Start with sys 49152. Press a key to play a note and press F1 to exit.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | + | - |
|---|---|---|---|---|---|---|---|---|---|---|---|
| C | C# | D | D# | E | F | F# | G | G# | A | A# | B |
Taken from The Visible Computer: 6502 by Charles Anderson, pages 124-127, and formatted for the Mikro assembler. Code is copyright Jim Blackshear and Brian Bouldin.
10 *=$c000
19 !
20 note=$fc
30 bgcolor=$d021
40 sid=$d400
50 volume=$d418
60 settim=$ffdb
70 rdtim=$ffde
80 getin=$ffe4
99 !
100 jsr initscrn
110 jsr initsid
120 top jsr getin
130 cmp #$00
140 beq top
150 cmp #$85
160 beq quit
170 jsr chkkey
180 lda note
190 beq top
200 jsr beep
210 jmp top
220 quit rts
299 !
300 initscrn lda #$00
310 sta bgcolor
320 lda #$04
330 ldx #$d8
340 ldy #$00
350 sty $fb
360 sta $fc
370 sty $fd
380 stx $fe
390 ldx #$04
400 loop1 lda #$00
410 sta ($fd),y
420 lda #$a0
430 sta ($fb),y
440 iny
450 bne loop1
460 inc $fc
470 inc $fe
480 dex
490 bne loop1
500 rts
599 !
600 initsid lda #$00
610 ldx #$1c
620 loop2 sta sid,x
630 dex
640 bne loop2
650 lda #$20
660 sta sid+4
670 lda #$f0
680 sta sid+6
690 lda #$0f
700 sta volume
710 rts
799 !
800 chkkey ldx #$00
810 stx note
820 cmp #$2d
830 bne plus
840 lda #$0c
850 sta note
860 rts
870 plus cmp #$2b
880 bne zero
890 lda #$0b
900 sta note
910 rts
920 zero cmp #$30
930 bne cnvt
940 lda #$0a
950 sta note
960 rts
970 cnvt sec
980 sbc #$30
990 cmp #$0a
1000 bcs exit
1010 sta note
1020 exit rts
1199 !
1200 beep ldx note
1210 lda pitchl,x
1220 ldy pitchh,x
1230 sta sid
1240 sty sid+1
1250 ldy #$21
1260 sty sid+4
1270 jsr dbar
1280 ldy #$00
1290 sty sid+4
1300 rts
1999 !
2000 dbar lda #$00
2010 tax
2020 tay
2030 jsr settim
2040 ldx note
2050 lda bsl,x
2060 ldy bsh,x
2070 sta $fd
2080 sty $fe
2090 txa
2100 jsr bar
2110 wait jsr rdtim
2120 cmp #$1e
2130 bne wait
2140 lda #$00
2150 jmp bar
2160 bar ldy #$00
2170 bar1 sta ($fd),y
2180 iny
2190 cpy #$50
2200 bne bar1
2210 rts
2999 !
3000 pitchl byt $00,$61,$e1,$68,$f7,$8f,$30,$da
3010 byt $8f,$4e,$18,$ef,$d2,$00,$00,$00
3020 pitchh byt $00,$08,$08,$09,$09,$0a,$0b,$0b
3030 byt $0c,$0d,$0e,$0e,$0f,$00,$00,$00
3040 bsl byt $00,$70,$20,$d0,$80,$30,$e0,$90
3050 byt $40,$f0,$a0,$50,$00
3060 bsh byt $00,$db,$db,$da,$da,$da,$d9,$d9
3070 byt $d9,$d8,$d8,$d8,$d8