28 Mar
2008
28 Mar
'08
6:21 a.m.
Hi Tony
I agree that the concept of originality is important in what we
do. The system I have is original in the sense that all the parts are
from the right era. However the current configuration
is not that as
stated on the factory label. You could also say that any item with a
date of later than the manufacturing date and not the result of a repair
or upgrade is not original.
Thanks for the tip re Cricklewood I will contact them.
I must say that for the few days it did work I was really pleased with
it. I had got as far as sending a stream of characters out to a screen
at 110 Baud. I had forgotten how few instructions you needed to get it
to do something useful. I actually used to service PDP8's at Harwell
circa 1971. The first type had a large number of small boards with
transistor based logic on them. The other type were as the one I have,
using mainly TTL plus something that needs +3 Volts.
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Tony Duell
Sent: 27 March 2008 22:25
To: cctalk at classiccmp.org
Subject: Re: Looking for a M8330 or a couple of SN74194's
Now I need either a couple of 74194's or an M8330
board.=20
The former being a lot easier to find than the latter, quite apart from
the moral aspect of keeping the machine as original as possible.
I don;t know if they have them, but have you tried Cricklewood
Electronics? They had some 74(LS)95 chips when I needed them to repair
an old HP machine, and seem to be the only place that did.
-tony
28 Mar
28 Mar
10:52 p.m.
Hi Tony
I agree that the concept of originality is important in what we
do. The system I have is original in the sense that all the parts are
from the right era. However the current configuration is not that as
stated on the factory label. You could also say that any item with a
If this is the machine I think it is, I know not only the chap you got it
from, but also the owner before that. IIRC, it originally had a TU56
(single drive versiun, and no I don't mean a TU55) which is currently on
my desk, hooked up to my PDP8/e. And the RX8/e is not original.
If you look at one of the CPU logic boards, you'll see one of the chips
(I forget what) has been replaced. I did that over 10 years ago to cure a
problem with the top 4 data lines in some operation or other. The TU56
was 'payment' for that repair...
date of later than the manufacturing date and not the
result of a repair
or upgrade is not original.
True, and some museums, alas, take it that way, and refuse to instal
replacement parts to keep their machines going, even if said parts are
contemporarty with the machine. Personally, I like all my classics to run.
However, I also like to use as few spares as possible. If your clock
generator was missing, or physically cracked in half, or... then I would
agree you need an M8330 board. But if you can get your old one to run
again, even by using more modern parts (I would have no problems fitting
LS chips if they would work electrically, for example), then I'd rather
keep the spare board for somebody who really did need it.
Thanks for the tip re Cricklewood I will contact them.
They may only have LS or something like that. As I said, I needed some
7495s, a rather oscure shift register chip that I couldn't find anywhere.
They had 74LS95, which worked fine in my HP9820. OK, not original, but at
least I can use the machine again.
-tony
6119
days inactive
6119
days old
1 comments
2 participants
participants (2)
-
ard＠p850ug1.demon.co.uk -
RodSmallwood＠mail.ediconsulting.co.uk