
| Note: EXT parameter not usable under TRSDOS 1.3 and 2.3. |
| TRSDOS 1.3 users must enter ASM and CCC parms as |
| parm=0FFFF and TAB entry in hexadecimal, 0xx. |
|____________________________________________________________|
Unless altered by SAIDINS, SAID command functions are invoked with the
keyboard depressions as shown in the SAID menu. In the following text,
multiple key depressions are shown as connected sequences of keys within angle
brackets, i.e. <CLEAR><4> means simultaneously depress the
<CLEAR> key and the <4> key.
Editing Status
SAID can display a great deal of status concerning the text contained in the
editing buffer. You also can control the optional display of the SAID menu of
command keys. This information will look like the following:
--------+-------+-------+-------+-------+-------+-------+-------+-------+-------
Srch Repl Again All Rev Hex Quote Copy Move Cmd Print Exit
==1== ==2== ==3== ==4== ==5== ==6== ==7== ==8== ==9== ==0== ==:== ==-==
Ins Line Del Word Block Load Save Macro File Meta Pg Dn Pg Up
File:aaaaaaaaaaaaaa Len:bbbbb/ccccc Ln:ddddd Col:ee = x'ff' ggg% Banks: hhhhhhh
Srch:iiiiiiiiiiiiiiiiii Repl:jjjjjjjjjjjjjjjjjj Dir:kkk Cnt:lll
"Messages and prompts..." SAID Version 1.1
The top line will be a rule of dashes with a plus sign "+" denoting each TAB
stop as established by either the default tabbing for the file type [ASM=8,
CCC=4] or that set via the TAB parameter. Cursor Movement
Cursor movement relates to the re-positioning of the cursor on the screen.
"Up" movements invoked while the cursor is on the top line of the screen cause
the text to be scrolled downward. Conversely, "down" movements invoked while
the cursor is on the bottom text line will cause the text to be scrolled
upward.
Left one position <LEFT ARROW>
Right one position <RIGHT ARROW>
Up one line <UP ARROW>
Down one line <DOWN ARROW>
Beginning of next word <CLEAR><4>
Next Screen Page <CLEAR><->
Previous Screen Page <CLEAR><:>
Start of line <SHIFT><LEFT ARROW>
End of line <SHIFT><RIGHT ARROW>
Start of file <CLEAR><UP ARROW>
End of file <CLEAR><DOWN ARROW>
Insert a tab <CLEAR><RIGHT ARROW>
Modes
SAID operates in various modes. In normal operation, entered text overtypes
any text beneath the cursor. The cursor will appear as an underline unless it
is positioned over an underline character at which point the cursor will be
displayed as a full block (191D). When toggled into "insert" mode, all text to
the right of the cursor will be pushed down one character as each character is
entered. The cursor is also changed to a full block. Although a TAB character
occupies one position in the text buffer, it is expanded on the screen via
spacing to the next tab stop. In line insert mode, a line of spaces is
inserted into the text at the cursor position. A new line will automatically
be inserted when you attempt to type past the last position of the opened
line. Hex insertion mode can be invoked regardless of the state of insert
mode. The hex mode allows you to enter all 256 character values by the entry
of two hexadecimal digits per character. In quote insert mode, all cursor
movement functions are defeated and the character values used for the
functions are entered into the text when a cursor movement key is pressed.
Insert/overtype mode <CLEAR><1>
Line insert <CLEAR><2> - <Break> to cancel
Hex insert <CLEAR><SHIFT><6> - <Break> to cancel
Quote insert <CLEAR><SHIFT><7> - <Break> to cancel
Deletions
This section relates to the various operations of deleting text. When you
invoke a deletion, it is preserved by SAID and can be restored via the
Reverse-DELETE function; however, only the LAST deletion performed is saved.
Thus, if you delete a block via "delete-block", the character removed by the
DELETE key is lost after the "block" key causes the removal of the block since
the "block" delete is the last deletion. Fortunately, you only would have to
manually enter one character.
Delete character <CLEAR><3>.
Delete word <CLEAR><3> followed by <CLEAR><4>
or just <CLEAR><4> if in delete mode.
Delete line <CLEAR><3> followed by <CLEAR><2>
or just <CLEAR><2> if in delete mode.
Delete block Mark the block, position cursor inside,
then <CLEAR><3> followed by <CLEAR><5>
Delete to top <CLEAR><3> followed by <CLEAR><UP ARROW>
or just <CLEAR><UP ARROW> if in delete mode.
Delete to end <CLEAR><3> followed by <CLEAR><DOWN ARROW>
or just <CLEAR><DNARW> if in delete mode.
Delete all <CLEAR><3> followed by <CLEAR><SHIFT><4>.
Deletes entire context except macro.
Undelete [oops function] <CLEAR><SHIFT><5> followed by <CLEAR><3>
which is "reverse" followed by "delete".
Macro functions
SAID supports a macro key which can be soft programmed (or reprogrammed) by
you throughout the operation of SAID. This key can store up to 64 keystrokes.
Its use for capturing a series of key entries for repetitive entry will help
in speeding up your editing and minimize key entry. Note that invoking the
macro will cause it to repeat according to the repeat rate count set with the
Meta function. This repeat count is set to one when you store a series of
keystrokes for the macro key.
Invoke current macro <CLEAR><8>
Store a macro <CLEAR><6> followed by <CLEAR><8>; The Macro
will be saved until the next <CLEAR><8> or
until 64 characters are entered.
I/O functions
This section relates to the loading or saving of text as well as printing out
the text buffer or a portion of it. Note that when you are merging two or more
files into the text buffer, SAID will load the file at the cursor location -
be it the beginning of the text, the middle of the text, or the end of the
text. When you invoke "exit", SAID will prompt you to save any buffer which
contains text. Note that when you save a file or exit, you will be prompted
for the filespec. Respond via <ENTER> to use the current filespec
shown in the status line or enter a new filespec which will become the new
current one. SAID will abort a printing request if a <BREAK> is
detected.
Print a block Mark block, then <CLEAR><SHIFT><:>,
followed by <CLEAR><5> followed by <0-9>
Print a file [in memory] <CLEAR><SHIFT><:> followed by <CLEAR><9>
Load file at cursor position <CLEAR><6> followed by <CLEAR><9> then the
filespec in response to the prompt.
Save file under current name <CLEAR><7> followed by <CLEAR><9>
Save block Mark block, then <CLEAR><7> followed by
<CLEAR><5> followed by filespec, then <0-9>.
Exit <CLEAR><SHIFT><->
Change filespec <CLEAR><9> followed by the filespec.
Block functions
SAID allows you to designate up to ten distinctly labeled blocks. These are
numbered from 0-9. You can have more than one block designated with the same
number; however, in block copy or block move operations, the first such
numbered block found in the text when searched from the beginning of the file
will be used for the copy or move operation. Blocks are marked by indicating a
BLOCK START and a BLOCK END (the end marker must appear in the text after the
start marker).
Block start <CLEAR><5> followed by <0-9>
Block end <CLEAR><5> followed by <CLEAR><DOWN ARROW>
or <CLEAR><5> followed by <E>.
Copy block Mark block, position to destination, then
<CLEAR><SHIFT><8> followed by <0-9>. Note
that this command duplicates the contents
of the block at the new position. The
marked block is retained in its marked
position.
Move block Mark block, position to destination, then
<CLEAR><SHIFT><9> followed by <0-9>. Note
that this command deletes the marked block
after inserting the block text into the
designated position.
Unmark all blocks <CLEAR><SHIFT><5> followed by <CLEAR><5>.
Use before saving assembler source.
Search and replace
This section relates to the facility for finding character strings in the text
and optionally replacing them with another string. The replacement string may
be null. If any character in the search string is in uppercase then the search
will be case sensitive (i.e. "A" and "a" are distinct), otherwise the search
will be case insensitive (i.e. "A" and "a" are considered to be the same
character). The search string may contain a wildcard character or characters
which match all character values (the wildcard character is specified during
the installation via SAIDINS). The replacement string may also contain a
wildcard character or characters which indicates that the character in that
position in the search string will be re-used in the replacement string. Both
the search and replacement strings may contain hexadecimal values via entry of
a per cent "%" character followed by two hexadecimal digits. "Again" finds the
next matching string or replaces the next matching string. "All" invokes the
search or replace on all matching strings. Note that the meta command provides
an option to force a query before replace which is also installable with
SAIDINS.
Search <CLEAR><SHIFT><1> followed by the string.
Reverse search <CLEAR><SHIFT><5> followed by <CLEAR><SHIFT><1>
followed by the search string.
Replace Invoke a SEARCH, then <CLEAR><SHIFT><2>
followed by the replacement string.
Again <CLEAR><SHIFT><3>
All <CLEAR><SHIFT><4>
Miscellaneous
Invoke a DOS command -- <CLEAR><SPACE>
This allows you to enter any DOS command that is acceptable at DOS Ready with
the exception of any command which alters HIGH$.
Invoke a Meta command -- <CLEAR><0> followed
by [C,E,G,H,M,O,R,T,7,UP,DN]
This gives you access to an additional set of infrequently accessed commands.
The meta command letter determines the function invoked.
C Calculator
E External memory [TRSDOS 6.x version only]
S swap memory bank and full context
C copy a block from an external memory bank
G Go to the start of a line via its line number
H Toggle the help display
M Set macro repeat count
O Set SAID options
A set ASM mode in current buffer
C set CCC mode in current buffer
T set default extension in current buffer
R Replace options: query before replace
T Set tabs position (i.e. every nth column)
7 Strip bit 7 off all text in buffer
<UP ARROW> Uppercase next word
<DOWN ARROW> Lowercase next word
Calculator
SAID contains a built-in reverse polish notation calculator which supports the
following three types of numbers:
xxxxB - Binary (i.e. 101101)
xxxxD - Decimal (default, i.e. 45)
xxxxH - Hexadecimal (i.e. 2d)
The following functions are supported:
* Multiplication
/ Division
+ Addition
- Subtraction (negation is not supported)
& Logical AND
| Logical OR
^ Logical XOR
. Used to denote the previous result
If you wish to output the answer in any base other than decimal then follow
the '=' with a 'B' or an 'H' to specify binary or hexadecimal. Entering a
period will cause the last result to be substituted. Note the following sample
calculation which multiplies 22 base 16 by 1111 base 2, then adds 2 base 10
and outputs the result in decimal:
22h 1111b * 2 +
To output the same result in binary, specify ". =b".
Installing SAID [running SAIDINS]
SAID should be installed in your system by invoking the command,
SAIDINS filespec
where "filespec" should be SAID/CMD - the name of the screen editor - unless
you renamed SAID/CMD to some other name. SAID is supplied to support all of
the SAID functions mapped to the keyboard, with the exceptions of functions
34, 35, and 36. This mapping can be tailored to your specifications during the
installation of SAID while SAIDINS/CMD is running. This installation program
must be used first to establish certain DOS interfacing needed before SAID can
be used. The following function codes are used during the installation of
SAID. They designate the function numbers corresponding to the thirty-six
separate command functions in SAID.
1 Cursor left 19 Meta
2 Cursor right 20 Previous Page
3 Cursor up 21 Next Page
4 Cursor down 22 Find
5 Beginning of line 23 Replace
6 End of line 24 Again
7 Top of file 25 All
8 End of file 26 Unmark
9 Insert a tab 27 Hex
10 Insert mode toggle 28 Quote
11 Line 29 Copy block
12 Delete 30 Move block
13 Word 31 DOS command
14 Block 32 Print
15 Load 33 Exit
16 Save 34 Delete previous character
17 Macro 35 Swap buffer with external buffer # 1
18 File 36 Swap buffer with external buffer # 2
The TRSDOS 6.x version of SAID uses the DOS keyboard driver and makes use of
the type-ahead supported by the DOS. The Model I/III version of SAID contains
a built in keyboard driver which supports type-ahead as well as a complete
ASCII keyboard. The installation program can be used to override this built-in
keyboard driver. For LDOS users who are using the DOS KI/DVR, you must either
override the SAID driver or not use the LDOS KI/DVR (meaning that type-ahead
must be off). The Model I/III keyboard driver uses various key combinations to
produce the extra characters not available on the TRS-80 keyboard. These are
as follows:
<CLEAR>, plus: <CLEAR><SHIFT>, plus:
<,> [ (left bracket) <,> { (left brace)
</> \ (reverse slash) </> | (vertical bar)
<.> ] (right bracket) <.> } (right brace)
<;> ^ (carat) <;> (tilde)
<ENTER> _ (underline) <ENTER> (delete)
<SHIFT><DOWN ARROW> (control - use with A-Z)
Invoking XREF
The XREF utility is used to generate a cross reference listing of symbols used
in your source code of a single assembly stream. Its syntax is:
_____________________________________________________________
| |
| XREF filespec/REF {(LEN=val,PAGE=val,LINES=val,EQU,LIMIT)} |
| |
| filespec is the specification of the reference data |
| file generated by the -XR switch of MRAS. If |
| the file extension is omitted, "REF" is used. |
| |
| LEN is the length of your print line (the default |
| value is 80). |
| |
| PAGE is the maximum number of lines per page (the |
| default is 66 for Mod I, 67 for Mod III). |
| |
| LINES is the number of lines to print on a page (the |
| default is 56 for Mod I, 57 for Mod III). |
| |
| EQU is used to generate a file of EQUates instead |
| of the cross reference listing. |
| |
| LIMIT is used to limit the file of EQUates to those |
| symbols containing a special character. |
| |
| Note: the format of "value" is PARM=ddd or PARM=X'hhhh'. |
| |
| PAGE is not supported under TRSDOS 6.x |
| |
| There are no parameter abbreviations. |
|_____________________________________________________________|
The XREF/CMD utility generates a symbolic cross-reference listing which
includes a sorted list of all defined labels, the file of origin of the
definition, the line number of the definition, the value of the definition,
and the line numbers of all statements referencing the label. XREF will also
identify the filename of the file containing the references. XREF will not
identify unresolved labels. Therefore, make sure that either all labels are
resolved during the assembly that generates the XREF data file, or you do not
need the line numbers of those unresolved references appearing in the cross
reference listing. LEN
This parameter controls the printed line length during the XREF listing. If
omitted, a value of 80 is assumed to deal with 80-column line printers. If you
are using a wide-carriage printer (typically 132 columns), then XREF can use
the entire print line by specifying the parameter as:
XREF (LEN=132)
PAGE
This parameter controls the page size. A value of 66 lines per page (67 on the
Model III due to its line counter starting from 1 instead of 0) is used. If
your paper is shorter or longer, you can respecify the page length from the
command line. For instance:
XREF filespec (PAGE=51,LINES=41)
will set the page length to 51 lines per page and initialize to print 41
lines.
LINES
This parameter controls the quantity of lines printed on a page before a form
feed is generated. LINES defaults to a value of 56.
EQU
This parameter controls the generation of the EQUate file. If specified, then
the cross reference listing is suppressed and a source file of symbols equated
to their value is generated. The filespec used to write the EQUate file will
be constructed using the filename and drive specification of the "/REF" file.
A file extension of "/EQU" will be used. Symbols defined by the "DEFL"
pseudo-OP will be maintained as DEFL's in the EQUate file.
LIMIT
This parameter controls what symbols are written to the EQUate file. If
entered in addition to the "EQU" parameter, then the EQUate file will be
limited to those symbols that contain at least one special character (a
character other than A-Z, 0-9).
Cross-Reference Listing
Three informative messages will be displayed prior to generating the listing.
"Building symbols declared" will be displayed as XREF creates a table of all
symbols declared. The message, "Sorting symbol table" will be displayed as the
symbols are sorted. A second pass through the REF data file will be made while
the message, "Building symbols referenced" is displayed. This pass is used to
create a second table of all references to symbols. Origin
The filename where the symbol was declared. The ORIGIN will list either the
source filename or the filename of the "*GET"/"*SEARCH" directive.
Symbolic Label
This column contains the defined symbol name. If the symbol was defined by a
"DEFL" pseudo-OP, a plus sign, "+", will precede the symbol name.
Value
This column contains the value of the symbol as determined during the assembly
process. If the symbol shows a DEFL definition, the value will be the first
defined value.
Line#
This column lists the line number of the statement defining the symbol.
Usage
This column contains the filename of the file containing a reference to the
label. It will be the filename of the *GET/*SEARCH filespec.
Line# of References
This field will contain the line number of all source statements which
reference the symbol. All of the references listed on a print line will be
contained in the file identified under the usage column. Whenever the Usage
file changes, it will cause a new line to be generated in the listing.
Statistics
The quantity of symbols defined is listed along with the quantity of
references associated with those definitions.
Tips for programming relocatable modules
Make a module's /REL filename the same as its program NAME and its main ENTRY
point. This will help you build libraries in an organized way. Microsoft compatible 'REL' format
All Z80 assemblers work in a similar fashion, in that they convert a file
containing SOURCE CODE, written in Z80 assembly language mnemonics, to OBJECT
CODE in some binary format. In ABSOLUTE assemblers, this binary data is a
faithful representation of the actual machine language (ones and zeros) that
the Z80 will execute when you want your program to run. This object code can
only load and execute at a FIXED address in the Z80's memory space. On the
other hand, a RELOCATABLE assembler, such as MRAS, will generate object code
which can be relocated to any address in the Z80's 64K memory space before the
program is to be executed. MRAS and MLINK support a Microsoft compatible
relocation format.
0100 00100 ORG 0100H
4470 00110 @DATE EQU 4470H
402D 00120 @EXIT EQU 402DH
4467 00130 @DSPLY EQU 4467H
000D 00140 CR EQU 0DH
0100 211401 00150 START: LD HL,BUFFER
0103 CD7044 00160 CALL @DATE
0106 3E0D 00170 LD A,CR
0108 321C01 00180 LD (BUFFER+8),A
010B 211401 00190 LD HL,BUFFER
010E CD6744 00200 CALL @DSPLY
0111 C32D40 00210 JP @EXIT
0114 00220 BUFFER: DS 9
0100 00230 END START
@DATE 4470 @DSPLY 4467 @EXIT 402D
BUFFER 0114 CR 000D START 0100
The program has been reassembled below at a new origin, 0200H. Some of the
addresses for the above labels have changed, while some remain the same:
0200 00100 ORG 0200H
4470 00110 @DATE EQU 4470H
402D 00120 @EXIT EQU 402DH
4467 00130 @DSPLY EQU 4467H
000D 00140 CR EQU 0DH
0200 211402 00150 START: LD HL,BUFFER
0203 CD7044 00160 CALL @DATE
0206 3E0D 00170 LD A,CR
0208 321C02 00180 LD (BUFFER+8),A
020B 211402 00190 LD HL,BUFFER
020E CD6744 00200 CALL @DSPLY
0211 C32D40 00210 JP @EXIT
0214 00220 BUFFER: DS 9
0200 00230 END START
@DATE 4470 @DSPLY 4467 @EXIT 402D
BUFFER 0214 CR 000D START 0200
To be specific, START and BUFFER have changed, while the others are unchanged.
Both START and BUFFER have been relocated! START, instead of being at 0100H is
now at 0200H, and BUFFER has moved from 0114H to 0214H. This offset of 0100H
is due to the changed origin, 0100H versus 0200H. START and BUFFER are
therefore internally relocatable values, while @DATE, for example, will always
be 4470H, and is thus known as an absolute value.
4470 @DATE EQU 4470H
402D @EXIT EQU 402DH
4467 @DSPLY EQU 4467H
000D CR EQU 0DH
0000' 21 0014' START: LD HL,BUFFER
0003' CD 4470 CALL @DATE
0006' 3E 0D LD A,CR
0008' 32 001C' LD (BUFFER+8),A
000B' 21 0014' LD HL,BUFFER
000E' CD 4467 CALL @DSPLY
0011' C3 402D JP @EXIT
0014' BUFFER: DS 9
END START
@DATE 4470 @DSPLY 4467 @EXIT 402D
BUFFER 0014' CR 000D START 0000'
All of the internal program addresses have been assembled as if the program
had an origin of 0000H, and are noted with a following single-quote ('). This
is relocation at work. The binary output of this assembly (a /REL file) cannot
be executed by the Z80 until you choose an origin for the program; this is
done by the MISOSYS linker, MLINK), and can be ANY address in the Z80 memory
space. MLINK will determine, from the origin you have selected, where START
and BUFFER really will be when the program is run. If you choose 0100H as the
origin, then START will be located at 0100H, and BUFFER at 0114H. Other
origins will produce similar results; START and BUFFER will be at different
addresses, but the offset between them (0014H) will always be the same.
;Module 1
ENTRY LABEL1 ;this is an entry point
LABEL1:
{code follows}
END ;end of module 1
;Module 2
EXTRN LABEL1 ;this is an EXTERNAL declaration
;could also be EXT.
CALL LABEL1 ;and this is a reference to the
;external
END ;end of module 2
The relocatable format also allows you to do other things. In many
applications, program code and data areas must be separated. This most often
occurs when code must be placed in ROM, such as the BASIC interpreter in a
TRS-80. However, the data areas cannot be in ROM; they must be in writeable
memory (RAM), and thus must be separated from the code areas. This can be
accomplished by use of the CSEG and DSEG commands to the MRAS assembler. A
CSEG pseudo-operation signals the start of a code area, while a DSEG indicates
the start of a data area. Code and data SEGMENTS may be intermixed in a
program source file, and the assembler will automatically keep them separate
by the use of two distinct program or location counters, one for each segment.
When you link the program with MLINK, you may tell the linker at what address
to place the code, and also where to place the data. Thus the two segments are
separated. The above example is shown below using this technique:
4470 @DATE EQU 4470H
402D @EXIT EQU 402DH
4467 @DSPLY EQU 4467H
000D CR EQU 0DH
0000' CSEG ;code starts here
0000' 21 0000" START: LD HL,BUFFER
0003' CD 4470 CALL @DATE
0006' 3E 0D LD A,CR
0008' 32 0008" LD (BUFFER+8),A
000B' 21 0000" LD HL,BUFFER
000E' CD 4467 CALL @DSPLY
0011' C3 402D JP @EXIT
DSEG ;data starts here
0000" BUFFER: DS 9
END START
@DATE 4470 @DSPLY 4467 @EXIT 402D
BUFFER 0000" CR 000D START 0000'
Notice how the label BUFFER is now located at 0000H, but in the data segment,
as indicated by the double-quote (") following the address. Am MLINK session
could then be as follows with user entries in BOLDFACE:
DOS Ready
MLINK
MLINK - Ver 1.0a Copyright 1985 MISOSYS, Inc., All rights reserved
?-p=100
?-d=1000
?test
27937 Free space
P <0100-0113 0014> D <1000-1008 0009>
*test-n-e
DOS Ready
The -p command to the linker established the program (or code) segment origin,
while the -d command did the same for the data segment. After loading TEST/REL
with the next command, the linker then tells us where the two segments are
located and how long they are. The final command writes out an executable
command file (/CMD). If we were to disassemble TEST/CMD, we would find that
START is located at 0100H and BUFFER at 1000H. Thus the program is separated
into ROM and RAM sections.
NAME ('TEST')
4470 @DATE EQU 4470H
402D @EXIT EQU 402DH
4467 @DSPLY EQU 4467H
000D CR EQU 0DH
CSEG ;code starts here
ENTRY START
EXT MESSAGE
0000' 21 0000" START: LD HL,BUFFER
0003' CD 4470 CALL @DATE
0006' 3E 0D LD A,CR
0008' 32 0008" LD (BUFFER+8),A
000B' 21 0000" LD HL,BUFFER
000E' 11 0000* LD DE,MESSAGE
0011' 01 0009 LD BC,BUFFLEN
0014' ED B0 LDIR
0016' 21 0000* LD HL,MESSAGE
0019' CD 4467 CALL @DSPLY
001C' C3 402D JP @EXIT
DSEG ;data starts here
ENTRY BUFFER
0000" BUFFER: DS 9
0009 BUFFLEN EQU $-BUFFER
END START
@DATE 4470 @DSPLY 4467 @EXIT 402D
BUFFER 0000" BUFFLEN 0009 CR 000D
MESSAGE 0017* START 0000'
Notice how the external label, MESSAGE, is defined in the symbol table; the
value 0017H represents the relative location of the LAST reference to MESSAGE
in the assembled code, and the trailing asterisk (*) denotes an external
symbol both in this table and in the assembled code listing.
(1) Absolute [0] or relocatable [1] item [1 bit]. If absolute, column (2)
shows the value in hex [8 bits].
(2) Relocation type [0 = special link item; 1, 2, or 3 = segment relative]
[2 bits]. See column (8).
(3) Special link item control field in decimal [4 bits]. See column (8).
(4) "A-field" address type, same as column (2) [2 bits].
(5) "A-field" value, displayed as high/low, but reversed in file [16 bits].
(6) "B-field" length [3 bits].
(7) "B-field" symbol in ASCII [8 bits each character].
(8) Description of the object file record as decoded.
(1) (2) (3) (4) (5) (6) (7) (8)
--- --- --- --- ------ -- ------- -----------------------------------
1 0 2 4 TEST program name
1 0 0 5 START entry symbol for library search
1 0 0 6 BUFFER entry symbol for library search
1 0 10 0 00 09 define data area size
1 0 13 1 00 1F define program size
1 0 11 1 00 00 set loading location counter (code)
0 21 absolute (1st byte in code segment)
1 2 00 00 data relative (ref. to BUFFER)
0 CD absolute
0 70 absolute
0 44 absolute
0 3E absolute
0 0D absolute
0 32 absolute
1 2 00 08 data relative (ref. to BUFFER+8)
0 21 absolute
1 2 00 00 data relative (ref. to BUFFER)
0 11 absolute (ref. to MESSAGE follows)
0 00 absolute (this plus next byte are
0 00 absolute end of external chain)
0 01 absolute
0 09 absolute
0 00 absolute
0 ED absolute
0 B0 absolute
0 21 absolute (ref. to MESSAGE follows)
1 1 00 0F program relative (link in chain)
0 CD absolute
0 67 absolute
0 44 absolute
0 C3 absolute
0 2D absolute
0 40 absolute
1 0 11 2 00 00 set loading location counter (data)
1 0 11 2 00 09 set loading location counter (data)
1 0 7 2 00 00 6 BUFFER define entry point (data)
1 0 6 1 00 17 7 MESSAGE chain external (head of list)
1 0 7 1 00 00 5 START define entry point (code)
1 0 14 1 00 00 end program (force to next byte)
1 0 15 end file marker
Relocation Format of /REL files
The REL file is an encoded bit-stream containing relocatable object code
information. It follows the format documented by Microsoft for the M-80
assembler and L-80 linker; however, only 16-bit externals are supported and
the linker currently does not support chain address. The following text
documents the bit stream supported by MLINK.
01 - indicates a code relative value follows. The next 16 bits are loaded
after being offset by the code segment origin, THEN recycle to 1).
10 - indicates a data relative value follows. The next 16 bits are loaded
after being offset by the data segment origin, THEN recycle to 1).
11 - indicates a common relative value follows. The next 16 bits are
loaded after being offset by the selected common segment origin,
THEN recycle to 1).
00 - Indicates a Special Link item. The SL item consists of the following
four bits which are interpreted as one of 16 different items
described below; an optional VALUE field which consists of a 2-bit
address type [00 = absolute, 01 = code relative, 10 = data relative,
11 = common relative] and a 16-bit address; and an optional NAME
field that consists of a 3-bit name length followed by the name in
8-bit bytes. SLs 0000-0100 use only a NAME field; SLs 0101-1000 use
both a VALUE field and a NAME field; SLs 1001-1110 use only a VALUE
field; SL 1111 has neither a NAME nor a VALUE field. Unless otherwise
specified, at the conclusion of processing a special link item,
processing recycles to 1). The Special Link items are as follows:
0000 - indicates an entry symbol. This is used by the linker only
when searching a library to see if the module is needed to
satisfy an undefined extern.
0001 - Select Common Block. Used to specify the NAMEd Common Block
for subsequent common relative references.
0010 - Module name. This is the name of the module. The first one
encountered is saved by MLINK for use in generating the
optional HEADER record of the /CMD file.
0011 - Request Library Search. The library designated by the NAME
field will be searched to resolve undefined externals prior
to any object code generation. An REL will be first assumed.
If one is not found, an IRL will then be assumed.
0100 - This item is not supported by MLINK.
0101 - Define Common Size. This is used by MLINK to establish the
size of the common block designated by the NAME field.
0110 - Chain External. The VALUE field contains a pointer to the head
of a chain which ends with an absolute zero. Each 16-bit
element of the chain will be replaced with the value of the
external symbol described in the NAME field.
0111 - Define Entry Point. The VALUE field specifies the value of the
symbol described by the NAME field.
1000 - This item is not supported by MLINK.
1001 - External plus Offset. This specifies that the VALUE field must
be added to the following two bytes in the current segment
after all chain externals have been processed.
1010 - Define Data Size. The VALUE field is used by MLINK to
establish the size of the data segment of the current module.
1011 - Set Location Counter. The location counter is set to the value
identified by the VALUE field.
1100 - This item is not supported by MLINK.
1101 - Define Code Size. The VALUE field is used by MLINK to
establish the size of the code segment of the current module.
1110 - End of Module. The VALUE field defines the transfer address
for the module if other than absolute zero. This item
denotes the end of the module. The bit stream is also
advanced to a byte boundary. Recycle to 1) if loading a
module from other than a library search.
1111 - End of File. This is used to indicate the end of the file.
It is used when searching libraries or when loading modules
to detect the end of the file.