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Routines |
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Plays a single cycle of a square wave: the speaker is turned on for the duration and then off for the same duration.
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| PlaySquareWave | BF74 | LD A,$10 | A=10 (bit 4 turns the speaker on). | |||||
| BF76 | OUT ($FE),A | Write A to port FE (border black, speaker on). | ||||||
| BF78 | LD A,B | Stash the duration in A. | ||||||
| PlaySquareWave_Loop | BF79 | DJNZ PlaySquareWave_Loop | Decrease duration by one and loop back to PlaySquareWave_Loop until it is zero. | |||||
| BF7B | LD B,A | Restore the duration to B. | ||||||
| BF7C | XOR A | A=00. | ||||||
| BF7D | OUT ($FE),A | Write A to port FE (border black, speaker off). | ||||||
| BF7F | LD A,B | Stash the duration in A. | ||||||
| Silence_Loop | BF80 | DJNZ Silence_Loop | Decrease duration by one and loop back to Silence_Loop until it is zero. | |||||
| BF82 | LD B,A | Restore the duration to B. | ||||||
| BF83 | RET | Return. | ||||||
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View the equivalent code in;
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