uVAX II Memory Board

From: Jerome Fine <jhfine_at_idirect.com>
Date: Fri Feb 2 20:54:14 2001

>Dave McGuire wrote:

> >On February 2, Jerome Fine wrote:
> > I have an interesting question. Can this board be used as additional ram
> > in a PDP-11? If so, how might it be done?
> > I have a Qbus Memory board that must be from a uVAX II - M7609-AP
> > with 288 (I hope I counted correctly) memory chips
> > 4256L-15 8726255
> > A 21-22422-42 R
> > with the standard male 50 pin header at the top to be connected to a uVAX CPU.
> > If my arithmetic is normal, does this make it an 8 MByte memory?
> It's an 8mb board, yes. And no, it won't work on a pdp11...the PMI
> (Private Memory Interconnect) connector at the top of the board is how
> it talks to the MicroVAX-II CPU, while [most] qbus pdp11 systems talk
> to their memory via Qbus.

Jerome Fine replies:

I know that it is impossible to just use the uVAX II memory as is. I just
thought it might be possible that someone has put together an inexpensive

Maybe someone could use the parts from a uVAX II? If I make enough
dumb suggestions, possibly one might be feasible.

As for the PDP-11 talking to the memory over the Qbus, even the 11/83
does that via the CD interconnect - as far as I know. Whereas the PMI
(if that is indeed the correct terminology) for the uVAX II uses a cable
over the top, for the 11/83 the use of PMI does not require a cable, just
the correct placement of the PMI memory on top of the CPU - on the
component side.

> > I don't expect that anyone will want it, but if so, can I swap it for a regular
> > PDP-11 Qbus memory of 4 MBytes?
> I doubt you'll have much luck with this idea...MicroVAX-II memory
> boards are all over the place, while 4mb Qbus pdp11 memory bards are
> getting hard to find.
> Sorry if I busted your bubble...

No bubble to burst. Actually, most of the time, I use the PC hardware to
run my PDP-11 programs, so the real PDP-11 hardware is now the
backup system. In any case, I thought I might dream - no point in not

Sincerely yours,

Jerome Fine
Received on Fri Feb 02 2001 - 20:54:14 GMT

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