25) RPN CALCULATOR (734 B)
To use: LOAD 11, RUN

10 REM
20 REM RPN CALCULATOR
30 REM
40 DIM R(5)
50 CLS
60 PRINT "V ";R(5)
70 PRINT "U ";R(4)
80 PRINT "T ";R(3)
90 PRINT "Z ";R(2)
100 PRINT "Y ";R(1)
110 PRINT "X ";R(0)
120 PRINT "ENTER INTEGER OR - + * / ** X"
130 LET X=0
140 INPUT A$
150 IF A$="" THEN STOP
160 LET C=CODE(A$)
170 LET A$=TL$(A$)
180 IF C=220 THEN GOTO 320
190 IF C=221 THEN GOTO 430
200 IF C=222 THEN GOTO 490
210 IF C=223 THEN GOTO 510
220 IF C=226 THEN GOTO 530
230 IF C=61 THEN GOTO 550
240 IF C<28 OR C>37 THEN GOTO 140
250 LET X=C-28
260 GOSUB 590
270 FOR I=0 TO 4
280 LET R(5-I)=R(4-I)
290 NEXT I
300 LET R(0)=X
310 GOTO 50
320 LET C=CODE(A$)
330 IF C<28 OR C>37 THEN GOTO 370
340 GOSUB 590
350 LET X=-X
360 GOTO 270
370 LET R(0)=R(1)-R(0)
380 FOR I=1 TO 4
390 LET R(I)=R(I+1)
400 NEXT I
410 LET R(5)=0
420 GOTO 50
430 LET C=CODE(A$)
440 IF C<28 OR C>37 THEN GOTO 470
450 GOSUB 590
460 GOTO 270
470 LET R(0)=R(1)+R(0)
480 GOTO 380
490 LET R(0)=R(1)*R(0)
500 GOTO 380
510 LET R(0)=R(1)/R(0)
520 GOTO 380
530 LET R(0)=R(1)**R(0)
540 GOTO 380
550 LET X=R(0)
560 LET R(0)=R(1)
570 LET R(1)=X
580 GOTO 50
590 LET C=CODE(A$)
600 IF C<28 OR C>37 THEN RETURN
610 LET A$=TL$(A$)
620 LET X=X*10+C-28
630 GOTO 590