pavery
Experienced Member
Greetings all
I thought I'd give my Kaypro II a 'heat soak' test while I waited for another keyboard/parts.
All went well for about 5 hours, then the screen showed wierd characters. On re-boot, the screen just fills with wierd characters, many of them flashing. It obviously doesn't get very far into its boot-up sequence.
Out with the logic probe, I soon discovered /Int was held low, ie active all the time. Pulling the PIOs, I found the printer PIO to be the culprit. However rather ominously, with this PIO out of the circuit and /Int now Hi, the cpu doesn't seem to get any further with boot.
I swapped the PIO with the other (SYSPIO) - no change. I checked clock signals with the scope - fine.
My question is "Should this PIO be trying to Int? There's nothing connected to it, is it trying to get initial settings?"
Where should I go from here?
If you'd like to look at good schematics, these are here.
Many thanks for any assistance
Philip
I thought I'd give my Kaypro II a 'heat soak' test while I waited for another keyboard/parts.
All went well for about 5 hours, then the screen showed wierd characters. On re-boot, the screen just fills with wierd characters, many of them flashing. It obviously doesn't get very far into its boot-up sequence.
Out with the logic probe, I soon discovered /Int was held low, ie active all the time. Pulling the PIOs, I found the printer PIO to be the culprit. However rather ominously, with this PIO out of the circuit and /Int now Hi, the cpu doesn't seem to get any further with boot.
I swapped the PIO with the other (SYSPIO) - no change. I checked clock signals with the scope - fine.
My question is "Should this PIO be trying to Int? There's nothing connected to it, is it trying to get initial settings?"
Where should I go from here?
If you'd like to look at good schematics, these are here.
Many thanks for any assistance
Philip