SID 3-VOICE TEST PROGRAM     3-13-2012

     For those wishing to test the 3 voices of the SID chip, here is
a BASIC program to do that:

 5 REM C64 SID 3-VOICE TEST PROGRAM
 10 FORL=54272TO54296:POKEL,0:NEXT:POKE54296,15:GOSUB60
 20 POKEW,17:POKEA,9:POKEHF,15:POKELF,35:POKES,128:GOSUB50:GOSUB70
 30 POKEW,17:POKEA,9:POKEHF,20:POKELF,40:POKES,128:GOSUB50:GOSUB80
 40 POKEW,17:POKEA,9:POKEHF,25:POKELF,50:POKES,128:GOSUB50:GOTO10
 50 FORX=1TO2000:NEXTX:RETURN
 60 W=54276:A=54277:HF=54273:LF=54272:S=54278:RETURN
 70 W=54283:A=54284:HF=54280:LF=54279:S=54285:RETURN
 80 W=54290:A=54291:HF=54287:LF=54286:S=54292:RETURN 

     Line 10 resets the SID and POKEs maximum volume to the three voices.
Line 20 POKEs values to voice 1 and plays a note for a few seconds. Line
30 adds voice two and plays a note mixed with voice 1 for a few seconds.
Line 40 adds the third voice to the first two for a few seconds, then the
program loops back to the beginning. The parameters for the three voices
are in the subroutines in lines 60, 70 and 80. The subroutine in line 50
adds a delay so each voice can be monitored as the program advances. If 
any/all of the voices are missing or sound "muddy", suspect a bad SID. 

Ray Carlsen