Use It

Eleven-yeah-old Keith Goode of Arlington, Texas, certainly gives you your money’s worth with this program. In the menu, Use It presents you with, you can choose one of seven options. The first turns your computer into a drawing board. Option two draws sine wave curves. Three, four, five and six convert your keyboard into a mini-calculator. And finally, just for fun, if you choose option 7, Keith has your computer show you its entire character set. Thanks, Keith, for showing us what you can make your machine do. (T/S1OOO,ZX81 16K)

10 PRINT "USE IT"
20 PRINT "BY KEITH GOODE"
30 PAUSE 200
40 CLS
50 PRINT "MENU:"
60 PRINT
70 PRINT "1 > PLOTTER"
80 PRINT "2 > SINE WAVE"
90 PRINT "3 > ADD"
100 PRINT "4 > SUBTRACT"
110 PRINT "5 > MULTIPLY"
120 PRINT "6 > DIVIDE"
130 PRINT "7 > CHARACTER LISTING"
140 PRINT "8 > BULLETIN BOARD"
150 PRINT "9 > QUIT"
160 INPUT A$
170 IF A$="1" THEN GOTO 1000
180 IF A$="2" THEN GOTO 2000
190 IF A$="3" THEN GOTO 3000
200 IF A$="4" THEN GOTO 4000
210 IF A$="5" THEN GOTO 5000
220 IF A$="6" THEN GOTO 6000
230 IF A$="7" THEN GOTO 7000
240 IF A$="8" THEN GOTO 8000
250 IF A$="9" THEN GOTO 9000
605 CLS
1000 CLS
1010 INPUT A
1020 INPUT B
1030 PLOT A,B
1040 GOTO 1010
2000 CLS
2010 FOR Z=0 TO 63
2020 PLOT Z,22+20*SIN(Z/32*PI)
2030 NEXT Z
2040 PAUSE 150
2050 CLS
2060 GOTO 50
3000 CLS
3010 INPUT C
3020 INPUT D
3030 PRINT C+D
3040 PAUSE 200
3050 CLS
3060 GOTO 50
4000 CLS
4010 INPUT E
4020 INPUT F
4030 PRINT E-F
4040 PAUSE 200
4050 CLS
4060 GOTO 50
5000 CLS
5010 INPUT G
5020 INPUT H
5030 PRINT G*H
5040 PAUSE 200
5050 CLS
5060 GOTO 50
6000 CLS
6010 INPUT I
6020 INPUT J
6030 INPUT I/J
6040 PAUSE 200
6050 CLS
6060 GOTO 50
7000 CLS
7010 FOR X=0 TO 255
7020 PRINT CHR$ X
7030 NEXT X
7040 CLS
7050 GOTO 50
8000 CLS
8010 INPUT M$
8020 PRINT M$
8030 GOTO 8010