jjlonbass wrote:Which microcontroller is missing? There are 2 - one, a 8049, is the "key assigner" and the other, a 8048, is the "programmer".
Both are mask programmed i.e. the software is hard-wired into the chip - there is no separate PROM. This means that you need the exact correct 8049 or 8048 part containing the correct software. Any old 8049 or 8048 won't work.
I suspect that these will be very difficult to find.
It's the 8049 that's missing. I was suspicious of how easy it was to find one - but now I know why. Again - your advice/direction is very helpful!