I remember asking Skip about that, way back when..... he will be back and fill us in I sure.
As I recall he saqid that the timing was? a challenge. I think he uses the EEPROM in the 16F877? ( I dont recall which PIC for sure and I dont know where I put the Xcat schematic? ATM). The X runs really slow ~1 mhz, and doesnt have any "houskeeping" duties. so sneaking in to write to the onboard EEPROM between having to serve EEPROM data to the uC on request was comparitively easy. The X9000 is somewhat faster and is using the addy/data lines all the time.
