CLASSIC RPN Calculator Simulators - Updated


Since I've found this forum useful and gained from the knowledge shared by other contributors I thought it would be nice to be able to be able to give something back, so for those of you who have always wondered what it was like to use some of the older HP calculators the links below will allow you to download the latest version of my RPN Calculator simulator for Windows.

This release is a development of an earlier beta release of an HP33C simulator, but I've completely rewritten it and expanded it to be able to include a number of different models including the HP10C, HP21, HP25C, HP29C, and HP31E in addition to the original HP33C.

Download the HP21 simulator here - updated 31 Jan 08.

HP22 work in progress...

Download the HP25C simulator here - updated 31 Jan 08.

Download the HP29C simulator here - updated 31 Jan 08.

Download the HP31E simulator here - updated 31 Jan 08.

Download the HP33C simulator here - updated 31 Jan 08.

Download the HP10C simulator here - updated 31 Jan 08.

HP11 work in progress...

The source code (Visual BASIC 5.0) can be found here - updated 31 Jan 08.

The readme file can be found here

To run any of the simulators extract the contents of the ZIP file to a folder and just double click on the appropriate executable. It will run on Windows NT 4.0¹, Windows 2000 and Windows XP (but NOT Windows 95/98/Me) providing that the Visual BASIC 5.0 runtime is installed (it is installed by default with Windows 2000 and XP).

Have fun - your feedback and comments are very welcome. If you find a bug (other then something covered in the known issues) then if you let me know and I'll try to fix it as soon as possible.

Mike T.

¹ Windows NT 4.0 can only run a maximum of three different simulators at any time.

Edited: 31 Jan 2008, 7:19 p.m. after one or more responses were posted


I just tried the 25c. Works great. I'll give the others a go, and thanks for posting these. Excellent work.

Edited: 26 Jan 2008, 11:17 p.m.


Thanks for the fine work.

Two problems:

1) The window stays on top of all other windows. Can that be changed?

2) There is no way to terminate the program. It stays in the task bar. Did I overlook something?

Edited: 27 Jan 2008, 1:04 p.m.


I decided that to keep the window on top unless it was minimized. To exit, try right clicking on the form (or if minimized the task bar icon) - that will bring up a menu...

If you really want I could compile a version that acted like a normal windows application.

Mike T.

Edited: 28 Jan 2008, 4:14 p.m.



You virtual calculators are awsome!!! I love them. I know it's not a snap to write one, but keep up the good work my friend.

Any option to save a program that one keys in to a file on the PC?



On exiting the simulator it saves its current state to an INI file, to keep this for future use simply rename it from and INI file to a PRG file.

Use the load option on the menu to load a previously saved program (right click to bring up the menu).

Mike T.



Thanks for the tip. That's easy to do.

I did find the load option and it makes these virtual calculators awesome and flexible,


Edited: 27 Jan 2008, 7:18 p.m.


These are indeed awesome!

I know this can represent a great deal of effort. It's really appreciated. Keep it up, I would love to see a few more examples.

I stumbled upon a possible bug. I tried to gauge the accuracy by doing: 9 sin cos tan tan-1 cos-1 sin-1

I found that I got 0.00 after pressing cos

A little experimentation showed that taking the cosine of a number less than 0.5 resulted in 0. Numbers even slightly larger seemed to give expected results. Odd behaviour. I looked briefly at the source, but didn't get anywhere. Any ideas?


Thanks - That definatly looks like a problem somewhere. I'll try to post an update in the next couple of days.

Mike T.


All sorted - I took to opportunity to tidy the code up a bit as well.

Thanks for letting me know about the problem.

Mike T.


Very nice Mike.

I'm looking forward to the HP-11C, and more examples!

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