UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Non-working Commodore PET 3016

dave cox · 1st Mar 2021, 5:10 pm

I think you proved earlier that the CPU was running through the whole address range (activity on A0-A15) so the PROM UD6 *should* be selected (pin 20 low) at some point. I would be following the pcb trace/continuity from UD6/20 back to whatever drives it - it will some kind of address decoder, but i can't find a handy schematic to go further !

dc

1st Mar 2021, 5:10 pm	#725
dave cox Nonode Join Date: Jan 2009 Location: Bristol, UK. Posts: 2,062	Re: Non-working Commodore PET 3016 I think you proved earlier that the CPU was running through the whole address range (activity on A0-A15) so the PROM UD6 should be selected (pin 20 low) at some point. I would be following the pcb trace/continuity from UD6/20 back to whatever drives it - it will some kind of address decoder, but i can't find a handy schematic to go further ! dc