Date   : Thu, 27 Oct 2005 08:00:34 +0100 (BST)
From   : Pete Turnbull <pete@...>
Subject: Re: Guess age from serial number?

On Oct 27 2005,  5:19, Jules Richardson wrote:

> Did model B serial numbers carry on from where model A ones left off,
or
> were the models sufficiently seperate to Acorn to warrant a seperate
run
> of serials? (i.e. there's a #1 model A out there *and* a #1 model B)

No they were interleaved.  The first part of the serial number gives
the product code and the rest is the actual serial part, so for example
there might be a batch of As, then Bs, then BDs, then Bs, then BDEs,
etc.  They were all BBC Microcomputers though, so there would be one
run of serial numbers through that lot of production.

Acorn used to have a database that matched batches of serial numbers to
manufacturing dates.  There was no duplicaton of numbers.

> > 001013 might be old enough to be Issue 1.  If not, it's certainly
no
> > newer than Issue 2.  Is the serial number sticker an orange ICL one
> > (that would be Issue 2) or a plain white one (could be Issue 1 or
2)?
>
> I think the lowest I have is around 3300, and that's an ICL machine
with
> issue 2 board. Bloody nasty build quality! :) So yep, deffo an issue
1
> or 2 board in the one Kris has...

If it's orange, it's an ICL.  And they were horrible, I'd say the
nastiest boards ever used, Issue 1 included.  They only built one
production run because Acorn never used them after that.  Those white
IC sockets are the second-worst I've ever seen.  If you shake the PCB
liklely some ICs will fall out.  Many ICL machines arrived not working
because of loose chips.

ICL also thought they'd "improve" the clock circuit.  Those of you
who've looked inside a normal Beeb, or at the circuit diagram, will
have seen a small trimmer capacitor used to adjust the precise
frequency of the colour burst signal used for the PAL video.  Well, ICL
discovered that the processor clock was also divided down and used for
time-of-day-clock interrupts, and so they decided it would be better if
that too could be tweaked so that it didn't drift too much.
 Unfortunately the bodge they fitted to support an extra trimmer
capacitor on the main crystal connects said trimmer in such a way as to
ensure it has zero effect on the frequency generated.  Idiots.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York