Listing of file='LPTEST.MAC;02' on disk='vmedia/sound_light_pen-sector.ccvf'
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; ; LIGHT-PEN TEST ROUTINE ; ; VALUES ON ENTRY ARE IRRELEVANT ; ; RETURNS: ; DE = 0 MEANS NO LIGHT ; DE = -1 MEANS LIGHT PRESENT ; NOTE: DE IS USED FOR COMPATIBILITY WITH BASIC ; ; DESTROYS: ; ACC, AND OF COURSE DE ; ENTRY LPTEST LPTEST: MVI D,10 TS10: MVI E,0FFH TS20: MVI A,14 ;SELECT PORT 'A' ON AY-3-8910 OUT 30H IN 30H ;READ IT ANI 01 ;TEST PEN FOR LIGHT PRESENT JNZ TS25 ;NO, LOOP NOP ;WAIT A LITTLE NOP MVI A,14 ;CHECK PEN AGAIN ('DEBOUNCE') OUT 30H IN 30H ANI 01 JZ TS30 TS25: DCR E JNZ TS20 DCR D JNZ TS10 RET ;RETURN ZERO FOR NOT LIT TS30: MVI D,0FFH MOV E,D RET ;RETURN -1 FOR LIT END