Malfunctioning VT240 - help please

Tony Duell ard.p850ug1 at
Mon Jun 15 10:41:58 CDT 2020

> My fear is that one of the PALs has altered itself from tin-whisker
> migration (fuse regrowth) :(

I've finally looked at the printset for the VT240 and I must be
missing something....

The only PALs I can find are the 'logic units' in the  video memory
updating circuitry. That circuitry is pretty much the same as .... the
Rainbow colour graphics board and I suspect the PAL logic is much the
same too. I have the Rainbow's PAL equations if you need them but I
doubt that's the problem.


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