Re: IIE SELF-TEST: Which ram is bad? error code

[dempson@actrix.gen.nz (David Empson)]

stephen e buggie <buggie@ben08.unm.edu> wrote:

> I've been give three junked IIe motherboards.  (Mrs. Buggie does not yet
> know it ...

> The third is now enhanced, and this RAM error message appears on the
> self-test screen:
> 
>                  R A M      0 0 0 0 0 0 0 1
> 
> This message clearly states that one of the motherboard eight RAM chips is
> bad, and that it is either the first or last of the eight.   But _which
> one_?

The comments in the IIe firmware listing imply that the bits are listed
in the "normal" order, i.e. most significant on the left, least
significant on the right.  The faulty chip is therefore the one
containing bit 0.  This is UF6 according to the circuit diagram.

> The left-most RAM chip is labeled on the front edge of the m-board as #6,
> and the right-most RAM is #13.

That corresponds to the circuit diagram.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand