Quote:
Originally Posted by Mark1960
Are any of the ICs on the board in sockets, or any other signs of previous repair attempts?
Its quite promising as it looks like the 6502 is running and just the display circuits need attention, the keyboard is probably a separate issue.
It seems the display is showing 0 where it should show space, that would only be a single bit position wrong. 0x30 for 0 instead of 0x20 for space. Also probably explains display of 333instead of *** in the boot screen.
It could be either the circuit reading video ram to the character generator, the character generator itself or one of the 74ls244 buffers, possibly writing incorrect data to video memory.
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Hi
Yes, some of the ICs were in sockets, I removed them before washing the board.
I attach a picture before I removed everything
A fair few of the ic have very tarnished looking pins/legs