2 ; IRQ handling (ATARI 5200 version)
5 .export initirq, doneirq
8 .include "atari5200.inc"
10 ; ------------------------------------------------------------------------
23 ; ------------------------------------------------------------------------
33 ; ------------------------------------------------------------------------
34 ; Set deferred vertical blank interrupt
35 ; logic copied from Atari computer ROM
39 sta WSYNC ; waste 20 CPU cycles
40 @1: dex ; to allow VBLANK to happen
41 bne @1 ; if this is line "7C"
46 ; ------------------------------------------------------------------------
52 jsr callirq ; Call the functions
53 jmp IRQInd ; Jump to the saved IRQ vector
55 ; ------------------------------------------------------------------------