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Superpet Combo board not working

Mike,

So, is what you are now saying, with a 6809E in the CPU socket (with or without SuperPET ROM?) - that the 8032 works correctly in 6502 mode but you do see something (albeit incorrect) on the screen when in 6809 mode?

Dave
 
Dave,

Yes the 8032 works correctly now with all chips installed on the combo board but when I switch to 6809 mode I have a full screen as shown and in the left center there is actually a flashing, movable cursor. This is with a 6809E and ROM U49 installed.

Thanks. Mike
screen.jpg
 
I haven't read all the threads so apologies if this has been covered ... The Superpet character rom is different to the normal character rom.... it's a 4k rom with th PET switching to the upper bank when in Superpet mode. You need to burn a Superpet char rom. This can be found on Zimmers.net
 
Yes, this is mentioned in the thread (post #4).

Mike, the cursor is actually in the correct place for the initial 6809 boot screen... 14th line down.

You are not too far away.

As Andy and I have previously stated - do you have the correct character generator ROM installed? Your post #5 states that it is the original 8032 UA3 character generator. Is this still the case?

The CRTC provides a signal "CHR OPTION" that is /CS on a 2K character generator and an extra address line on a 4K character generator. If the CHR OPTION is activated by the 6809 ROM, this will disable any 2K character generator that is fitted.

The cursor may be generated by the 'inverse video' option - which is not dependent upon the character generator itself.

If the character generator is disabled, this would account for the solid ON pixels on the screen irrespective of what character is supposedly displayed in the cell. If the 'inverse' bit is set for the cursor - or it is alternately being set and cleared (based upon the frame timer interrupt), this should cause the cursor to appear to 'flash' even though the pixels from the character generator are all permanently ON.

The text says it all:

1713864903288.png

"The second half..." implies that the signal CHR OPTION is set HIGH (you can check this on the character generator pin to convince yourself). This should (as stated previously) disable any standard 8032 character generator ROM (if it is still fitted). As the SuperPET is a true ASCII machine (as opposed to PETSCII) the lack of the correct character generator is possibly your issue?

Just some thoughts to try and justify what we are observing...

Dave
 
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Based on comments from AndyG and Dave I programmed a TMS2532 with the Superpet character ROM contents. With 6809E and new character ROM the unit booted normally in 6502, and ran perfectly in 6809 mode. Success!

Unfortunately after leaving it powered up for 10-15 minutes, when I returned there was gibberish on the screen and now I cannot get 6502 to boot even with 6809 and U49 removed. I removed the combo board and plugged in the 6502 the 8032 performs normally. It seems now there is a hard failure on the combo board so hopefully it will be easier to scope it to find the problem.

Thanks for your help.

Mike
 
Check the 5 v regulators on the combo board ? Just a quick thought. They can be prone to failure.
 
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