MV-1 bad ram

Address 00000000
Write 5555 Read 7555


If anyone wants to share the Ram address ranges
and locations for the Neo boards...it would be thanks.

lower ranges, 43256 RAM. Upper RAM, a line stuck. Not a RAM, but a pin lifted or shorted somewhere. D2 on the higher order ram. Check pin 12 of each flat pack RAM abnd also check out pro-bp and pro-c0. If there is any board corrosion, that can also cause it, but I would bet on an unsoldered pin 12.