Post by happycodingzx in Pacman RX comments

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sorry, my mistake, I read your post too quickly and thought you meant +2. Could you try the following for me:
PRINT PEEK 2815 : PRINT PEEK 2816
And tell me the results. keyboard shortcut for peek is caps+symbolshift + O
If you don't get 34 and128 then you have a non-standard ROM which could be the cause of the issue. If not, I'm somewhat stumped!

thanks!

shazeal213 days ago

I get 34,128. all the main board components are original, I did try it with a vLA82 ULA chip as well and it did the same thing. I will be building a DIY issue 3b soon so will try on that, to see if that works.

happycodingzx212 days ago

hmmm... ok. I have no idea what the issue is then. Aside from the digital version which has been tested extensively on various emulators, the game has been released as a physical tape so there are quite a few people out there playing on real hardware and I've never had an issue. It's very odd.

shazeal132 days ago

So I built a Spectrum Issue 3b from scratch using all new parts, it works perfectly. But this game crashes in exactly the same way as on the original Issue 2. So the only thing in common hardware wise is the original (1980s) Ram Turbo Joystick interface... unplug that and the game works fine. Maybe some bug in the joystick controller?

happycodingzx131 days ago

right, I think I understand the issue - I'm afraid the game is not compatible with certain old joystick interfaces which don't actually follow the correct protocols and cause an issue with the interrupt. In the 80s, coders would create a 257 byte lookup table to account for this issue as it was a fairly common issue, but this is the first time I've had anyone have this issue.

shazeal131 days ago

Cheers for the explanation. Will have to pickup a new interface, thanks for the help 🤘

happycodingzx131 days ago

no problem - a modern interface that gives you some extras as well as a joystick would be a good call. One recommendation would be one that includes an AY chip, as the game will detect this and give you AY music and sounds, even on the 48k model if available.

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