Bulls and Cows
Choosing a four digit number, the computer will respond to your guesses (or deductions, we hope) by displaying a bull when you get a correct digit in the right place, and a cow when a number you input also occurs in the computer's number, but not in the same place. You should note that the computer's number can have the same digit repeated.
You can choose the number of guesses you're allowed, making it more difficult for yourself as you get more practised.
10 REM BULLS AND COWS
20 REM @ ROBERT ERSKINE
30 MODE 1
40 BORDER 0:INK 0,0:INK 1,24:INK 2,20:IN K 3,8:PAPER 0:PEN 1:CLS
50 LN=1
60 SYMBOL 251,0,2,3,255,126,126,66,66 70 SYMBOL 252,0,0,3,255,126,126,66,66 BOY GOTO 750
90 DIM N(4), A(4),H(4)
100 LN=1: R=RND:LOCATE 4,14:PRINT" HOW M ANY GUESSES DO YOU WANT";:INPUT T
110 GOSUB 380
120 CLS: LOCATE 10,14:PRINT"I HAVE CHOSE N A NUMBER":FOR X= 1 TO 1000:NEXT
130 GOSUB 430
140 FOR 0 = 1 TO T
150 LOCATE 1,23: PRINT"ENTER YOUR GUESS NOW E4 DIGITSJ";:INPUT G$:IF LEN (G$)<>4
THEN LOCATE 32,23:PRINT SPACE$(7);:GOTO
150
160 FOR F=1 TO 4:IF ASC(MID$(G$,F,1))<48
OR ASC(MID$(G$,F,1))>57 THEN LOCATE 32, 23:PRINT SPACE$(7);:GOTO 150:NEXT F
170 LOCATE 32,23:PRINT SPACE$(7);
180 GOSUB 250
190 GOSUB 460
200 IF BLACK<4 THEN NEXT 0:FOR X=1 TO 30 0:NEXT X:GOTO 600