BASE

 100 PRINT "ADD ONE OF THESE PREFIXES TO NO.B=BINARY   D=DECIMAL            O=OCTAL    H=HEX"
 110 INPUT N$
 120 LET B$=N$(1)
 130 LET N$=N$(2 TO LEN N$)
 140 IF B$="B" THEN LET BB=2
 150 IF B$="O" THEN LET BB=8
 160 IF B$="D" THEN LET BB=10
 170 IF B$="H" THEN LET BB=16
 180 IF BB<>10 THEN GOSUB 500
 190 IF BB=10 THEN LET ND=VAL N$
 200 IF BB<>2 THEN LET B=2
 210 GOSUB 400
 220 LET M$=Y$
 230 IF BB=2 THEN LET M$=N$
 240 IF BB<>8 THEN LET B=8
 250 GOSUB 400
 260 LET O$=Y$
 270 IF BB=8 THEN LET O$=N$
 280 IF BB<>16 THEN LET B=16
 290 GOSUB 400
 300 LET H$=Y$
 310 IF BB=16 THEN LET H$=N$
 320 PRINT "NUMBER IN OTHER BASES"
 330 PRINT "DECIMAL:";ND
 340 PRINT "BINARY :";M$
 350 PRINT "OCTAL  :";O$
 360 PRINT "HEXADEC:";H$
 370 STOP 
 380 GOTO 100
 400 LET Z=ND
 410 LET Y$=""
 420 LET Y=Z
 430 LET Z=INT (Z/B)
 440 LET Y=Y-B*Z
 450 LET K=28
 460 IF Y>9 THEN LET K=21+(7*(B=16))
 470 LET Y$=CHR$ (Y+K)+Y$
 480 IF Z>0 THEN GOTO 420
 490 RETURN 
 500 LET ND=0
 510 LET Z=0
 520 FOR I=1 TO LEN N$
 530 LET Z=CODE N$(I)
 540 LET K=28
 550 IF Z>37 THEN LET K=21+(7*(BB=16))
 560 LET ND=ND*BB+Z-K
 570 NEXT I
 580 RETURN 
\n9550 CLS 
\n9560 SAVE "BAS%E"
\n9570 GOTO 100