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35 lines
603 B
35 lines
603 B
; program to test user buzzer/speaker on Z80 MBC clock board
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; by Andrew Lynch, 6 Jul 2021
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org $0100
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LD HL,$7FFF ; INITIALIZE OUTER LOOP
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LD DE,$0001 ; DECREMENT VALUE
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START:
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LD A,%00000100
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OUT ($70),A ; TURN ON SPEAKER
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LD B,$80 ; HOLD SPEAKER ON FOR 128 COUNTS
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LOOP1: DJNZ LOOP1
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LD A,%00000000
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OUT ($70),A ; TURN OFF SPEAKER
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LD B,$80 ; HOLD SPEAKER OFF FOR 128 COUNTS
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LOOP2: DJNZ LOOP2
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SBC HL,DE ; REDUCE OUTER LOOP BY 1
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JR NZ,START ; LOOP 32768 TIMES, ABOUT 15 SECONDS
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LD A,%00000011
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OUT ($70),A ; TURN ON BOTH USER LEDS
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; HALT ; HALT & TURN ON HALT LED
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RET
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end
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