daver2's latest activity

Try changing the oscilloscope synchronising onto the channel used for the address line instead of the NOP EPROM pin 22. And adjust the...

>>> PIN7 (SYNC) LO This indicates that the 6502 CPU is NOT executing instructions. It has probably halted. Dave

Don't forget that you will have to adjust the oscilloscope timebase to 'see' the address line. We are only using the EPROM /CS line as...

So the top trace (the address line) is just mush... You do have a CPU SYNC pulse don't you? Dave

Please stop... These don't look correct... What is the top trace and the bottom trace? Dave

So, I have put together a simple model of the circuit. Interestingly, the model has a 'ghost pulse' as well! Also, occasionally, the...

The bottom line is it may be dictated by the CPU card. If the CPU card is ONLY 16-bit, then it doesn't matter what the backplane is...

I was proposing this previously, but I think we are now finding the faults as we go - and more! The scope traces will be a great...

I think a formal re-write of the Cromemco test protocol is indicated. Also to include scope grabs.

Welcome to the world of PDP-11 machines... I wouldn't start with storage just yet. I would get the CPU, memory and bootstrap working...

Me, having a chicken head as avatar, why didn't I think of that? Thank you!

I think those traces are pretty conclusive. I would suggest leaving the machine at 2 MHz for now and we will have a think about the...

Hmm, The US Patent is different to the Dazzler implementation. I am just wondering if what you are seeing is correct? I will have to...

IC 42/3 is definitely wrong (although I do have a headache and I am getting ready for an early night). We will have to do this the...

This one is somewhat testing - as our usual 'tools' (a NOP generator) no longer appears to work reliably - hence we are having to use...