MCODE: Card_Reader 1G ROM

[Ángel Martin]

Recently I've been looking into the Card_Reader 1G ROM to learn more about the section dealing with the HP-67 code conversion.

This ROM is a piece of work, fully packed and stuffed with tons of interesting tricks. Looking at the ROM contents it becomes clear that the Card_Reader was a difficult peripheral to control. I guess the breakthrough was the original models on with the HP-65 and 67, but the 41 implementation is a real masterpiece.

Anyway I was wondering if somebody had already disassembled the HP-67 code conversion part of the ROM, located at addresses E469 to E566 and E5A7 to E608. Those tables appear though to crack, I'd expect them to be some kind of mapping between HP-67 and HP-41 instruction codes but so far I haven't figured it out...

Best,
ÁM