Hi all!
I just got the PIC-based rom emulator done. It consists of a PIC 18C252 processor running at 40MHz and an EPSON SG-8002DC-PWT programmable oscillator (programmed for 40MHz).
The code is very straightforward, just bit-banging everything in and out of the serial buses. It needs some trimming, and also figuring out how to make it play nice with the calculator in standby/poweroff modes (I can't have the thing drawing 50mA when the calculator is off!), but that shouldn't be hard.
Look in [http://www.tla.org/hp41/mldl.html] for pretty pictures. I'll be putting the code there when I'm ready to release it.
/ji