CESI VM8128 PDP8-A 128 K MOS?

[Doug Ingraham]

As stated this is a 128k word mos memory board for the 8/a processor.  On
its own it would only present as a 32k board.  To make it work as a 128k
you also need to have a M8416 board which drives the additional address
lines.  And not all 8/a chassis had support for this.  All 4 of my
backplanes have a label indicating KT8A support.  I am guessing that
originally the additional address lines were not connected across the
backplane on the 6th connector.  My card does have some bad bits and one of
these days I will get around to replacing some chips.  This is probably why
I was able to get it not paired with the fancy MMU card.

I have an M8417 but have been unable to find an M8416 at a price I was
willing to pay.  Apparently there are still a few 8/a's with these cards in
service in Genrad testers and that makes the cards still valuable.

There is info on it in the PDP 8/a PDF's on bitsavers.  I think there was a
TSS8 variant that used it as a fast swap but I don't know of anything else
from DEC that supported it.

Best Wishes!



On Fri, Aug 24, 2018 at 5:38 AM, allison via cctalk <cctalk at classiccmp.org>
wrote:

> On 08/24/2018 07:06 AM, Rod G8DGR via cctalk wrote:
> > M8417 MSC8DJ PDP8A 128K MOS
> >
> > Clone of this
> >
> >
> >
> > Sent from Mail for Windows 10
> >
> > From: Paul Anderson via cctalk
> > Sent: 24 August 2018 10:12
> > To: General Discussion: On-Topic and Off-Topic Posts; cctech at vax-11.org
> > Subject: CESI VM8128 PDP8-A 128 K MOS?
> >
> > I have an idea what this might be, but I can't find anything to confirm
> it
> > on line. Can anyone shine some light on it?
> >
> > Thanks, Paul
> >
> its a 128 memory card If memory is right hex width for PDP-8A... The
> last of the omnibus 8s.
> That machine had extended the MMU used in earlier PDP-8 from 3 EMA lines
> to 5.
> Only fits the 8A chassis.
>
> Allison
>



-- 
Doug Ingraham
PDP-8 SN 1175
Assorted 8/a chassis
DECSet 8000 (It is a blue PDP 8/e okay?)