The full original simulation lets you play against the machine just as one could against the original, and it has slow and manual modes that will display the instruction steps as they are executed.
It may also be of interest that, internally, the program is built like the original. The logic is performed by "Gates" and "Flip-Flops", just as in the hardware. (Except of course that the 'parallel' logic has actually to execute sequentially . And only the 'game engine' is programmed this way. Interaction with the user is through more conventional GUI techniques.) Where a detailed description of the original logic was available, the simulation follows it almost exactly.
You can download a standard zip archive of the complete package below. (Although the program only runs under BeOS/HAIKU, the accompanying extensive documentation is in HTML form, and might be of interest to some.) The archive is freely distributable at no charge.
Apparently, judging from the 'demo' currently posted on YouTube, it isn't as easy to figure out how to properly operate the simulation as I had hoped. For some quick guidance on how to use the basic functions, see this hints page.
nimrod.zip (384KB)Download the archive for ppc BeOS R5 here:
nimrod_ppc.zip (354KB)PLEASE NOTE: The program needs R5 of BeOS — or HAIKU — to run.
The archive is a 'zip' file which will unpack (using some variant of the 'unzip' program -- available for all operating systems) into a single NIMROD folder, which you can place anywhere. You'll need a little under 500K of disk space to hold it.
BeOS was one of the most advanced — and under used! — operating systems available. On a personal note, I (still) find it the most congenial environment to work in, so it was the only choice for this project.
Now — as of 14 September 2009, with the first public release — the Be OS lives again as 'HAIKU'. HAIKU is a freely available, open-source, recreation of the system, and it runs the major fraction of BeOS programs (including NIMROD) without change. See the above link for all the details.