By then, the EEPROM was no longer available, and Yaesu had exhausted its inventory. Transceiver control applications that used the undocumented instructions to frequently modify that additional radio state eventually wore out the EEPROM, bricking the radio. + The EEPROM - 'Electrically Erasable Programmable Read Only Memory' - used in these radios has a lifetime limit on updates - clearly stated in its spec sheet. + This led to similar discovers for the FT-857 and FT-897. + These undocumented instructions made it possible for transceiver control applications to track and modify that additional radio state. + Many years ago, KA7OEI discovered an undocumented pair of instructions for reading and writing the FT-817's EEPROM, and discovered the locations in that EEPROM that controlled radio state not accessible via its documented CAT instruction set: Yes I did find the HRD notifiocation regarding removing the agc etc commands at Yaesu's request due to them apparently damaging a ram chip (I think).
