3 Dec
1999
3 Dec
'99
6:45 a.m.
These 16K boards use 2147's don't they? Does
your diagnostic (whatever it
Likely it uses 2114s (1kx4).
is) tell you which bit is failing? If it can't
read the bits, perhaps it's
a (1) a failed decoder or (2) it's a failed data bus buffer, or (3) it's a
roached address buffer. The only apparent alternative would be a failed
RAM. It does smack of a failed on-board decoder, however, since only the
one 4K block is failing. If you can't read/write even a single bit in that
4K block of RAM, it's undoubedly a buffer or a decoder. If only one bit
fails, it's probably not a decoder, but then the RAM itself is suspect.
I don't ahve prints for those but memory says it's one of those that
allows block DESELECTs via switches or jumpers. That means the ram could
be good just not enabled.
Allison