The first alpha release of Nonpareil, a multi-architecture microcode-level calculator simulator and microassembler, is now available:
http://nonpareil.brouhaha.com/
Nonpareil obsoletes CASMSIM. Initially it supports the same Classic series calculators (HP-35, HP-45, HP-55 and HP-80), and one Woodstock series calculator, the HP-25.
There are known bugs; for instance, the logarithmic and exponential functions of the HP-25 are not working correctly. I expect to fix that in the next release.
Future releases will include HP-41C and Voyager series support, based on code from NSIM. And possibly Spice series support; I have to investigate how much Spice differs from Woodstock architecturally.
The display interface between the GUI and the processor simulation is still not very general; in order to add HP-41C support I'll probably have to completely replace it.
Edited: 8 Apr 2004, 3:18 p.m. after one or more responses were posted