Q-Bus Backplanes

From: Jerome Fine <jhfine_at_idirect.com>
Date: Fri Aug 14 13:50:07 1998

>Zane H. Healy wrote:

> I spent part of the morning troubleshooting my BA123, turns out that I
> didn't have a blown powersupply <whew>, instead I had managed to short the
> power plug that goes to the TK-50, got that fixed, and it powers up just
> fine. So I then pulled out the MicroVAX II CPU, memory, and some other
> boards, and turned it into a PDP-11/23 :^)
>
> However, I'm finding myself fighting the path that 'snakes' through the
> backplane. Would someone be kind enough to explain it to me? I wish DEC
> had done like SMS did and print it on the case! It's real easy to add and
> remove Q-Bus cards from my SMS-1000's. I'm interested in both the BA23 and
> BA123 backplanes.

Jerome Fine replies:

Has anyone helped in this request? I believe that the following is true:
BA23: First 3 slots are ABCD
            Next 5 slots are ABAB or Q22
In short, you can place only one board in the first 3 slots. If the
board is a dual, you loose the other half. The last five slots are
able to use either a quad or 2 duals. The bus grant loop is serpentine.
1A, 2A, 3A, 4A, 4C, 5C, 5A, 6A, 6C, 7C, 7A, 8A, 8C.
1 ->
2 ->
3 ->
4 -> ->
5 <- <-
6 -> ->
7 <- <-
8 -> ->

The BA123 is identical EXCEPT that slots 1,2 3,4 are all ABCD.
If you want the loop diagram for the Ba123, please respond.

Which operating system do you use on the PDP-11? If it
is RT-11, I would like to keep in touch. I notice that you
have not responded to my e-mail of Monday. If there is
no further response, I will just assume that you are not very
interested in RT-11.

For anyone else (Allison??) who is interested in RT-11
software, a response would be appreciated. I think
I understand that the hardware is the most important
aspect to most of the individuals on this list. I am one
of the exceptions in that the software is the most
important with the hardware being a close second
until a few months ago when it became possible to
run PDP-11 programs on a PC, in particular RT-11
programs and the operating system plus all modules.

One day I even booted a TU-58 from 1978 with
a tape cartridge holding files from a 1978 version
of the RT-11 operation system (V3.0B). While
the TU-58 was connected to a COM port on the
PC which was running an emulator program which
allowed the PC to look like a PDP-11 to the
TU-58, it was still quite a thrill to be able to boot
the 20 year old TU-58 with 20 year old software.
Is there anyone else also interested in RT-11
software?

Sincerely yours,

Jerome Fine
RT-11/TSX-PLUS User/Addict
Year 2000 Solutions for Legacy RT-11 Applications
(Sources not always required)
Received on Fri Aug 14 1998 - 13:50:07 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:30:44 BST