ClassicHasClass
Veteran Member
Was programming my briefcase KIM-1 last night when the program suddenly went awry. After trying to eliminate other causes, it turns out that the memory range from $280 to $29f suddenly had its upper six bits get stuck at zero.
It's only this range, however. $0080, $0180 and $0380 are normal, as is everything else in $0200. The RIOT RAM at $1780 is also normal, and the same fault is repeated at $2280, $4280, etc., as one would expect from the KIM's default 8K memory decoding. There are no cards connected.
Feels like a marginal component went bang but the fault seems unusually specific. Anyone got a guess? I thought about bad RAM, but it seems very weird it would be six at once, and limited to that specific range. The fault is also weird in that it's "aligned." Unfortunately everything on this Rev D board is soldered, so I'd prefer not to go mucking around on the board without a good idea where to start mucking around.
It's only this range, however. $0080, $0180 and $0380 are normal, as is everything else in $0200. The RIOT RAM at $1780 is also normal, and the same fault is repeated at $2280, $4280, etc., as one would expect from the KIM's default 8K memory decoding. There are no cards connected.
Feels like a marginal component went bang but the fault seems unusually specific. Anyone got a guess? I thought about bad RAM, but it seems very weird it would be six at once, and limited to that specific range. The fault is also weird in that it's "aligned." Unfortunately everything on this Rev D board is soldered, so I'd prefer not to go mucking around on the board without a good idea where to start mucking around.