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December 23, 2019 21:09
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| ; TO PLAY A TONE FROM APPLESOFT... | |
| ; POKE 769,DURATION : POKE 771,FREQUENCY : CALL 768 | |
| 0300- A0 64 LDY #$FF ; LOAD DURATION | |
| 0302- A9 01 LDA #$FF ; LOAD FREQUENCY | |
| 0304- 85 FA STA $FA ; VALUE AT $FA WILL SLIDE DOWN, CREATING THE VIOLIN EFFECT | |
| 0306- AE 03 03 LDX $0303 ; INITIALIZE TONE COUNTER WITH FREQUENCY | |
| 0309- E4 FA CPX $FA ; COMPARE WITH SLIDING VALUE | |
| 030B- D0 03 BNE $0310 ; SKIP SPEAKER CLICK IF NOT EQUAL | |
| 030D- AD 30 C0 LDA $C030 ; CLICK SPEAKER | |
| 0310- CA DEX ; DECREMENT TONE COUNTER | |
| 0311- D0 F6 BNE $0309 ; LOOP UNTIL TONE COUNTER IS ZERO | |
| 0313- AD 30 C0 LDA $C030 ; CLICK SPEAKER AGAIN | |
| 0316- 88 DEY ; DECREASE DURATION COUNTER | |
| 0317- F0 07 BEQ $0320 ; BRANCH TO END IF DURATION COUNTER REACHES ZERO | |
| 0319- C6 FA DEC $FA ; ELSE DECREMENT THE SLIDING VALUE | |
| 031B- D0 E9 BNE $0306 ; LOOP UNTIL THE SLIDING VALUE IS ZERO | |
| 031D- 4C 02 03 JMP $0302 ; RESET SLIDING VALUE IF IT'S EQUAL TO ZERO | |
| 0320- 60 RTS ; DONE |
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DATA 160,100,169,1,133,250,174,3,3,228,250,208,3,173,48,192,202,208,246,173,48,192,136,240,7,198,250,208,233,76,2,3,96
Just to make life easier for anyone else who finds it. Not too bad. In fact I made a little "tune" over at https://gist.github.com/TedThompson/f24afa324949bee61114ac22e1bf6df2