3 Apr
2013
3 Apr
'13
7:21 p.m.
I'm looking at upgrading a pdp11/73 in a pdp11/23plus box to an 11/83. Is there a
simple multimeter test I can do on a qbus slot to determine if it is Q/Q -- which i
understand can be serpentine, or Q/CD, which are PMI capable for the 11/83 CPU.
Thanks.
4 Apr
4 Apr
8:51 a.m.
On Apr 3, 2013, at 19:21, Roe Peterson <roe at liveblockauctions.com> wrote:
I'm looking at upgrading a pdp11/73 in a pdp11/23plus box to an 11/83. Is there a
simple multimeter test I can do on a qbus slot to determine if it is Q/Q -- which i
understand can be serpentine, or Q/CD, which are PMI capable for the 11/83 CPU.
Easier: find the model number of your backplane here:
http://www.dunnington.u-net.com/public/PDP-11/QBus_chassis
If you have a BA23 or BA11-S chassis,
you ought to be set.
- Dave
4:15 p.m.
On 04/04/2013 13:51, David Riley wrote:
Indeed, or as Jerome suggested, looking at the configuration of the
cards may give you a clue. So would the type of box: if it's a 3U-high
(5.25") grey-fronted-metal-panel rack-mount box with three toggle
switches, it's a BA11-N or BA11-S, which have straight backplanes (and
are all QQ-CD), if it's a small tabletop box or a 2U (3.5") it's a
BA11-V (tabletop) or BA11-M (2U) which have serpentine backplanes, and
if it's a floor-standing microPDP-11 (or microVAX) box or a chassis with
four or six pushbuttons on the front, it's a BA23 box which is QQ-CD in
the top slots and serpentine below.
Or count the card slots. All 9-slot backplanes are straight. 8-slot
and 13-slot are mixed (for microPDP-11 and microVAX). Anything else is
serpentine.
BA11-M and BA11-V boxes are relatively uncommon. If it's a BA11-N,
although the backplane is 18-bit, it's very easy to upgrade to 22-bit.
On Apr 3, 2013, at 19:21, Roe Peterson <roe at
liveblockauctions.com>
wrote:
>
> I'm looking at upgrading a pdp11/73 in a pdp11/23plus box to an
> 11/83. Is there a simple multimeter test I can do on a qbus slot
> to determine if it is Q/Q
[ ... ]
or Q/CD, which
are PMI capable for the 11/83 CPU.
Easier: find the model number of your backplane here:
http://www.dunnington.u-net.com/public/PDP-11/QBus_chassis
If you have a BA23 or BA11-S chassis, you ought to be set. > -- which I understand can be serpentine,
All Q-Q backplanes are serpentine, and all straight backplanes are
QQ-CD. The only odd one is the hex-high DDV11-B, which is a serpentine
backplane in the ABCD positions and not bussed at all (except for power
in the standard contact positions) in EF - it's meant for custom wiring.
Of course we're assuming it's a DEC box with a DEC backplane. A
Plessey backplane, for example, might be different, but you'd probably
know if it was non-DEC, because it's pretty rare to find DEC's dark
green connectors on anything non-DEC. Plessey and GEC ones, again for
example, are white.
--
Pete Peter Turnbull
Network Manager
University of York
5:06 p.m.
On 4 April 2013 16:15, Pete Turnbull <pete at dunnington.plus.com> wrote:
Or count the card slots. All 9-slot backplanes are
straight. 8-slot
and 13-slot are mixed (for microPDP-11 and microVAX). Anything else is
serpentine.
That's not correct. The H9273-A backplane (quad wide, nine slot long, QQ/CD
18-bit) of the BA11-N box can be replaced with an H9275-A backplane (quad
wide, nine slot long, QQ/QQ 22-bit) which is a serpentine backplane
specifically designed to be put inside of a BA11-N box (for OEM use). I
should know; I have an H9275-A backplane! (I don't have a BA11-N box to use
it in though...)
The H9276-A backplane of the BA11-S is a 22-bit wide QQ/CD straight
backplane though.
The "odd" DDV11 backplane is also a 9 slot backplane, but it is 18-bit, has
the AB/CD slots as standard serpentine QBUS and the EF slots as just power
and grounds. (For shits and giggles, rewire them as CD slots and have a
QQ/QQ/CD backplane.)
Also of note, the BA11-M box with H9720 is an 18-bit quad-wide serpentine
backplane of four slots length; which can also have an H9270-Q backplane
installed which is the same size but 22-bit. The BA11-V is always 18-bit
(don't know if you can easily upgrade it to 22-bit) but only dual wide and
four slots long if I remember (so, the serpentine moniker is incorrect).
Only other QBUS backplanes of note are the H9281 series, where again the
serpentine/straight+CD distinction is a non-issue since those are all
dual-wide backplanes of various lengths. (And there's the H9278 of the BA23
which we'll ignore as you probably won't see one of those floating around
"naked" without its box.)
Cheers,
Christian
4:19 p.m.
On Apr 4, 2013, at 7:01 AM, David Riley <fraveydank at gmail.com> wrote:
On Apr 3, 2013, at 19:21, Roe Peterson <roe at
liveblockauctions.com> wrote:
Thanks. It's a BA11-S, the H7861 power supply is a dead giveaway. I'll install
the 83 after work. AKAIK, the memory cards actually get installed _above_ the CPU, with
the unibus stuff below.
I'm looking at upgrading a pdp11/73 in a pdp11/23plus box to an 11/83. Is there a
simple multimeter test I can do on a qbus slot to determine if it is Q/Q -- which i
understand can be serpentine, or Q/CD, which are PMI capable for the 11/83 CPU.
Easier: find the model number of your backplane here:
http://www.dunnington.u-net.com/public/PDP-11/QBus_chassis
If you have a BA23 or BA11-S chassis, you ought to be set.
- Dave
8:55 a.m.
Roe Peterson wrote:
I'm looking at upgrading a pdp11/73 in a
pdp11/23plus box to an 11/83. Is there a simple multimeter test I can do on a qbus slot
to determine if it is Q/Q -- which i understand can be serpentine, or Q/CD, which are PMI
capable for the 11/83 CPU.
I hope that Allison is available to determine if I am suggesting a
possibility that might damage a board of the backplane.
I doubt that is a possibility, but just in case, can anyone else please
comment as well.
A BA23 box is wired with the top 3 slots as Q/CD and the lower
5 slots as Q22 / Q22. If a backplane slot is wired as Q / CD,
then that slot can hold ONLY a single board, either dual OR quad,
on the left side of the slot. If a backplane slot is wired as Q/Q,
then either one quad board or two dual boards are used. The order
of the boards in a BA23 is:
!A 1
2A 2
3A 3
4A / 4B 4 / 5
5A / 5B 7 / 6
6A / 6B 8 / 9
etc.
Depending on if your PDP-11/73 uses any or none of the "B" portion
of the backplane when a dual board is present, you already know if
any of the backplane is Q/Q.
Since you have not provided a list of the boards and the location of
each board, I can not comment further.
However, you can always place a dual board in an "A" slot and leave
"B" portion empty. If that slot is Q/Q, then the bus grant will be broken
and any boards beyond that location in the chain will not interrupt.
If I have not explained the situation carefully enough, please ask more
questions.
Do you already have the M8190-AE and the PMI memory boards?
If you do, then you may want to compare the speed difference. When
I performed a similar benchmark under RT-11, I found that the PDP-11/83
was about 33% faster than the PDP-11/73. About 20% was due to using
the PMI memory (which usually works with the PDP-11/73 boards as well)
and about 13% was due to the faster crystal on the M8190-AE board.
If you have any more questions, please ask.
Jerome Fine
4128
days inactive
4129
days old
5 comments
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participants (5)
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captainkirk359＠gmail.com -
fraveydank＠gmail.com -
jhfinedp3k＠compsys.to -
pete＠dunnington.plus.com -
roe＠liveblockauctions.com