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A pair of Pets - Preparing to test after perhaps 40 years unused

The outside temperature may be cool, but trying to capture 12-bits of an address bus, 8 bits of data and syncing with the kernal CS and CPU reset has created a decidedly warm temp at my bench.

All I've determined today is:

1) The initial address is usually FFFC, but not always
2) CS on the kernal sometimes just continues when it should stop to move to the PETTESTER
3) My test clips are horrible & I need longer and softer test cables so they don't keep popping themselves off
4) I perhaps don't have the patience to make this particular tapestry with an 8 channel analyser

I might take some time away from this and consider buying a 32 channel tool.
 
Hi - I've returned with a week off work which will allow me to put a bit of time into this Universal 8032.

I've not touched this since July and while I don't have a bigger Logic Analyser, I do have a ROMulator. With it's default programming the startup 'chirp' has returned to the machine. No screen output though - signals on CRTC drive signals are not healthy (H is about 4Khz and V fluctuates in the 100's of Khz). I've kept the screen disconnected since the initial attempt and seeing that.

I'm currently trying to get my RaspberryPi setup right to let me program the ROMulator for a 50Hz 8032...I'm finding that the docs might be a little out of date so don't seem to work on recent Debian distros, and looking for WiringPi which is apparently no more. I'll keep working through this and hopefully work out how to get it going and configured for my machine.

My main reason for posting today is from reading a post today about editing PETTESTER v4 for 50 or 60Hz.

My machine is 50Hz but I had been using PETTESTER as downloaded. It had seemed to work fine for a few days and helped us find and fix a couple of faults until my screen went off in the middle of showing my "g" and "b" RAM. Looking at positions 9, A, C in the binary I'd used to burn it, I seem to be set for 60Hz. Could that have worked for a while and then caused damage?
 
I've used a 60hz EPROM on a 50Hz machine with no I'll effects. The only issue I saw was a screen wobble. Others may have a better view but it's no issue here. I have had a PET that had a screen problem that I tracked down to the cable from the motherboard. Have you given that a wiggle?
 
ScottishColin said:
I've used a 60hz EPROM on a 50Hz machine with no I'll effects. The only issue I saw was a screen wobble. Others may have a better view but it's no issue here. I have had a PET that had a screen problem that I tracked down to the cable from the motherboard. Have you given that a wiggle?
Click to expand...
Thank you, and hopefully that's the case for me. It was just something I saw in another thread as I tried to get my head back into this repair.

It won't be the cable in this case, the signals off the actual CRTC (and the connector) are garbage right now, but I appreciate the reminder to consider the simple things first.
 
Yes, the 50 Hz and 60 Hz refer to the video frame refresh rate and not the mains frequency.

Although, under certain lighting conditions, you may get some objectionable artefacts.

I can't actually see why any disparity would cause any screen 'wobble'.

Solder joint ring cracking is a common occurrence.

Dave
 
I managed to get Romulator to compile. It was quite a saga involving much trial and error across multiple Pi 3 and 4bs, and various versions of Debian, Ubuntu and sources for WiringPi. For anyone else finding similar struggles, I ended up using a Pi4b, 64-bit Debian Bullseye & WiringPi 2.6.

I used an existing 8032 50Hz config but put it on config "0" because I wasn't really sure about config settings beyong 16 as everything seems to refer to there being 4 DIP switches...I figured "all off' was easiest to be sure about. If I've used the correct settings, this is with all but the char ROM mapped, and memory mapped.

I still get the start-up chirp but video measurements on J7 are still bad:

Pin 3 (V) fluctuates 100-200KHz (yes, K)
Pin 5 (H) steady 4.6 KHz

I have some UM6845RA so so decided to try them. I don't know that they work but I got them from a local eBayer who seems to be an anthuasiast so presumably real.

Trying two different ICs, I get:

Pin 3 (V) 10 Hz
Pin 5 (H) steady 4.6 KHz

Clearly still "wrong".

Now that I have the romulator, I'm thinking that making the right combinatoin of config sets so I can work out what's good and what's bad (in terms of real ROMs and RAM) would be a good start. I'm also interested in seeing if the ROMulators pseudo video display now works for the 8032. The docs all suggest it's PET 2001 only but that was years ago.

edit....from ROMUlators virtual display!:

1735625611844.png
 
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