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Routines |
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Used by the routine at WaitForKey.
Turns A and B into a duration and a pitch and hands them to the ROM beeper. The key click uses A equal to 1E. Action 0 of the bytecode jumps straight to the same ROM routine, whose address is the operand of the jump below.
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| Beep | 6AC4 | AND A | Duration A is the low byte of HL, and B is the pitch. | |||||||
| 6AC5 | LD L,A | |||||||||
| 6AC6 | LD A,B | |||||||||
| 6AC7 | LD D,$00 | The high byte of the duration, and D, start at zero. | ||||||||
| 6AC9 | LD H,D | |||||||||
| 6ACA | ADD A,A | Shift the pitch two places, keeping the overflow in D. | ||||||||
| 6ACB | ADD A,A | |||||||||
| 6ACC | RL D | |||||||||
| 6ACE | LD E,A | Save that pitch. | ||||||||
| 6ACF | PUSH DE | |||||||||
| 6AD0 | CALL $30A9 | Call HL_HLxDE to scale the duration by the pitch. | ||||||||
| 6AD3 | POP DE | Restore the pitch for the beeper from the stack. | ||||||||
| 6AD4 | JP $03B5 | Jump to BEEPER. | ||||||||
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