Casio CFX-9850GB Plus 32KB WE (White Edition): 64KByte "upgrade" reconfiguration

[Mark]

Interesting, indeed !

You've done a great job Jose, what a lot of photos... I didn't remember the additional ROM module, neither did I about the 3 crystals and resonators on the board, X101 for LSI101 and X102/X103 for LSI104. By the way, X103 has the cylindrical form factor often associated with real-time clocks.

The architecture looks quite complex for such a calculator ; of course I may be wrong, but it clearly seems that we've got here a 2-processor machine (LSI101 : main + LSI104 : I/O ?), each with its own RAM + ROM. The Casio-labeled chip F3660-ZD / LSI105 probably acts as a communication bridge between both CPUs.
A service manual (which I still don't find) would allow us to be sure about what is very hypothetical...

Cheers,
Marc