Hello Ferdinand,
BB>> One problem is, a single timer tick is too long. What else can I use
BB>> as a timer so that the speed is the same on all machines?
 FG> Why not try the vertical retrace? It should have the same speed on
 FG> most machines...
     Thanx Ferdinand, I was able to steal some code from Denis Boyles :-)
;----------------------------------------
;WaitRetrace - waits for vertical retrace
;----------------------------------------
CGAPort     EQU 03DAh                  ;port address for CGA status register
WaitRetrace PROC
    mov     DX,CGAPort                 ;DX = CGAPort to read status from
WR0:                                   ;flush out current retrace if any
    in      AL,DX                      ;read status into AL from port
    test    AL,1000b                   ;test bit 3 (8) for retrace?
    jnz     WR0                        ;loop while its on to flush retrace
WR1:                                   ;wait for start of new retrace
    in      AL,DX
    test    AL,1000b
    jz      WR1                        ;keep looping until retrace occurs
    ret
WaitRetrace ENDP
;----------------------------------------
Kind regards, Barry
--- Terminate 4.00/Pro
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