100 REM  MICHEAL MCCABE  
110 REM  RETROCHALLENGE 2021      
120 REM  DTMF TONE GENERATOR      
130 CALL CLEAR
135 OPTION BASE 0
140 DIM F(16,3)
150 RESTORE
160 DATA 941,1336,100
170 DATA 697,1209,100
180 DATA 697,1336,100
190 DATA 697,1477,100
200 DATA 770,1209,100
210 DATA 770,1336,100
220 DATA 770,1477,100
230 DATA 852,1209,100
240 DATA 852,1336,100
250 DATA 852,1477,100
260 DATA 941,1209,100
270 DATA 941,1477,100
272 DATA 697,1633,100
274 DATA 770,1633,100
276 DATA 852,1633,100
278 DATA 941,1633,100
280 FOR I=0 TO 15
290 READ F(I,1),F(I,2),F(I,3)
300 NEXT I
310 PRINT "DTMF TONE GENERATOR FOR"
320 PRINT "CO DIALING"
330 PRINT
340 PRINT "ENTER A STRING OF DIGITS"
350 PRINT "FOR THE DESTINATION PHONE"
360 PRINT "NUMBER:"
370 PRINT
380 INPUT D$
390 PRINT
400 PRINT "THANK YOU."
410 PRINT
418 PRINT "SENDING DIGITS..."
420 FOR I=1 TO LEN(D$)
430 LET E$=SEG$(D$,I,1)
440 GOSUB 550
443 CALL SOUND(F(D,3),F(D,1),7,F(D,2),7)
450 NEXT I
460 PRINT
500 PRINT "TONE SEQUENCE COMPLETE."
510 PRINT
520 INPUT "RUN AGAIN?":Q$
530 IF (Q$="Y")+(Q$="YES")THEN 330
540 END
550 REM  PARSE THE DIGIT 
560 LET A=ASC(E$)
570 IF (A>=48)*(A<=57)THEN 650
580 IF (A>=65)*(A<=68)THEN 680
590 IF A=35 THEN 710
600 IF A=42 THEN 740
610 PRINT "PARSE ERROR."
620 STOP
650 REM  CASE 1 
660 LET D=A-48
670 RETURN
680 REM  CASE 2 
690 LET D=A-53
700 RETURN
710 REM  CASE 3 
720 LET D=11
730 RETURN
740 REM  CASE 4 
750 LET D=10
760 RETURN