Date   : Mon, 14 Jul 1997 15:28:32 +0100
From   : Mike_Tomlinson@...
Subject: Re: Master 128 fault - can anyone help?

"1) Master 128 circuit diagrams"

This should be available from Acorn's FTP site:

http://www.acorn.com/ftp/documents/circuits/sprites/Master128/

These are in sprite format tho.  You will need an Arc to print them.

There are GIF format diagrams, but the Master ones seem to be missing.


"2) Master 128 diagnostics disk"

I don't think there are any "official" diagnostics.  I used to use
the Watford Diagnostics.  This will test the Master's SW RAM.

"3) Any suggestions as to what might be wrong......"

There are links to disable one or both banks of SWRAM and allow
the spare rom sockets to be used instead, but the RAM wouldn't have
worked at all if these were set to ROM.


Zul Kahan's suggestion of View copy protecting itself is possible,
but the original poster said he tried other ROMs with similar results.


"P.S. The 64k of main memory seems okay, but the 64k SWR is hosed.
Does anyone know which of the four 41464 ram chips form the
SWR banks?"

>From (shaky) memory, I think ICs 17 and 23 are the SW RAM chips.
The circuit diagram tells you.  You can tell whether you've got the
correct ones, as the machine will run with just the two system RAMs
present.


You could try removing all 4 and fitting sockets, then swapping chips
around until you determine the faulty one(s).

Type *SHADOW OFF and MODE 0 to put the machine into a high res non-shadowed
mode.  If dots or lines appear on the screen, the system memory is faulty
too.


The Master memory was unusually reliable however; it's possible there
is a fault in the memory controller (CF30058, just above the 65c12 IIRC.)

regards,


Mike Tomlinson


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