Qbus Backplanes

From: vance_at_neurotica.com <(vance_at_neurotica.com)>
Date: Fri Jun 6 14:07:31 2003

And what do you do if you want to use a QQQQ-only processor in a QQCD
backplane? Put it in the QQQQ-end?

Peace... Sridhar

On Thu, 5 Jun 2003, Peter Turnbull wrote:

> Yes, a normal BA11-N is Q-CD. So is a BA11-S.
>
> If you can read the H92xx number off the backplane (it's often visible
> without too much effort, for example it's on the top of a BA11-M/N/S
> backplane) you can look that up to see if it's straight (Q-CD),
> serpentine (Q-Q) or mixed.
>
> The following is not exhaustive, but includes the common ones:
>
> PDP-11/03 BA11-M H9270 18-bit 4 x Q-Q
> PDP-11/23 BA11-N H9273 18-bit 9 x Q-CD
> H9275 22-bit 9 x Q-Q
> PDP-11/23+ BA11-S H9276 22-bit 9 x Q-CD
> microPDP-11 BA23 H9278 22-bit 3 x Q-CD, 5 x Q-Q
> H9281 18-bit various sizes, only two slots
> (AB)
> microPDP-11 BA123 54-17507
> or 70-22019 22-bit 4 x Q-CD, 8 x Q-Q, 1 x non-bus
> DDV11 18-bit 9 x Q-Q, slots EF are separate
>
> Q-Q backplanes are usually referred to as serpentine (or sometimes as
> zig-zag), Q-CD as straight. Serpentine slot order goes like this:
>
> slot 1 ----> slot 2
> |
> V
> slot 4 <---- slot 3
> |
> V
> slot 5 ----> slot 6
>
> etc
>
> Some of the backplanes have optional jumpers to enable/disable LTC
> interrupt, or for termination. Many carry the SRUN_L signal only on
> row 1. Beware of such differences when changing backplanes or linking
> two together. The DDV11 is unusual in being hex-height instead of
> quad-height; the extra slots are nor bussed, except for +5,V, 0V, and
> -12V, but may carry odd voltages, depending on which OEM or
> experimenter last used it!
>
> There's a rumour that the first 3/4 slots in a BA23/123 are special and
> you can't use them for anything except memory or processor; that's
> rubbish, they're normal Q22-CD slots and you can put anything that's
> Q-CD compatible in them, so long as it's after the processor. What
> *is* special is the range of PMI memory boards; if you put them in
> *front* of a KDJ11-B they use the CD interconnect for the Private
> Memory Interface
> but if you put them *after* the CPU they use the Q-Bus like all other
> memory boards.
>
> --
> Pete Peter Turnbull
> Network Manager
> University of York
Received on Fri Jun 06 2003 - 14:07:31 BST