Hello,
Good points. I checked voltage and noticed only approx 20 mV drop during access to the ICs. Only checked one of the ones that were successful in writing. Will check the other ones also. Away from my lab right now so it will take a few days though.
Being an HP design of the 1980-ies, I would expect those issues to be taken care of, but perhaps a failing cap?
All signal lines to the EEPROMS are buffered on the board by the way and the Arduino seems to output levels well within TTL requirements.
I'm thinking if there is something with the IC itself, but wonder if there is really anything that can degrade from age? It is not that the complete IC is dead, but rather just bytes are off.
I know people have updated the firmware, but not sure if this was an immediate success or if this kind of behaviour is common - hoping there may be a workaround...
Regards,
? Staffan?
