Re: 2445 EPROMs
Hi Chris,toggle quoted messageShow quoted text
My humble apologies, the CPU uses a 5MHz square wave clock. The
processor is a 68A02.
Early microprocessors usually took several cycles per instruction.
5, I think was the minimum for the 6800 family... leading to a 200ns
requirement on access time.
It has been a long, long, time since I last had to design with, or
debug a 6800 series microprocessor. I have never found one bad in
all of the 2465's I have calibrated... actually, I have never found
one bad in anything I have worked on.
200ns is what tektronix used as the access time for the RAM, and EPROM.
I would put the probably that the EPROM is good at 99.999%... unless
you have had a power supply problem that has elevated the 5V to above
7V... in which case, most everything on the CPU card will be bad.
Look instead at the jumpers on the board. There are test jumpers that
will prevent boot up.
Also, look at the reset circuitry. A single bad part, and the CPU
will never get out of power on reset. Pay particular attention to the
0.1uf and 2.2M resistors that provide the timing.
Assuming that there is CPU activity, there should be an LED lit on the
front panel indicating the failure cause.