Broken calculator

[hjalfi]

Er, yes, FX-850P. Sorry!

I have a PSoC5 development board, which is a 5V ARM with a mini FPGA attached; it has a million GPIO ports and should be relatively easily modifiable into a bus snooper and ROM/RAM emulator. Of course, as it's Harvard architecture with separate code and data address spaces there's no guarantee that I'll see code accesses on the external bus, but it's worth a try. I've found a reference in the short-lived Poche Computers magazine that the HD62002 has 20kB of code ROM, so if I'm very very lucky I can force the CPU to jump to an unused part of the code ROM and use the PSoC to simulate my own ROM code...

Thanks for the links; your videos are really interesting. I knew about Piotr Piatek and had dropped him a note, as I'm curious about how he managed to read 16-bit instruction words from an 8-bit bus. I'll see what he says.