Date : Thu, 25 Feb 2016 00:11:18 -0000
From : blip@... (John)
Subject: Acorn PET and FIT boards
Thanks Pete
Entering a more specific search for P.E.T. using your email, I found these
images:
http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/Acorn_PET.html
It does seem similar to the signature analyser that I posted about later?
(although more specific with the 6502 clip etc. of course).
I'd be interested in your take on my proposal for building an application
(HTML based) that could inform users on carrying out their own repairs.
It seems most repairs do involve getting down and dirty with Oscilloscopes
and the like, but I'd be interested to hear points of view on how useful an
interactive guide could be in helping basic users in saving some BBC
computers (or any computers really) from the skip.
Also, cheap sources of test equipment, not least because I have two to fix
myself!
Kind regards
John Terry
-----Original Message-----
From: bbc-micro-bounces+blip=blipit.com@...
[mailto:bbc-micro-bounces+blip=blipit.com@...] On Behalf Of
Pete Turnbull
Sent: Wednesday, February 24, 2016 11:34 PM
To: bbc-micro@...
Subject: Re: [BBC-Micro] Acorn PET and FIT boards
On 24/02/2016 22:59, John wrote:
> I've never seen these, so forgive a potentially silly question - Acorn
> PET and FIT testing boards - worth having, and if so has anyone tried
> to replicate their function using modern components?
>
> Are they any kind of substitute for, say, an Oscilloscope or similar
> test equipment? Or are they just giving yes/no answers to inform
> quality control?
The FIT - Final Inspection Tester - is basically just for quality control.
With the FITest program (on tape, disk or RFS from another
Beeb) it checks most of the functionality of a Beeb (A or B) but it's not
really a diagnostic aid, it just tells you if everything works (or not). It
won't work at all unless most of the machine is working. When I ran an
Acorn Approved Service Centre we found a small number of times it passed a
machine that wasn't absolutely OK, but not many. I still have mine and use
it occasionally. It's a circuit board about 10cm x 26cm with
connectors/cables for most of the I/O ports.
The PET - Progressive Establishment Tester - is a more complex animal on a
circuit board about twice the size of a FIT. It too has lots of connectors,
including a clip that fits over the 6502, and some other internal s well as
external connections. The theory is that it runs on-board diagnostics,
testing the CPU, then memory, then various functional areas, not relying any
part of the machine until that part has been tested. It has a couple of
7-segment displays for the test/fault codes. It's quite useful, but we
found a scope and logic probe often quicker, and we also had some simple
diagnostics in EPROM on a carrier with a BCD switch to select the test(s) we
wanted - many from examples in one of the service manuals plus some I wrote
- which we substituted for the MOS. I didn't keep our PET; I think one of
my staff got it.
--
Pete
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