nsim: HP-41CV Microcode-Level Simulator


nsim is a microcode-level simulator for the HP-41CV programmable scientific calculator. It is written in C and uses the X window system for display.

The functionality of nsim has been merged into my multi-architecture calculator simulator Nonpareil. I consider nsim to be obsolete, and no longer maintain it. It is provided here for historical interest.

nsim is made available under the terms of the Free Software Foundation's General Public License, Version 2.

Source code is available for download.

nsim development uses the Subversion revision control system. Instructions for access to the Subversion repository for Altogether are found at http://svn.brouhaha.com/, and there is a web interface to browse the repository at http://svn.brouhaha.com/viewcvs/nsim/.

nsim screenshot

Third party nsim enhancements and ports

There is a Mac OS X port of nsim by Maciej Bartosiak. He has significantly improved the appearance, and his work on the 41C and other models is being incorporated into Nonpareil.

Christophe Gottheimer has fixed the bank switching and added support for the HEPAX module to nsim release 0.61. His modified source code is available on the download page.

Experimental Voyager Support

The HP "Voyager" series of calculators, including the HP-10C, HP-11C, HP-12C, HP-15C, and HP-15C, used the same "Nut" microprocessor as the HP-41C. I've begun work on adding Voyager simulation capability to nsim. It is not yet fully functional, but it does get as far as displaying "Pr Error" then a cleared X register.

Since it is not yet usable, I haven't packaged a release, but the source code is in the Subversion repository in branch/voyager.

Note that my newer simulator, Nonpareil, includes working Voyager support.

nsim 16C screenshot

Another nsim

The Liberouter project includes an interesing program also called nsim, which is a generic compiler, simulator, and debugger for "nanoprocessors" implemented in FPGAs.

Last updated May 27, 2005

Copyright 1995, 2003, 2004, 2005 Eric Smith


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