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194 lines
8.5 KiB
Markdown
194 lines
8.5 KiB
Markdown
# KSynth
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Beginnings of a dual tone synthesizer for the Apple II
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All the code is in this README, since it's small enough to copy and paste into an emulator for now.
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The synth code itself
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##Two Tone Generator##
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```
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0300- A5 FD LDA $FD ; load second oscillator value into $FE
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0302- 85 FE STA $FE ;
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0304- A9 FF LDA #$FF ; load duration multiplier into $FC
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0306- 85 FC STA $FC ;
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0308- A4 FA LDY $FA ; load duration into Y
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030A- A6 FB LDX $FB ; load oscillator into X
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030C- CA DEX ; start countdown first oscillator, X
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030D- EA NOP ; wait...
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030E- EA NOP ;
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030F- D0 05 BNE $0316 ; if X = 0, click. otherwise, skip
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0311- 2C 30 C0 BIT $C030 ; click
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0314- A6 FB LDX $FB ; reset X to beginning of countdown
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0316- C6 FE DEC $FE ; countdown second oscillator, $FE
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0318- EA NOP ; wait...
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0319- EA NOP ;
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031A- D0 07 BNE $0323 ; if $FE = 0, click. otherwise, skip
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031C- 2C 30 C0 BIT $C030 ; click
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031F- A5 FD LDA $FD ; reset $FE to beginning of countdown
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0321- 85 FE STA $FE ;
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0323- 88 DEY ; countdown duration
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0324- D0 E6 BNE $030C ; if duration hasn't expired, return and count down oscillators
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0326- A4 FA LDY $FA ; if duration has expired, reset duration
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0328- C6 FC DEC $FC ; decrement duration multiplier
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032A- D0 E0 BNE $030C ; if multiplier hasn't expired, return and count down oscillators
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032C- 60 RTS ; all done
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300: A5 FD 85 FE A9 FF 85 FC A4 FA A6 FB CA EA EA D0 05 8D 30 C0 A6 FB C6 FE EA EA D0 07 8D 30 C0 A5 FD 85 FE 88 D0 E6 A4 FA C6 FC D0 E0 60
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```
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##Player##
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```
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0330- A9 00 LDA #$00 ; start at zero
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0332- AA TAX ; X = 0; LOOP
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0333- BD 00 10 LDA $1000,X ; load note duration
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0336- F0 31 BEQ $0369 ; if note is 0 duration, end the song
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0338- 85 FA STA $FA ; store duration at $FA
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033A- E8 INX ; increment to note value
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033B- BD 00 10 LDA $1000,X ; load note value
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033E- 85 FB STA $FB ; store note value at $FB
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0340- 85 FD STA $FD ; store note value at $FD
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0342- C9 FF CMP #$FF ; if note value is FF, rest
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0344- D0 06 BNE $034C ; skip over if !=FF
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0346- 8D 1E 03 STA $031E ; change the $C030 click to $$FF30
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0349- 8D 13 03 STA $0313 ; change the $C030 click to $$FF30
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034C- C6 FD DEC $FD ; decrement $FD for That Karateka Sound™
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034E- 8A TXA ; put current note address in Accumulator
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034F- 85 FF STA $FF ; store that in $FF
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0351- 20 00 03 JSR $0300 ; play the actual note
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0354- AD 13 03 LDA $0313 ; did we mess with the C030 click?
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0357- C9 FF CMP #$FF ; if it's FF, we did. change it back.
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0359- D0 08 BNE $0363 ; skip if !=FF
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035B- A9 C0 LDA #$C0 ; set click points back to $c030
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035D- 8D 1E 03 STA $031E ;
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0360- 8D 13 03 STA $0313 ;
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0363- E6 FF INC $FF ; increment to next note address
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0365- A5 FF LDA $FF ; load Accumulator with next note address
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0367- D0 C9 BNE $0332 ; branch to LOOP
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0369- 60 RTS ;
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330: A9 00 AA BD 00 10 F0 31 85 FA E8 BD 00 10 85 FB 85 FD C9 FF D0 06 8D 1E 03 8D 13 03 C6 FD 8A 85 FF 20 00 03 AD 13 03 C9 FF D0 08 A9 C0 8D 1E 03 8D 13 03 E6 FF A5 FF D0 C9 60
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```
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##Creating Music##
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Music is stored in the following format, beginning (by default) at $1000.
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Starting address = A ($1000)
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A+0 = duration
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_e.g. FF = 1.63 seconds_
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A+1 = note
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_e.g. 59 = 440Hz A_
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per chart at [https://www.seventhstring.com/resources/notefrequencies.html]
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NOTE | C | C# | D | Eb | E | F | F# | G | G# | A | Bb | B |
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|-----| ------ | ------ | ------ | ------ | ------ | ------ | ------ | ------ | ------ | ------ | ------ | ------ |
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FREQ | | | | 155.6 | 164.8 | 174.6 | 185.0 | 196.0 | 207.7 | 220.0 | 233.1 | 246.9
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BYTE | | | | FC | EF | E1 | D5 | C9 | BD | B3 | A9 | 9F
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FREQ | 261.6 | 277.2 | 293.7 | 311.1 | 329.6 | 349.2 | 370.0 | 392.0 | 415.3 | 440.0 | 466.2 | 493.9
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BYTE | 96 | 8E | 86 | 7E | 77 | 71 | 6A | 64 | 5E | 59 | 54 | 4F
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FREQ | 523.3 | 554.4 | 587.3 | 622.3 | 659.3 | 698.5 | 740.0 | 784.0 | 830.6 | 880.0 | 932.3 | 987.8
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BYTE | 4B | 47 | 43 | 3F | 3C | 38 | 35 | 32 | 2F | 2D | 2A | 27
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FREQ | 1047 | 1109 | 1175 | 1245 | 1319 | 1397 | 1480 | 1568 | 1661 | 1760 | 1865 | 1976
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BYTE | 25 | 23 | 21 | 1F | 1E | 1C | 1A | 19 | 17 | 16 | 15 | 13
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##Bb scale:##
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```
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1000: 20 A9 20 96 20 86 20 7E 20 71 20 64 20 59 20 54 20 59 20 64 20 71 20 7E 20 86 20 96 FF A9 FF FF 10 A9 10 86 10 71 10 54 10 71 10 86 FF A9 00
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```
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##Karateka victory:##
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```
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1000: 10 a8 20 FF 8 c7 5 FF 10 a8 15 FF 25 7e 20 FF 10 63 08 FF 80 63 00 00
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```
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and, of course, the requisite
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##Daisy Bell (Bicycle Built For Two)##
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```
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1000: 30 71 30 86 30 A9 30 e1 10 C9 10 B3 10 A9 20 C9 10 A9 60 e1 30 96 30 71 30 86 30 A9 10 C9 10 B3 10 A9 20 96 10 86 40 96 10 FF 10 86 10 77 10 86
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1030: 10 96 20 71 10 86 10 96 40 A9 10 96 20 86 10 A9 20 C9 10 A9 10 C9 40 e1 10 E1 20 A9 10 86 10 96 20 FF 20 A9 10 86 10 96 10 FF 5 86 5 77 10 71 10 86 10 A9 20 96 10 e1 40 A9 00 00
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```
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##MIDI Translation##
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Using the above table as a starting point, a MIDI lookup table can be created. MIDI addresses up to 127 notes, from a C three octaves below Bass Clef, up to a G 9 octaves above. [http://www.midikits.net/midi_analyser/midi_note_numbers_for_octaves.htm]
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440hz A is note 69 in MIDI, so byte 69 (0x45) of the KSYNTH lookup table.
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By shifting 12 bytes up or down (one octave), a song's range can be easily be changed to fit in KSYNTH's limited range.
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```
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C C# D D# E F F# G G# A A# B
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0 00 00 00 00 00 00 00 00 00 00 00 00
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1 00 00 00 00 00 00 00 00 00 00 00 00
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2 00 00 00 00 00 00 00 00 00 00 00 00
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3 00 00 00 00 00 00 00 00 00 00 00 00
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4 00 00 00 FC EF E1 D5 C9 BD B3 A9 9F
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5 96 8E 86 7E 77 71 6A 64 5E 59 54 4F
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6 4B 47 43 3F 3C 38 35 32 2F 2D 2A 27
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7 25 23 21 1F 1E 1C 1A 19 17 16 15 13
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8 00 00 00 00 00 00 00 00 00 00 00 00
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9 00 00 00 00 00 00 00 00
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1133: FC EF E1 D5 C9 BD B3 A9 9F 96 8E 86 7E 77 71 6A 64 5E 59 54 4F 4B 47 43 3F 3C 38 35 32 2F 2D 2A 27 25 23 21 1F 1E 1C 1A 19 17 16 15 13
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```
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##MIDI-like Player##
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_assumes song src at $1000_
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_assumes lookup table src at $1100_
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```
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0330- A9 00 LDA #$00 ; start at zero
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0332- AA TAX ; X = 0; LOOP
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0333- BD 00 10 LDA $1000,X ; load note duration
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0336- F0 31 BEQ $0369 ; if note is 0 duration, end the song
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0338- 85 FA STA $FA ; store duration at $FA
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033A- E8 INX ; increment pointer to note value
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033B- BD 00 10 LDA $1000,X ; load note MIDI-style value
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TAY ; lookup note loop value from lookup table
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LDA $1100,Y ;
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033E- 85 FB STA $FB ; store note value at $FB
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0340- 85 FD STA $FD ; store note value at $FD
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0342- C9 FF CMP #$FF ; if note value is FF, rest
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0344- D0 06 BNE $034C ; skip over if !=FF
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0346- 8D 1E 03 STA $031E ; change the $C030 click to BIT $FF30
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0349- 8D 13 03 STA $0313 ; change the $C030 click to BIT $FF30
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034C- C6 FD DEC $FD ; decrement $FD for That Karateka Sound™
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034E- 8A TXA ; put current note pointer in Accumulator
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034F- 85 FF STA $FF ; store that in $FF
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0351- 20 00 03 JSR $0300 ; play the actual note
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0354- AD 13 03 LDA $0313 ; did we mess with the C030 click?
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0357- C9 FF CMP #$FF ; if it's FF, we did. change it back.
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0359- D0 08 BNE $0363 ; skip if !=FF
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035B- A9 C0 LDA #$C0 ; set click points back to $c030
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035D- 8D 1E 03 STA $031E ;
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0360- 8D 13 03 STA $0313 ;
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0363- E6 FF INC $FF ; increment to next note address
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0365- A5 FF LDA $FF ; load Accumulator with next note address
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0367- D0 C9 BNE $0332 ; branch to LOOP
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0369- 60 RTS ;
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330: A9 00 AA BD 00 10 F0 31 85 FA E8 BD 00 10 A8 B9 00 11 85 FB 85 FD C9 FF D0 06 8D 1E 03 8D 13 03 C6 FD 8A 85 FF 20 00 03 AD 13 03 C9 FF D0 08 A9 C0 8D 1E 03 8D 13 03 E6 FF A5 FF D0 C9 60
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This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License. [http://creativecommons.org/licenses/by-sa/3.0/us/]
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