View Single Post
Old 17th Mar 2021, 9:42 pm   #1116
ScottishColin
Octode
 
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,822
Default Re: Non-working Commodore PET 3016

This is what I get on UI10 and UI11 pin1. It doesn't stop after power on. There's no 'normal' square waves that I see.

Colin.


Quote:
Originally Posted by SiriusHardware View Post
From #1111, system RAM looks like it is being written to (pin 19 active) but not read from at all (pin 1 inactive) - or the signal which should be driving pin 1 low is missing in action, possibly. Of course we don't know exactly where the CPU is stuck or what it is trying to do.

Try monitoring UI10 / pin 1 for activity in the period immediately after reset and seeing if there is any activity on it then. If we never see any attempt to write to system RAM there may be a problem with the circuitry that generates the write signal for the system RAM.
Attached Thumbnails
Click image for larger version

Name:	UI10 and UI11 pin 1 20210317.jpg
Views:	42
Size:	42.7 KB
ID:	229432  
ScottishColin is online now