Date   : Fri, 03 Dec 2004 20:43:07 -0000
From   : "John & Helen Simpson" <john@...>
Subject: Eprom programming problem

Hi there,

I have been trying to program an Eprom using Angus Duggan's design for
an Eprom programmer (as seen on 8bs and on Angus' own site). Basically
my problem is that the Eprom programmer runs OK, but the resultant Eprom
is not recognised by the BBC.

I think I have worked out what the problem is - I have used a CMOS
27C128 whereas the instructions for the programmer seem to imply that
you have to use a plain 27128. I reckon that the higher programming
voltage might have fried my poor CMOS eprom. Do you think I am on the
right track with this diagnosis, and if so is it still possible to buy
27128s? I think I probably bought the CMOS one because it was the only
type of 128kBit eprom in the catalogue at the time.

Symptoms:

1) When I plug the Eprom (in a cartridge) into the Master and try to
*SRSAVE the relevant bank, the command fails, presumably because the
machine cannot detect any ROM at that position, not even a garbled one.

2) If I try to use the Eprom programmer software to save the contents of
the Eprom, it reports an Eprom programmer error at a location above
&A000. Yet the Eprom was (when new) verified OK and written to
successfully.

This is just a messing about in my spare time sort of project but I'd be
grateful for some ideas.

Thanks

--
John