Is there a free RPN stack emulator for writing 35s programs


Does anyone know of a free RPN stack emulator for the HP 35s? I'd love to write some more programs for myself, but it's so time consuming. It would be great if I could see all the values in the stack and in memory locations at all times, see code changes and their results instantly, and have keystrokes recorded automatically so I didn't have to stop and write, or erase and rewrite, them. Am I dreaming?

Edited: 5 Nov 2012, 9:26 p.m.


Short answer: yes, long answer: yes, there is. Well, at least, there once was such a thing, showing the stack and some registers. It was programmable using commands like the HP41 and was a nice toy to watch computing, moving X to LastX, droping the stack, etc.

It must be somewhere on my elder disks, I will look for it.



RPNdemo from John Kennedy is an emulator in an other sense as all others here. From the manual: RPNDEMO is NOT intended to be an HP-41 simulator, but where possible the instruction set matches that of the HP-41 exactly. With few exceptions RPNDEMO includes most of the programming capabilities of the HP-41. This DOS program shows an animated view of the stack movements during operation. So it may help you to explain RPN to a novice or for testing stack usage for a routine fragment. To see the animation on fast PCs you need to call it from a slow-down.BAT:

SLOW -f1 50000 -f2 30000>nul

Alas the links to TP7P5FIX ( and SLOW ( are broken, hope you find new ones. The first is a 'Fix for "Runtime Error 200" bug of Borland Pascal 7 on fast PCs' and the second is just a slow-down tool for old DOS programs if you like to watch the animation.



Thanks a lot, Mike. I appreciate it!


Glad you like it. Could you please tell me where you found the necessary fix and slowdown routine?



Well... I was actually thanking you for your reply and the info you shared. I'm sorry to say that I didn't actually try it. I don't know a whole lot about those kinds of things, so I was hoping for more of a ready-to-go emulator.


Well, I did not read your question carefully:

Does anyone know of a free RPN stack emulator for the HP 35s?

I know only emulators of RPN calculators for DOS, Windows, Unix, iOS, ... - :)


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