Decimal Code Poker

   5 REM USE GOTO 10 NOT RUN
  10 PRINT "BASE ADDRESS: ";
  20 INPUT B
  30 PRINT B
  40 PRINT "NO.OF DATA BYTES: ";
  50 INPUT D
  60 PRINT D
  70 FOR I=0 TO D-1
  80 POKE B+I,0
  90 NEXT I
 100 LET A=B+D
 110 PRINT "CODE:"
 120 INPUT C$
 130 IF C$="S" THEN GOTO 180
 140 PRINT C$
 150 POKE A,16*(CODE C$(1)-28)+CODE C$(2)-28
 160 LET A=A+1
 170 GOTO 120
 180 CLS 
 190 FOR I=1 TO 9
 200 POKE I-1+A,M(I)
 210 NEXT I
 220 STOP 
 230 SAVE "1024%6"
 240 GOTO 5