Reading HP67 ROMs

[teenix]

Hi all,

I have a design for a ROM replacement now. The circuit board measure 11mm x 8mm and should fit where the original 8 pin ROMs were on the CPU board. I was lucky to find a processor chip to use as there are not many around until it seems sometime mid 2023. I have been working on the code but not fully tested yet. As well as act like a ROM it has to decipher a few instructions and then act on those, mainly for transferring RAM etc. The processor can only execute about 6 instruction at certain times during the PHI clocks so it is a bit of a challenge.

I still have a bit to go because testing will take some time.

cheers

Tony