[PETERg0rsq]

Yes a decent logic analyser is a big help, and I use it lots, especially for TTL and CMOS logic circuits.

I also use it to read data BUS, and Multiplexed display signals to locate issues.

However on this occasion I probably relied on it too much, as if I had used a scope earlier, to verify all the levels then probably I would have saved a lot of time. The logic analyser was showing the 6801 levels, but I never verified that they were also being seen at the other chips!

It was, however great for understanding how the CPU board worked, and I now have a basic understanding on how a MCU communicates with its ROM etc. Every cloud etc.

When i get some time i will do some more reading on understanding the internal functions of the MCU.

Now to clear the backlog of other equipment i need to repair. I think what I have learnt is going to come in useful.

Peter