10 REM SIMPLE CALCULATOR
20 LET K = 0 // FIRST ELEMENT          
30 LET L = 0 // SECOND ELEMENT          
40 LET M = 0 // RESULT          
50 LET N = 0 // OPERATOR         
60 LET A = 7 
70 LET X = 4 
80 LET A$ = "7" 
90 LET Y = 4 
100 GOSUB 940 
110 REM GOTO  360
120 LET A = 8 
130 LET A$ = "8" 
140 LET X = X + 6 
150 GOSUB 940 
160 LET A = 9 
170 LET A$ = "9" 
180 LET X = X + 6 
190 GOSUB 940 
200 LET A = 4 
210 LET A$ = "4" 
220 LET X = 4 
230 LET Y = Y + 4 
240 GOSUB 940 
250 LET A = 5 
260 LET A$ = "5" 
270 LET X = X + 6 
280 GOSUB 940 
290 LET A = 6 
300 LET A$ = "6" 
310 LET X = X + 6 
320 GOSUB 940 
330 LET A = 1 
340 LET A$ = "1" 
350 LET X = 4 
360 LET Y = Y + 4 
370 GOSUB 940 
380 LET A = 2 
390 LET A$ = "2" 
400 LET X = X + 6 
410 GOSUB 940 
420 LET A = 3 
430 LET A$ = "3" 
440 LET X = X + 6 
450 GOSUB 940 
460 LET A = 0 
470 LET A$ = "0" 
480 LET X = 4 
490 LET Y = Y + 4 
500 GOSUB 940 
510 LET A = 100 
520 LET A$ = "+" 
530 LET X = X + 6 
540 GOSUB 940 
550 LET A = 101 
560 LET A$ = "=" 
570 LET X = X + 6 
580 GOSUB 940 
585 GOTO 870 // DISPLAY RESULT FIELD
590 GET MOUSE X ,Y ,V 
600 IF V = 1 THEN GOTO 630 
610 WAIT 100 // no user input   
620 GOTO 590 
630 GET MIRROR X ,Y ,V 
640 IF V = 0 THEN GOTO 590 
650 IF V <> 101 THEN GOTO 700 
660 REM PLUS PRESSED
670 LET N = 1 
680 LET M = 0 
690 GOTO 880 
700 IF V <> 102 THEN GOTO 780 
710 REM EQUAL PRESSED
720 BEEP 
730 LET M = K + L 
740 LET K = M 
750 LET L = 0 
760 LET N = 0 
770 GOTO 880 
780 REM DIGIT TYPED 0 ... 9
790 LET V = V - 1 
800 IF N <> 0 THEN GOTO 840 
810 LET K = K * 10 + V 
820 LET M = K 
830 GOTO 870 
840 REM SECOND ELEMENT
850 LET L = L * 10 + V 
860 LET M = L 
870 COLOR WHITE ,ORANGE 
880 CURSOR 4 ,2 
890 PRINT "                 " 
900 CURSOR 4 ,2 
910 PRINT M 
920 GOTO 590 
930 END 
940 REM SUBROUTINE FOR DRAWING  
950 COLOR WHITE ,BLUE 
960 CURSOR X ,Y 
970 PRINT "     " ,
980 CURSOR X ,1 + Y 
990 PRINT "  " ,A$ ,"  " ,
1000 CURSOR X ,2 + Y 
1010 PRINT "     " ,
1020 LET B = 0 
1030 LET D = 0 
1040 MIRROR X + D ,Y + B ,A + 1 
1050 LET D = D + 1 
1060 IF D < 5 THEN GOTO 1040 
1070 LET B = B + 1 
1080 IF B < 3 THEN GOTO 1030 
1090 RETURN