Date   : Thu, 07 Aug 2003 15:21:58 +0100 (BST)
From   : Peter Turnbull <pete@...>
Subject: Re: BBC B issue differences?

On Aug 7, 13:58, Jules Richardson wrote:
> Hi,
>
> is there an easy answer to what the differences are between the
different BBC B
> issue numbers? Just going through my collection and I seem to have
issue 3, 4
> and 7 machines - with 7 being far more common. I don't recall ever
seeing 1 / 2
> / 5 / 6's. (possibly 1 and 2 were model A machines? Certainly my
ICL-built
> early machines are still issue 3's)

There's very little difference between 4 and 7.  The tracks were
re-worked to prvide better power/ground distribution and clean up some
signal lines.  Issue 2 had some bugs, partly corrected in Issue 3, the
rest were fixed in Issue 4.  The service manual gives the details of te
bugs (things like adding a transistor for the printer strobe, capacitor
for the sound, etc).  Issue 1 exists but very few were made (and if the
person who borrowed my Issue 1 and never returned is reading this, I
WANT IT BACK PLEASE!) because it had a lot of problems.  My
understanding is that 5 and 6 were drawn (really only partly drawn) but
never released to production; they were just re-works to improve power
and ground.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York