//c RAM problems

[gospodin@indigo.ie (Vincent Quinn)]

Out of my four //c motherboards, three have problems :-(

The first one has a bad IWM, so I'm prepared to sacrifice it to repair the
other two, both of which have bad auxiliary RAM. But can anyone help me
identify exactly which chips on the boards need to be replaced?

Board one is a ROM 0. It appears OK but the 80-column display throws a few
rogue characters ($s and 0s) up on the screen. The self-test returns the
following message:

*RAM 0 0 0 0 0 1 0 0

Running diagnostic programs on it gives the following:

Auxiliary memory needs repair:
Error 04 at 010B64

Finally, FASTCOPY.SYSTEM gives another confirmation: "A memory failure has
occurred...The failure occurred in auxiliary RAM".

Board two is a ROM 255. The 80-column display gives real gibberish - many
of the characters are displaying as something else (no, it's not because
the Dvorak switch is down). Of course, there is no self test; but running
the same diagnostic as above gives me:

Auxiliary memory needs repair:
Error 08 at 010800

Is there anything else I can do to narrow it down? Also, am I right in my
assumption that the chips marked MRD0-MRD7 are the main 64K of RAM and
those marked ARD0-ARD7 are the auxiliary 64K?

Thanks

Vincent Quinn