11/70 board set on e-bay. . .

Henk Gooijen henk.gooijen at hotmail.com
Tue Jan 15 14:13:25 CST 2008

> To: cctalk at classiccmp.org
> From: legalize at xmission.com
> Date: Mon, 14 Jan 2008 20:02:48 -0700
> Subject: Re: 11/70 board set on e-bay. . . 
> In article 478C1B0E.8090407 at shiresoft.com,
> Guy Sotomayor <ggs at shiresoft.com> writes:
> > The 11/70 CPU is *not* a unibus backplane. It is a *very* large 
> > backplane that fills an entire BA11F.
> Interesting, I just assumed it was unibus. Is the /70 the only PDP-11
> that has a custom backplane? I thought the PDP-11 family had standard
> backplanes: unibus and Q-bus.
> -- 
> "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
> http://www.xmission.com/~legalize/book/download/index.html
As far as I know from my collection (I have a few UNIBUS machines)
I can say the following.
The PDP-11/10 and PDP-11/05 (OEM version of the /10) have 4 different
backplanes, the difference is in the memory and some peripherals supported.
I don't have the /20 (and OEM /15) and don't have the /24.
The /04 and the /34 (and 34/A and /34C) have a 9-slot backplane of which
the first slots are CPU module specific (backplane is the DD11-PK).
The 11/40 (and OEM /35) have the same backplane KD11-A, again CPU specific,
here 5 slots are for the basic CPU, and 3 slots are dedicated for CIS, FIS and MMU.
The /44 has a 14-slot backplane (KD11-Z) and almost all slots are dedicated
to specific boards. A few slots are for memory.
The /45 and /55 are new in my collection and I have not yet had time to look
at them. I suspect that, together with the /50, these 3 share the same
backplane (KD11-B or KD11-C), but as said, I can be wrong.
The PDP-11/60 backplane (KD11-K) is also 14-slot, and here all slots are
dedicated to the CPU modules.
The 11/70 backplane, as just written, is physical two parts of each 22 slots,
but they are heavily interconnected by wire wrapped wires. Consider the in total
44 slots backplane unseparable.
The 11/84 (and /94) are a bit "weird", in that the backplane starts as a sort-of
QBUS backplane, and after the "unibus-bridge" continues as a UNIBUS backplane.
Several months ago there has been a very good discussion about this backplane!
For most of these backplanes you can take a peek on my website, in the folder
called "CPU information"  under each PDP-11/xx folder. Sorry, the 11/45 folder
is "under construction", and the 11/55 folder is still "off-line" ...
- Henk.

More information about the cctalk mailing list