Date   : Fri, 20 Sep 2013 10:36:09 +0100
From   : bbc@... (Dave Curran)
Subject: Early BBC MOS EPROMs

I've been going through a pile of used EPROMs I got on ebay a while ago and
have found 4 2732 EPROMs labelled 'C', 'D', 'E' and 'F'. It was mainly
27128s in the box, and that was what I was after at the time. I remember
looking at the time to see if there were any marked 'A' and 'B', so I just
assumed they were an incomplete set from something and put them to the back
of the box.

Now I'm after some 2732s I thought I'd check what was on them. The
following string stands out:

 :
 :   (c) 1981 ACORN Computers Limited
 :
 :
 :   BBC Microcomputer Machine Operating System (MOS)
 :
 :
 :   Change record:
 :   032 12-Aug-81 PB     Swop '_'

Above that it says OPT MOS70.

I then twigged that there probably wasn't an A and a B, and the CDEF must
refer to C000-CFFF, D000-DFFF etc. and I remembered reading about early
BBC's having the OS on 4 EPROMs. I think there is a way of arranging the
jumpers to set the board up for this (may just have been the early
issues?). Anyway, I was interested to see if they worked so rather than
work out the jumpers, I combined the 4 images onto a 27128 and put it into
a BBC in place of OS 1.2.

It beeped (but the beep didn't stop) and the screen showed

BBC Computer 32K

No language ROM?_

So I put in back the BASIC ROM and tried again

BBC Computer 32K

BASIC


?_

No response from the keyboard and the beep doesn't stop, so I presume some
of the device addresses or OS entry points might have changed.

Just wondering if there is a copy of this in an archive somewhere or if
anyone is interested. Doesn't seem to be usable on the issue 4 board I
tried it on, but might be of interest to someone?

The ROM ends with

(C) 1981 Acorn Computers Limited.Thanks are extended to the following
people, companies and locations, contributors (among others too numerous to
mention) to the development of the BBC Computer:David Allen,Bob Austin,Ram
Bannerjee,Paul Bond,Allen Boothroyd,Cambridge,Cleartone,John Coll,Computer
Laboratory,Chris Curry,Designers of the 6502,Jeremy Dion,Tim Dobson,Joe
Dunn,Paul Farrell,Ferranti,Steve Furber,Jon Gibbons,Lawrence Hardwick,Dylan
Harris,Hermann Hauser,Hitachi,Andy Hopper,ICL,Martin Jackson,Brian
Jones,Chris Jordan,David King,David Kitson,Paul Kriwaczek,Peter
Miller,Arthur Norman,Glyn Phillips,Mike Prees,John Radcliffe,Peter
Robinson,Richard Russell,Kim Spence-Jones,Graham Tebby,Chris Turner,Adrian
Warner,Wilberforce Road,Roger Wilson,Alan Wright.

Which seems to differ slightly from the message in the OS1.2 ROM:

(C) 1981 Acorn Computers Ltd.Thanks are due to the following contributors
to the development of the BBC Computer (among others too numerous to
mention):- David Allen,Bob Austin,Ram Banerjee,Paul Bond,Allen
Boothroyd,Cambridge,Cleartone,John Coll,John Cox,Andy Cripps,Chris
Curry,6502 designers,Jeremy Dion,Tim Dobson,Joe Dunn,Paul
Farrell,Ferranti,Steve Furber,Jon Gibbons,Andrew Gordon,Lawrence
Hardwick,Dylan Harris,Hermann Hauser,Hitachi,Andy Hopper,ICL,Martin
Jackson,Brian Jones,Chris Jordan,David King,David Kitson,Paul
Kriwaczek,Computer Laboratory,Peter Miller,Arthur Norman,Glyn Phillips,Mike
Prees,John Radcliffe,Wilberforce Road,Peter Robinson,Richard Russell,Kim
Spence-Jones,Graham Tebby,Jon Thackray,Chris Turner,Adrian Warner,Roger
Wilson,Alan Wright.

Thanks,

Dave