C64-dev/examples/sound-demo.bas

1 REM =============================================
2 REM  SOUND-DEMO.BAS — C64 SID Chip Sound Demo
3 REM  Demonstrates: 3-voice music, ADSR, waveforms
4 REM =============================================
10 SID = 54272  : REM SID base ($D400)
20 VOL = SID+24 : REM master volume ($D418)
30 POKE VOL, 15 : REM Volume = 15 (maximum)

100 REM --- PLAY A SIMPLE MELODY (Voice 1) ---
110 REM Frequency values for NTSC C64
120 REM C4=4313, D4=4842, E4=5431, F4=5760, G4=6433, A4=7372, B4=7992, C5=8627

130 DIM NOTE%(7)
140 NOTE%(0) = 4313 : REM C4
150 NOTE%(1) = 4842 : REM D4
160 NOTE%(2) = 5431 : REM E4
170 NOTE%(3) = 5760 : REM F4
180 NOTE%(4) = 6433 : REM G4
190 NOTE%(5) = 7372 : REM A4
200 NOTE%(6) = 7992 : REM B4

210 REM ADSR for voice 1: fast attack, short decay, sustain 12, medium release
220 POKE SID+5, 9   : REM attack=0(2ms), decay=9(250ms)
230 POKE SID+6, 192 : REM sustain=12, release=0

240 REM Sawtooth waveform
250 WAVEFORM = 32   : REM %00100000 = sawtooth

300 REM --- MELODY LOOP ---
310 FOR I = 0 TO 6
320   F = NOTE%(I)
330   POKE SID, F AND 255        : REM frequency low
340   POKE SID+1, INT(F/256)     : REM frequency high
350   POKE SID+4, WAVEFORM OR 1  : REM start note (gate on)
360   FOR W = 1 TO 150 : NEXT    : REM hold note
370   POKE SID+4, WAVEFORM       : REM release (gate off)
380   FOR W = 1 TO 50 : NEXT     : REM short gap
390 NEXT I

400 REM --- 3-VOICE CHORD (C major) ---
410 PRINT "PLAYING C MAJOR CHORD..."
420 REM Voice 1: C4
430 POKE SID, 4313 AND 255 : POKE SID+1, INT(4313/256)
440 POKE SID+5, 2 : POKE SID+6, 240 : REM slow attack, sustain 15
450 POKE SID+4, 33  : REM triangle + gate

460 REM Voice 2: E4
470 POKE SID+7, 5431 AND 255 : POKE SID+8, INT(5431/256)
480 POKE SID+12, 2 : POKE SID+13, 240
490 POKE SID+11, 17 : REM triangle + gate (voice 2 control = SID+11)

500 REM Voice 3: G4
510 POKE SID+14, 6433 AND 255 : POKE SID+15, INT(6433/256)
520 POKE SID+19, 2 : POKE SID+20, 240
530 POKE SID+18, 17 : REM triangle + gate (voice 3 control = SID+18)

540 FOR W = 1 TO 500 : NEXT : REM hold chord

550 REM Release all voices
560 POKE SID+4, 16   : REM voice 1 release
570 POKE SID+11, 16  : REM voice 2 release
580 POKE SID+18, 16  : REM voice 3 release
590 FOR W = 1 TO 300 : NEXT

600 REM --- NOISE EFFECT (explosion) ---
610 PRINT "EXPLOSION SOUND..."
620 POKE SID+5, 0 : POKE SID+6, 0  : REM instant attack+decay+release
630 POKE SID, 255 : POKE SID+1, 255 : REM high frequency for noise
640 POKE SID+4, 129 : REM noise + gate (%10000001)
650 FOR W = 1 TO 100 : NEXT
660 POKE SID+4, 128 : REM gate off

700 REM --- CLEAN UP ---
710 FOR W = 1 TO 200 : NEXT : REM wait for release
720 POKE VOL, 0     : REM silence
730 PRINT "DONE."