Multiface Two works but will not return to the original running program

[Rabs]

I have a Multiface Two which appears to work in that, when I stop a program the functions work (i.e. tools).

But when I attempt to return to the original running program the CPC crashes/hangs (I get a black screen if running just BASIC and no beep on pressing DEL).

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When I try to set one of the CRTC registers, I do not see the value being stored (I took the idea from Noel's video on the Multiface Clone).

I was expecting to see &1C at &3A87.

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I am guessing that the problem may reside with the PALs. 

Anyone have any hints about what to look at?

Can I take the JED files from the CPC Wiki and create some new GALs to replace the PALs?

Thanks, any help much appreciated.

[Bryce]

I'd try cleaning the expansion pins on both sides first to make sure it's not just a dodgy connection.

Bryce.

[Rabs]

Replaced the right PAL (Orange) and my test now works and return to BASIC works. But only once. If I press stop again nothing happens. Is this expected?

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[Rabs]

I replaced PAL 3 with the PAL/GAL decodes by Jose Leandro. See  CPCWiki Multiface II.

All appeared to work but I could only "stop" once. The second time I pressed "stop" nothing happened until I pressed "reset", which seemed to clear the problem an allow a "stop" again.

So I decided to replace the ROM and use the version by Jose Leandro and this worked and I can now "stop" multiple times.

I compared the ROM by Jose Leandro with the original 0E version from the CPC Wiki and there are differences.


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