mirror of
https://github.com/sehugg/8bitworkshop.git
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429 lines
12 KiB
Plaintext
429 lines
12 KiB
Plaintext
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processor 6502
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include "vcs.h"
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include "macro.h"
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include "xmacro.h"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;
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; This example drives the VCS audio DAC directly to generate
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; 4-voice music. Unfortunately, the CPU is 100% utilized so
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; we can't display anything.
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;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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seg.u Variables
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org $80
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; 16-bit wavetable offset
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Cycle0Lo byte
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Cycle1Lo byte
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Cycle2Lo byte
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Cycle3Lo byte
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Cycle0Hi byte
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Cycle1Hi byte
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Cycle2Hi byte
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Cycle3Hi byte
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; 16-bit wavetable delta
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Delta0Lo byte
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Delta1Lo byte
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Delta2Lo byte
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Delta3Lo byte
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Delta0Hi byte
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Delta1Hi byte
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Delta2Hi byte
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Delta3Hi byte
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; 8-bit wavetable offset (volume)
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WaveOfs0 byte
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WaveOfs1 byte
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WaveOfs2 byte
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WaveOfs3 byte
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SongPtr word ; ptr to next song byte
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DurationTimer byte ; duration until next song byte
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CurChannel byte ; next channel to write
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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seg Code
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org $f000
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; Macro that decrements volume for a channel
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MAC DECVOLUME
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lda WaveOfs0+{1}
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sec
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beq .ChannelOff
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sbc #$20
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.ChannelOff
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sta WaveOfs0+{1}
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ENDM
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Start
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CLEAN_START
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lda #$FF
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sta COLUPF
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sta ENABL
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jsr ResetTrack
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NextFrame
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DECVOLUME 0
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jsr Pulse
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jsr PlayFrame
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DECVOLUME 1
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jsr Pulse
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jsr PlayFrame
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DECVOLUME 2
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jsr Pulse
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jsr PlayFrame
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DECVOLUME 3
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jsr Pulse
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jsr PlayFrame
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jmp NextFrame
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; Play a frame's worth of samples
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PlayFrame
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TIMER_SETUP 212
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TimerLoop1
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jsr NextSamples
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lda INTIM
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cmp #3
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bcs TimerLoop1
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Macro that mixes two software voices
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; and sets the volume for one TIA audio channel.
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; Usage: NEXTSAMPLEPAIR {audiochannel} {voice1} {voice2}
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MAC NEXTSAMPLEPAIR
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; Get first channel phase, put in X
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lda Cycle0Lo+{2}
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clc
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adc Delta0Lo+{2}
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sta Cycle0Lo+{2}
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lda Cycle0Hi+{2}
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adc Delta0Hi+{2}
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sta Cycle0Hi+{2}
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and #$1F
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clc
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adc WaveOfs0+{2}
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tax
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; Get second channel phase, put in Y
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lda Cycle0Lo+{3}
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clc
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adc Delta0Lo+{3}
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sta Cycle0Lo+{3}
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lda Cycle0Hi+{3}
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adc Delta0Hi+{3}
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sta Cycle0Hi+{3}
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and #$1F
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clc
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adc WaveOfs0+{3}
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tay
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; Lookup wavetable entry and sum
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lda Wavetable,y
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clc
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adc Wavetable,x
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; Divide by 2 and store to volume register
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lsr
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; sta COLUBK
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sta AUDV0+{1}
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ENDM
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NextSamples
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NEXTSAMPLEPAIR 0,0,1 ; mix voices 0 and 1
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NEXTSAMPLEPAIR 1,2,3 ; mix voices 2 and 3
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rts
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; Play a note
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; X = channel (0,1)
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; Y = note index (0-63)
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PlayNote
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tya
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asl
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tay
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lda NoteDeltas,y
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sta Delta0Lo,x
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lda NoteDeltas+1,y
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sta Delta0Hi,x
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lda #$e0
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sta WaveOfs0,x
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rts
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; Reset to start of song
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ResetTrack
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lda #<NOTEZ
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sta SongPtr+0
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lda #>NOTEZ
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sta SongPtr+1
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rts
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; Called every frame
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; Decrement next-note timer, fetch next note
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Pulse
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lda DurationTimer
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beq NextData
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dec DurationTimer
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rts
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; Timer ran out, so fetch next note
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NextData
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jsr NextSamples
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ldx #0
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lda (SongPtr,x) ; get next song byte
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bmi LoadDuration
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; < $80, so play next note
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ldx CurChannel ; load next channel #
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tay
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jsr PlayNote ; play note
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inx
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txa
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and #3
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sta CurChannel ; inc to next channel
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jmp IncDataPtr
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; >= $80 so load next duration
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LoadDuration
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cmp #$ff
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beq ResetTrack ; $ff = end of song
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and #$7f
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asl
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sta DurationTimer ; store duration * 2
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IncDataPtr
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; increment song pointer
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inc SongPtr
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bne NoIncHi
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inc SongPtr+1
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NoIncHi
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rts
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; 32-byte wavetable
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align $100
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Wavetable
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hex 00000000 00000000 00000000 00000000
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hex 00000000 00000000 00000000 00000000
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hex 04040404 04040404 04040404 04040404
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hex 04040404 04040404 00000000 00000000
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hex 06060606 06060606 06060606 06060606
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hex 06060606 06060606 00000000 00000000
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hex 08080808 08080808 08080808 08080808
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hex 08080808 08080808 00000000 00000000
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hex 0b0b0b0b 0b0b0b0b 0b0b0b0b 0b0b0b0b
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hex 0b0b0b0b 0b0b0b0b 0b0b0b0b 00000000
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hex 0d0d0d0d 0d0d0d0d 0d0d0d0d 0d0d0d0d
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hex 0d0d0d0d 0d0d0d0d 00000000 00000000
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hex 0f0f0f0f 0f0f0f0f 0f0f0f0f 0f0f0f0f
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hex 0f0f0f0f 00000000 00000000 00000000
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hex 0f0f0f0f 0f0f0f0f 0f0f0f0f 0f0f0f0f
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hex 00000000 00000000 00000000 00000000
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; hex 00010203 04050607 08090a0b 0c0d0e0f
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; hex 0f0e0d0c 0b0a0908 07060504 03020100
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; Table of note periods
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NoteDeltas
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word 17, 18, 19, 20, 22, 23, 24, 26, 27, 29, 31, 32,
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word 34, 36, 39, 41, 43, 46, 49, 51, 54, 58, 61, 65,
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word 69, 73, 77, 82, 86, 92, 97, 103, 109, 115, 122, 130,
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word 137, 145, 154, 163, 173, 183, 194, 206, 218, 231, 245, 259,
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word 274, 291, 308, 326, 346, 366, 388, 411, 436, 462, 489, 518,
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word 549, 582, 616, 653, 692, 733, 776, 823, 871, 923, 978, 1036,
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word 1098, 1163, 1232, 1306, 1383, 1466, 1553, 1645, 1743, 1847, 1956, 2073,
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word 2196, 2327, 2465, 2611, 2767, 2931, 3106, 3290, 3486, 3693, 3913, 4145,
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word 4392, 4653, 4930, 5223, 5533, 5862, 6211, 6580, 6972, 7386, 7825, 8291,
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word 8784, 9306, 9859, 10446, 11067, 11725, 12422, 13161, 13943, 14772, 15651, 16582,
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word 17568, 18612, 19719, 20891, 22134, 23450, 24844, 26322,
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NOTEZ
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hex 358a378a333f8a303c943e328a3a2e94
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hex 35298a372b8a33278a30249432268a2e
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hex 2294291d8a2b1f8a271b8a2418941a26
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hex 8a18248a17238a1622a83a35322e9429
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hex 26228a2a8a2b1b8a338a221f278a2b8a
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hex 332216942b2725228a338a2014942724
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hex 941f138a3f37338a383527228a39368a
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hex 3a37168a3f37338a353822278a3a378a
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hex 168a3e35328a38352622943f33371b94
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hex 1f22279427221f942926228a2a8a2b1b
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hex 8a338a1f22278a2b8a332216942b2725
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hex 228a338a2014942427941f13943c3330
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hex 1e8a3a332e8a39332d1d8a3c308a3f33
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hex 1d248a378a1d8a358a3f3327218a3c30
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hex 8a353826229422169424189429261a8a
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hex 2a8a2b1b8a338a27221f8a2b8a331622
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hex 942b2725228a338a201494272494131f
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hex 8a3f33378a383527228a39368a373a16
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hex 8a3f37338a383527228a3a378a168a3e
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hex 35328a38352026943f37331b9427221f
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hex 942b2722943f338a358a37271b8a3f33
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hex 8a352b22278a378a25198a3f338a352b
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hex 27228a3f338a3724188a3f338a352c27
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hex 248a378a23178a3f338a352c27238a3f
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hex 338a3a3722168a3f37338a38352b278a
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hex 3a378a168a3e32358a35382622943f33
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hex 371b9422169424189429261a8a2a8a2b
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hex 1b8a338a27221f8a2b8a332216942b25
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hex 22278a338a2014942724941f138a3f37
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hex 338a353827228a39368a3a37168a3f37
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hex 338a383527228a3a378a168a3e35328a
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hex 353820229437333f1b9427221f942722
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hex 1f942926228a2a8a2b1b8a338a221f27
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hex 8a2b8a332216942b2725228a338a2014
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hex 942724941f13943c33301e8a3a332e8a
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hex 2d33391d8a3c308a3f3327248a378a1d
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hex 8a358a333f27248a3c308a3835262294
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hex 22169424189429261a8a2a8a2b1b8a33
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hex 8a22271f8a2b8a332216942b2725228a
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hex 338a2014942427941f138a3f37338a38
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hex 3527228a36398a3a37168a3f37338a38
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hex 3527228a373a8a168a3e35328a383522
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hex 209433373f1b9427221f9422272b943f
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hex 338a358a37271b8a3f338a352b27228a
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hex 378a25198a3f338a352b22278a3f338a
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hex 3724188a333f8a352c27248a378a2317
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hex 8a3f338a352c27238a3f338a3a372216
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hex 8a3f37338a38352b278a373a8a168a3e
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hex 35328a383522269433373f2794221694
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hex 1b0f8a372b338a382c358a39362d8a3a
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hex 372e0f943c37302b8a3a2e378a168a37
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hex 332b8a2c38352b8a39362d8a3a372e1b
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hex 943c3730278a2e373a8a168a378a3327
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hex 2b228a2e8a30148a328a332c27248a35
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hex 8a37208a358a332c27238a358a2e1f8a
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hex 378a382b27228a3a8a3c168a3a8a3722
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hex 2b278a388a3a372e1b943c30372b8a3a
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hex 372e8a168a37332b8a382c35228a3936
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hex 2d8a3a372e1b943c37302b8a2e373a8a
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hex 1f8a3a8a3c1e8a3d8a3e3a351d8a3e35
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hex 3a8a2229268a3e33398a1d8a3c8a3933
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hex 29278a358a3a322926942014941f138a
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hex 372b338a38352c1d8a39362d8a2e3a37
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hex 1b943c3730228a3a372e8a168a332b37
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hex 8a38352c2b8a39362d8a3a372e1b9430
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hex 373c2b8a3a2e378a168a378a332b2722
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hex 8a2e8a30148a328a332c27248a358a37
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hex 208a358a33232c278a358a331f942b22
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hex 27941b8a2e8a2d2b27258a2e8a332c27
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hex 2494302c27248a338a21242a278a308a
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hex 332a27248a308a2e2b27228a338a372b
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hex 22278a3a8a2b27228a378a332b27228a
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hex 2e8a302d1d2794332d241d94372c2622
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hex 8a352c8a26228a332b8a271b94221694
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hex 1f138a3f378a381d118a398a3a372e1b
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hex 943c3037228a3a372e8a168a37332b8a
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hex 382c352b8a39362d8a3a372e1b943c37
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hex 302b8a2e373a8a168a378a332b27228a
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hex 2e8a30148a328a332c27248a358a3720
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hex 8a358a3323272c8a358a2e1f8a378a38
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hex 272b228a3a8a3c168a3a8a372b27228a
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hex 388a3a372e1b943c30372b8a3a372e8a
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hex 168a37332b8a382c352b8a39362d8a3a
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hex 372e1b943c3730228a2e373a8a1f8a3a
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hex 8a3c1e8a3d8a3e3a351d8a3e353a8a29
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hex 26228a3e33398a1d8a3c8a393327248a
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hex 358a3a322926942014941f138a372b33
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hex 8a38352c118a39362d8a2e3a371b943c
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hex 37302b8a3a372e8a168a332b378a3835
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hex 2c2b8a39362d8a3a372e1b94303c372b
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hex 8a372e3a8a168a378a332b27228a2e8a
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hex 30148a328a3327242c8a358a37208a35
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hex 8a332c27238a358a331f942b2722941b
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hex 8a2e8a2d2b27258a2e8a332c27249430
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hex 2c20278a338a2a2724218a308a332a27
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hex 248a308a2e2b22278a338a372b27228a
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hex 3a8a2b27228a378a332b22278a2e8a30
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hex 2d271d94332d241d94372c26228a352c
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hex 8a26228a332b8a271b942216941b0f94
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hex 298a2a8a2b1b8a338a271f228a2b8a33
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hex 2216942b2725228a338a201494272494
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hex 1f138a3f37338a383527228a39368a3a
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hex 37168a3f37338a383527228a3a378a16
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hex 8a3e35328a38352220943f37331b9427
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hex 221f94221f27942926228a2a8a2b1b8a
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hex 338a27221f8a2b8a332216942b272225
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hex 8a338a2014942724941f1394333c301e
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hex 8a3a332e8a39332d1d8a3c308a3f3327
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hex 248a378a1d8a358a3f3327248a3c308a
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hex 353826229422169424189429261a8a2a
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hex 8a2b1b8a338a1f22278a2b8a33221694
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hex 2b2725228a338a2014942427941f138a
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hex 3f37338a383527228a39368a373a168a
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hex 3f33378a353827228a3a378a168a3e35
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hex 328a38352622943f37331b9427221f94
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hex 222b27943f338a358a37271b8a3f338a
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hex 352b27228a378a25198a333f8a352722
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hex 2b8a3f338a3724188a3f338a352c2724
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hex 8a378a23178a3f338a3523272c8a3f33
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hex 8a3a3716228a33373f8a38352b278a3a
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hex 378a168a32353e8a38352622943f3733
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hex 27942216943f37331ba8383c148a3b8a
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hex 3c382427941b943f3c382c94383d1994
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hex 312c29258a308a31208a338a352c2529
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hex 943835118a378a38352c299418943c38
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hex 352494353a3d16942e25298a2d8a2e1d
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hex 8a308a3129258a3a8a352519943a2529
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hex 8a358a22168a3a8a3523179433241894
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hex 24272c94381d942c292494371f8a3b8a
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hex 3e26292b8a8a238a8a3e2b29268a3f8a
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hex 3c2b2724a83d22272b941b943c38148a
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hex 3b8a383c2c27941b943f3c382c943d38
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hex 1994312c25298a308a31208a338a352c
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hex 2925943835118a378a38352c24941894
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hex 353c382c943d3a3516942e29258a2d8a
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hex 2e1d8a308a3129258a3a8a352519943a
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hex 29258a358a16228a3a8a352317943324
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hex 188a20148a1f138a111d8a38322f1c9e
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hex 388a3c33301b8a3f338a2c27248a3a31
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hex 8a271b8a338a35311b0f8a378a383020
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hex 1494328a338a358a378a388a3a8a3c38
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hex 148a3b8a383c2c27941b943f3c382c94
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hex 3d381994312c29258a308a31208a338a
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hex 35292c25943835118a378a38352c2994
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hex 18943c35382c94353d3a16942e29258a
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hex 2d8a2e1d8a308a3129258a3a8a352519
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hex 943a29258a358a22168a3a8a35231794
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hex 332418942c272494381d942c29249437
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hex 1f8a3b8a3e262b298a8a238a8a3e2b29
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hex 268a3f8a3c2b2724a83d2b2722941b94
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hex 3c38148a3b8a383c242c941b943f3c38
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hex 2c943d381994312c29258a308a31208a
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hex 338a352c2925943538118a378a38352c
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hex 299418943c383524943d3a3516942e25
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hex 298a2d8a2e1d8a308a3129258a3a8a35
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hex 2519943a29258a358a22168a3a8a3523
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hex 17943324188a20148a1f138a1d118a38
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hex 322f1c9e388a30333c1b8a3f338a2c27
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hex 248a3a318a271b8a338a35311b0f8a37
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hex 8a30382014a83f3c3814a83320272494
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hex 302c27248a338a2a2724218a308a332a
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hex 21248a308a2e2b27228a338a3722272b
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hex 8a3a8a2b27228a378a332b27228a2e8a
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hex 302d271d94332d241d94372c26228a35
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hex 2c8a26228a332b8a271ba833373a3fa8
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hex 2c2914942b2820248a2c298a188a2b28
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hex 8a292c242094148a308a2c3524208a30
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hex 8a33188a358a3324208a308a2e2b1b94
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hex 2d2a27228a2e2b8a168a2d2a8a2e2b1f
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hex 27941b8a338a372e27228a338a35168a
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hex 378a351f22278a338a35321694343126
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hex 228a35328a1a8a34318a323526229416
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hex 8a388a3c3222268a388a3a1d8a3c8a3a
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hex 2622208a388a3f3327218a3f338a3f33
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hex 2721a83c332721943a331f27942e2b8a
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hex 2e2b8a2e2b942b2e942c2914942b2824
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hex 208a2c298a188a2b288a2c2924209414
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hex 8a308a352c20248a308a33188a358a33
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hex 24208a308a2e2b1b942a2d27228a2e2b
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hex 8a168a2d2a8a2e2b1f27941b8a338a37
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hex 2e271f8a338a35168a378a3527221f8a
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hex 338a3020148a2f8a301d118a3a308a1f
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hex 138a38308a20148a33308a372e22168a
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hex 368a37222b278a3c8a2a27218a3f8a3a
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hex 2b27228a378a332d182494332d1d1194
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hex 372c32228a35322c8a261a8a332e2b8a
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hex 271b942b2e8a2e2b8a2e2b942e2b942c
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hex 1b942216943f3a3733ff
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; Epilogue
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org $fffc
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.word Start
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.word Start
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