5 Dec
2013
5 Dec
'13
3:35 a.m.
They do crop up on ebay from time to time , but not cheep, I would have
bought the last one I saw if the carraige from the states had not been
horendus. Some where on the web Im sure I did see someone who did a self
build but cant have bookmarked it as now cant find it.
Dave
----- Original Message -----
From: <anders at abc80.net>
To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org>
Sent: Wednesday, December 04, 2013 8:00 PM
Subject: Re: [Fwd: Restoration of a PDP-8a]
1. I believe
you should look at page 602 of the PDP8/A users manual:
http://bitsavers.trailing-edge.com/pdf/dec/pdp8/pdp8a/EK-8A002-MM-02_PDP8A_…
That seams to be right! Thank you.
2. Maybe. However if your chassis is set up for
remote power control
you
need to short pins 1 and 3 of the 3 pin control cable connector. Then
the
power should be controlled by the power switch on the limited panel.
However, your model (8A420-CN) is originally set for 240VAC (see page 34
of
http://bitsavers.trailing-edge.com/pdf/dec/modules/modulesAndOptions/Option…);
you might have to adapt it to 120.
It might be set up for remote power control. Didn't know about this. I'll
see if I can find anything that can confirm this. I don't have the rack
and the drives home yet, but I'll have a look this weekend. I know that
the computer is set up for 230V, which is good since I live in Sweden and
have 230V power system.
3. G8019 doesn't show up on the price list;
don't know what that is.
On page 60 in
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8a/PDP8A_Schem…
the "Power distribution board control" is described. The drawing has
number G8019-0-1.
Good luck bringing up a 8/A without the
programmers console. Without it
you can't toggle in anything; you're limited to whatever boot devices are
programmed into the boot roms on the M8317.
Thanks, I'll know that it will be hard, I have a programmers console on my
wish list for this Christmas...
/Anders
Marc
On Wed, Dec 4, 2013 at 3:46 AM, <anders at abc80.net> wrote:
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.2247 / Virus Database: 3658/6393 - Release Date: 12/05/13
Hi,
I have started restoration of a PDP-8a model 8A420-CN. I doesn't have
any
schematics for this machine and I have searched internet for sources
without any luck. The sets on
http://bitsavers.trailing-edge.com/pdf/dec/pdp8/pdp8a does not include
my
version.
My machine came with 16K*12bits core memory, 20 slot backplane and only
the "Limited function board" frontpanel (don't now if this machine ever
had the "Programmer's console").
This is how my "Power distribution board" looks like:
http://www.abc80.net/docs/pdp8/pdp8a/DSC_2118.JPG
Some questions:
1. Is there anybody that could help me with schematics on this machine?
Scans are preferred, but I can pay for paper prints. I'm especially
looking for a diagram that matches the "power distribution board" that I
got.
2. If I plug in the machine with only the regulator boards (2xG8018) and
the limited function board in it, should the lights and fans come to
life?
3. I suspect that my model shouldn't have "Power distribution board
control", G8019 since my "Power distribution board" misses the connector
for this board. Can that be correct?
Any help is appreciated. PPD-8a is new to me, but I have some knowledge
in
the PDP-8 architecture since I restored a PDP-8/L that was in really bad
shape.
/Anders
