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+--- Thread: (20S and 21S) RPN Simulator (/thread-8471.html)
(20S and 21S) RPN Simulator - Eddie W. Shore - 06-08-2017 01:03 PM
This program will allow the user to simulate RPN (Reverse Polish Notation) for five arithmetic functions: addition, subtraction, multiplication, division, and exponentiation (power). All operations take the form of enter Y, press [INPUT], enter X, [XEQ] (appropriate key).
Labels:
XEQ A: Y + X
XEQ B: Y – X
XEQ C: Y * X
XEQ D: Y/X
XEQ E: Y^X
XEQ F: “clears” the stack.
The result shown in the display while the X value is left in the hidden display, which can be accessed by pressing [ LS ] (SWAP).
The key codes for the HP 20S and HP 21S are the same.
Code:
STEP CODE KEY
01 61, 41, A LBL A
02 21, 0 STO 0
03 51, 31 SWAP
04 21, 75, 0 STO+ 0
05 22, 0 RCL 0
06 61, 26 RTN
07 61, 41, B LBL B
08 21, 0 STO 0
09 51, 31 SWAP
10 21, 65, 0 STO- 0
11 22, 0 RCL 0
12 32 +/-
13 21, 0 STO 0
14 61, 26 RTN
15 61, 41, C LBL C
16 21, 0 STO 0
17 51, 31 SWAP
18 21, 55, 0 STO* 0
19 22, 0 RCL 0
20 61, 26 RTN
21 61, 41, D LBL D
22 21, 0 STO 0
23 51, 31 SWAP
24 21, 45, 0 STO÷ 0
25 22, 0 RCL 0
26 15 1/X
27 21, 0 STO 0
28 61, 26 RTN
29 61, 41, E LBL E
30 21, 0 STO 0
31 51, 31 SWAP
32 14 y^x
33 22, 0 RCL 0
34 74 =
35 21, 0 STO 0
36 21, 26 RTN
37 61, 41, F LBL F
38 71 Clear
39 71 Clear
40 61, 26 RTNExample:
In the following examples, 8 will be stored in the hidden register.
7 + 8: 7, INPUT, 8, XEQ A. Result: 15
7 – 8: 7, INPUT, 8, XEQ B. Result: -1
7 * 8: 7, INPUT, 8, XEQ C. Result: 56
7/8: 7, INPUT, 8, XEQ D. Result: 0.375
7^8: 7, INPUT, 8, XEQ E. Result: 5,764,801