PDP-11/23 PLUS and FDF11 option

From: Jerome Fine <jhfine_at_idirect.com>
Date: Mon Aug 6 13:51:06 2001

>Tony Duell wrote:

> > The FPF11 has jumpers along the bottom which determine which backplane
> > pins it uses for power and ground. These allow it to be plugged into
> > either a Qbus or a Unibus backplane, for use with a pdp11/23 or a
> Actually, +5V and ground are on the same pins on Unibus and Qbus slots.
> The jumpers on the FPF11 determine which pins on the bus will be shorted
> together, thus giving either a Unibus style grant continuity or a Qbus one.

Jerome Fine replies:

While I have not used a Unibus system for a long time (and even less did
I pull boards in and out), your explanation does provide the logical answer.
Thank you.

> I'd like to see you fit one in a Pro350, though :-) (you did say any
> F11-based system). But actually, if you could power it somehow, I think it
> would work with the Pro.

If I used a PRO350 on a regular basis, it certainly would be interesting to
try. Aside from the fact that you might need a longer cable to the socket
that the FP chip normally uses, if you need only power and ground for the
board, that does not seem very difficult. Of course, the overall benefit
might not be worth the trouble since how many of the total instructions
would be faster. So maybe this could be one of your long term projects.
But let us know if you ever try it what happens!!!

Sincerely yours,

Jerome Fine
Received on Mon Aug 06 2001 - 13:51:06 BST