THE HT1080Z EMULATOR

HT1080Z - VideoGenie-I/System-80/HT-1080Z emulator

(C) 2004-2005 Attila Grósz (gyros AT freemail DOT hu)
http://ht.homeserver.hu/


What's a HT-1080Z?

The HT-1080Z was the second official school computer in Hungary. Initial versions were unaltered VideoGenie-1 computers relabeled and mounted with an on-board Yamaha/General Instruments AY-3-8910 sound chip. Later revisions had accented characters and modified ROM contents. This Yamaha chip is the same one that appeared in other famous computer models, such as the Amstrad and the Atari ST.

The current version of the emulator supports the unaltered HT1080Z which is basically a VideoGenie with the Yamaha sound chip, along with the BASIC ROM extension and the second series of HT1080Z's with some of the extended characters of the Hungarian alphabet.

The VideoGenie (as marketed in Europe) and the System-80 (as marketed in New Zealand and Australia) were in turn slightly modified clones of the popular TRS-80 Model 1 Level II.

What's this thing I've just downloaded?

Emulator, that imitates the behaviour of a piece of computer hardware on another platform, in this specific case thus an 8-bit VideoGenie-1 is emulated on the Windows platform that is at the moment 32-bit.

Although a very good TRS-80 emulator exists that is in a great deal capable of emulating a VideoGenie as well, it has no specific support for this series and is also shareware.

HT1080Z is in turn freeware, and may be distributed freely if unaltered, and the copyright notice is retained. As a consequence, the author take no responsibilities whatsoever for any damage caused by this emulator.
In short: use it at your own risk!

HT1080Z also exploits the possibilities of a graphical user interface with features such as drag'n'drop, intuitive menus etc.

New releases of the emulator will be published on the following page: http://ht.homeserver.hu/

Features of the HT1080Z emulator

Missing features of the emulator

Usage

Running

To be able to run this program, minimum Windows 95 is needed. No install is necessary, just copy the contents of the ZIP package to a new folder and click on the executable called HT1080Z.

The simplest way to get programs started is with drag'n'drop or via the File->Autostart menu option. When drag'n'dropping a DSK file, keeping the Ctrl key down will reboot the emulated machine.

Command line options

General format:

HT1080Z.EXE [/a] [/d] [/g] [/h] [/i filename] [/m] [/r] [/w] [filename]

For now, only a few command line switches are supported:

/a : suppress autostart of CAS and CMD images
/d : enable double scan of screen lines
/g : Lowe LE15 High Resolution Graphic Adapter emulation
/h : disables sound at startup (by default it's on)
/i : insert diskimage on startup into drive:0
/m : specify HT model (1, 2 or 3)
/r : specify RAM size (16 or 48)
/w : run the emulator with the maximum speed possible

Monitor

The program has a simple built-in monitor/disassembler. By pressing ESC[-APE] can this be entered. On pressing this button again, one can return to the emulated machine. Further keyboard shortcuts:

F1 : Disassembly list from the actual value of the IP. On top of the page, the current state of the CPU is shown.
F2 : Memory map of the emulated machine
F4 : Set breakpoint at actual position
F5 : Switch to emulator screen when in monitor
F7 : Run until here (if possible within a given amount of cycles)
ENTER : Step one assembly instruction
PAGE UP : One page up in the list
PAGE DOWN : One page down in the list
UP-ARROW : One row upwards in the list
DOWN-ARROW: One row downwards in the list

Drive

Full drive and WD1771 disk controller emulation is available. Image support is restricted to DSK images (also known as JV1 and JV3) for now.

Any DOS that is supported on a TRS-80 Model I should work well in the emulator, among others: TRSDOS and NewDOS.

The /i command line option can be used to attach a boot disk image on startup, so that the emulator will boot up in DOS mode. Holding the BREAK key (TAB in the emulator) down on startup however will enforce booting into normal BASIC mode.

If a disk image has been altered, the user will be prompted upon detaching it, or exiting the emulator whether the changes should be saved or not.

At the moment disk drive support is not very robust, so do not use ot for important stuff. The emulator is somewhat fussy about the disk images too: it will only accept perfectly aligned 89.600, 102.400 and 204.800 bytes long files as valid JV1 or 98.304, 111.104 and 213.504 bytes long files as valid JV3 images (35, 40 and 80 sectors respectively).

Tape

This was the most widespread and thus most important peripheral of the VideGenie as it was built-in to the computer case.

Two major formats exist for tape emulation: CAS and WAV. Latter is at the moment write-only, the former is read and writeable.

WAV

This format can be used if one would like to transfer a program to the real machine. The result can be then played back via the sound output of the PC to a tape and reloaded on the real machine.
For creating such WAV, one has to first choose 'Create WAV' from the Tape menu, press PLAY/RECORD by selecting the appropriate menu point from the Tape menu and issuing the necessary commands in the emulated machine (for example: CSAVE"NAME"). The saving process is done realtime (=slow) but the process can be accelerated by pressing ALT+F3 that gives full CPU power to the emulator on your machine. It is important that once the save command has finished the tape must be stopped (via the Tape menu, by ticking PLAY/RECORD off) and the WAV should be closed (very important!).
Just like the TRS-80 Model I Level 2, the VideoGenie-1 also used a 500 baud tape recording frequency.

CAS

Quicker and more efficient format, widespread in the TRS-80 world. It is a literal byte-exact representation of what is written to a real tape on a real TRS-80/VideoGenie-1/System-80/HT1080Z.Saving/loading of CAS files is done via ROM traps and hence it is not supporting custom loaders, but in return it is much quicker. Most load and save operations finish in a snap. BASIC programs can be saved with the CSAVE"N" command, in this case a pop-up window will appear where you must fill in the name and location of the desired CAS image.Saving a given memory location in CAS format is also possible via the file menu. Here you must fill in the begin and the end of the memory area that is about to be saved along with the start address which defaults to 0066h which is the NMI entry point (RESET).

BASIC extension

The emulator comes with support for the BASIC ROM extension and the machine code monitor. To enter the extended mode, one should type

>SYSTEM
*? /12288

into the emulator. For a full list of possibilities, see the relevant PDF documentation available on Terry Stewart's System 80 page.

Thanks

Links

Terry Stewart's System 80 resource site: http://www.webweavers.co.nz/system-80/
Hungarian VideoGenie/System-80/HT-1080Z tribute website: http://ht.homeserver.hu/
Ira Goldklang's TRS-80 website: http://www.trs-80.com/

Changelog

v1.5

v1.4

v1.3

v1.2

v1.1

v1.0

Without version nr.

(Attila Grósz)