Register 25 gives you access to the output of the envelope generator of oscillator 3. It functions in much the same fashion that the output of oscillator 3 does. The oscillator must be turned on to produce any output from this register.

Vibrato (a rapid variation in frequency) can be achieved by adding the output of oscillator 3 to the frequency of another oscillator. Example Program 6 illustrates this idea.

EXAMPLE PROGRAM 6:

 10 S=54272
 20 FORL=0TO24:POKES+L,0:NEXT
 30 POKES+3,8
 40 POKES+5,41:POKES+6,89
 50 POKES+14,117
 60 POKES+18,16
 70 POKES+24,143
 80 READFR,DR
 90 IFFR=0THENEND
 100 POKES+4,65
 110 FORT=1TODR*2
 120 FQ=FR+PEEK(S+27)/2
 130 HF=INT(FQ/256):LF=LQAND255
 140 POKES+0,LF:POKES+1,HF
 150 NEXT
 160 POKES+4,64
 170 GOTO80
 500 DATA4817,2,5103,2,5407,2
 510 DATA8583,4,5407,2,8583,4
 520 DATA5407,4,8583,12,9634,2
 530 DATA10207,2,10814,2,8583,2
 540 DATA9634,4,10814,2,8583,2
 550 DATA8583,12
 560 DATA0,0