$CPU 8086          ' make compatible with XT systems
$LIB ALL OFF       ' turn off all PowerBASIC libraries
$ERROR ALL OFF     ' turn off all PowerBASIC error checking
$OPTIMIZE SIZE     ' optimize for smaller code
 $COMPILE UNIT     ' compile to a UNIT (.PBU)
'$COMPILE EXE      ' compile to a UNIT (.PBU)

DEFINT A-Z         ' Required for all numeric functions, forces PB to not
                   ' include floating point in UNIT (makes it smaller)
'/*------------------------------------------------------------------*/
$CODE SEG "MLIB12"
'/*------------------------------------------------------------------*/
%FLAGS = 0
%AX = 1
%BX = 2
%CX = 3
%DX = 4
%SI = 5
%DI = 6
%BP = 7
%DS = 8
%ES = 9

FUNCTION VFADE() PUBLIC AS STRING
' IF LEN( Target$ ) = 0 THEN
    Target$ = STRING$( 765, 0 )
    REG %AX, &H1017
    REG %BX, 0
    REG %CX, 255
    REG %ES, STRSEG( Target$ )
    REG %DX, STRPTR( Target$ )
    CALL INTERRUPT &H10
' END IF
  FOR J% = 1 TO 32
    CALL FadeDAC( -4, Target$ )
  NEXT J%
  FUNCTION = Target$
END FUNCTION

SUB VSHOW(BYVAL Target$) PUBLIC
  IF LEN( Target$ ) = 0 THEN
    EXIT SUB
  END IF
  FOR J% = 1 TO 32
    CALL FadeDAC( 4, Target$ )
  NEXT J%
END SUB

SUB FadeDAC(BYVAL Inc%, BYVAL Target$) PRIVATE
  LOCAL Buff$, N%, K%
  Buff$ = STRING$( 765, 0 )
  REG %AX, &H1017
  REG %BX, 0
  REG %CX, 255
  REG %ES, STRSEG( Buff$ )
  REG %DX, STRPTR( Buff$ )
  CALL INTERRUPT &H10
  FOR J% = 1 TO LEN( Buff$ )
    N% = ASC( MID$( Buff$, J%, 1 )) + Inc%
    IF N% < 0 THEN N% = 0
    K% = ASC( MID$( Target$, J%, 1 ))
    IF N% > K% THEN N% = K%
    MID$( Buff$, J%, 1 ) = CHR$( N% )
  NEXT J%
  REG %AX, &H1012
  REG %BX, 0
  REG %CX, 255
  REG %ES, STRSEG( Buff$ )
  REG %DX, STRPTR( Buff$ )
  CALL INTERRUPT &H10
END SUB
'/*------------------------------------------------------------------
'   $INCLUDE "C:\CODE\MLIB\MLIB.INC"
'   CLS
'   SHELL "D C:\"
'   A$ = VFADE
'   INPUT Z
'   VSHOW A$
'   INPUT Z