HELP with PDP-11/23

I just acquired a PDP-11/23.

I got it for nostolgic reasons. It was the first computer I used (in high
school) and I grew very fond of it. When I saw the chance to get one, I
grabbed it.

But when I used it in the 70/80s, it was always through a terminal. The
computer itself was in the computer room and rarely seen, let alone
touched.

I literally do not know how to turn this thing on!

I have some books, but nothing introductive. They all seem to assume that
I have read all the other books :-)

I'm a quick learner, but I'm going to have to ask a lot of stupid
questions for now. If this isn't the place to ask, perhaps someone could
point me there.

To get things started, here's sampler of stupid questions:

1. It appears to be a 3U rack-mount drawer. No drives or anything (yet). I
hear it's a PDP-11/23. How can I tell for sure.

2. I have 6 half-size boards and 3 full-size boards. Is there a reference
to find out what they are?

3. All the boards came out in shipping. Where can I look for information
on where they should go.

4. The computer seems to slide freely in a black housing. Is that right?

5. I havn't plugged it in yet. Once I do, how do I turn it on. Better yet,
what introductory references might answer this question.

6. I have no disk drive, no tape drive, no storage other than (presumably)
RAM. I have what I believe to be a four-port serial card. What could I
make this thing do? Anything with a prompt would overjoy me at this point.

William Korvine

William Korvine wrote:[color=blue]
> 5. I havn't plugged it in yet. Once I do, how do I turn it on.[/color]

I would really, really recommend that you get someone
with experience in restoring PDP-11s to check it out and
set it up for you. Powering up when there is a problem
can destroy a lot of components!

On Thu, 14 Apr 2005, William Korvine wrote:
[color=blue]
> 2. I have 6 half-size boards and 3 full-size boards. Is there a
> reference to find out what they are?[/color]

[url]http://world.std.com/~mbg/pdp11-field-guide.txt[/url]
(Thanks, Megan)

This version is dated July 2002.
[color=blue]
> 3. All the boards came out in shipping. Where can I look for
> information on where they should go.[/color]

Don't know. [url]http://www.bitsavers.org/[/url] is a good place to start.
[color=blue]
> 4. The computer seems to slide freely in a black housing. Is that
> right?[/color]

Probably.
[color=blue]
> 6. I have no disk drive, no tape drive, no storage other than
> (presumably) RAM. I have what I believe to be a four-port serial
> card. What could I make this thing do? Anything with a prompt would
> overjoy me at this point.[/color]

I don't recall whether the system console would be on the four port
serial card, or a separate interface.

At any rate, when you find the system console port you will be able to
talk to the boot program, do a few (very!) simple diagnostics, and
drop into console ODT. In ODT you will be able to load values into
memory, examine them, and execute them. Load 014747 into location
10000 and then start executing at 10000. This will fill memory
down-wards from 10000 with 014747.

Have fun.


--

Rob Brown b r o w n a t g m c l d o t c o m
G. Michaels Consulting Ltd. (866)438-2101 (voice) toll free!
Edmonton (780)438-9343 (voice)
(780)437-3367 (FAX)
[url]http://gmcl.com/[/url]

William Korvine wrote:
[color=blue]
> I just acquired a PDP-11/23.
>
> I got it for nostolgic reasons. It was the first computer I used (in
> high school) and I grew very fond of it. When I saw the chance to get
> one, I grabbed it.
>
> But when I used it in the 70/80s, it was always through a terminal.
> The computer itself was in the computer room and rarely seen, let
> alone touched.
>
> I literally do not know how to turn this thing on!
>
> I have some books, but nothing introductive. They all seem to assume
> that I have read all the other books :-)
>
> I'm a quick learner, but I'm going to have to ask a lot of stupid
> questions for now. If this isn't the place to ask, perhaps someone
> could point me there.
>
> To get things started, here's sampler of stupid questions:
>
> 1. It appears to be a 3U rack-mount drawer. No drives or anything
> (yet). I hear it's a PDP-11/23. How can I tell for sure.
>
> 2. I have 6 half-size boards and 3 full-size boards. Is there a
> reference to find out what they are?
>
> 3. All the boards came out in shipping. Where can I look for
> information on where they should go.
>
> 4. The computer seems to slide freely in a black housing. Is that
> right?
>
> 5. I havn't plugged it in yet. Once I do, how do I turn it on. Better
> yet, what introductory references might answer this question.
>
> 6. I have no disk drive, no tape drive, no storage other than
> (presumably) RAM. I have what I believe to be a four-port serial
> card. What could I make this thing do? Anything with a prompt would
> overjoy me at this point.
>
> William Korvine[/color]

It's been awhile. I took the DEC PDP-11/23 Hardware Maintenance Course
in their old MASS. training facilities, plus I haven't seen one in
about ten years. I remember the top slot was where the processor
plugged in, followed by the memory and the DLV11-J. If you leave any
empty slots between cards then you needed a QBus Grant card. The last
slot was the BDV11, which was the bootstrap and bus terminator card.
There were two styles of the backplane. One style used the A and B
slots as QBus slots only and the C and D were used for interconnection
where two cards were needed to make one interface. These systems were
designed pretty well and your not likely to damage anything, it just
won't work when you turn it on. There is only one port, port 1 of 4,
on a DLV11-J quad serial port interface that will give you a console
prompt. Did it come with a serial cable adapter?

Good Luck!

"Meat Loaf" <don.dayton@comcast.net> wrote in news:eradnYFlfb_2M-jfRVn-
[email]tA@comcast.com[/email]:
[color=blue]
> William Korvine wrote:
>[color=green]
>> I just acquired a PDP-11/23.
>>
>> I got it for nostolgic reasons. It was the first computer I used (in
>> high school) and I grew very fond of it. When I saw the chance to get
>> one, I grabbed it.
>>
>> But when I used it in the 70/80s, it was always through a terminal.
>> The computer itself was in the computer room and rarely seen, let
>> alone touched.
>>
>> I literally do not know how to turn this thing on!
>>
>> I have some books, but nothing introductive. They all seem to assume
>> that I have read all the other books :-)
>>
>> I'm a quick learner, but I'm going to have to ask a lot of stupid
>> questions for now. If this isn't the place to ask, perhaps someone
>> could point me there.
>>
>> To get things started, here's sampler of stupid questions:
>>
>> 1. It appears to be a 3U rack-mount drawer. No drives or anything
>> (yet). I hear it's a PDP-11/23. How can I tell for sure.
>>
>> 2. I have 6 half-size boards and 3 full-size boards. Is there a
>> reference to find out what they are?
>>
>> 3. All the boards came out in shipping. Where can I look for
>> information on where they should go.
>>
>> 4. The computer seems to slide freely in a black housing. Is that
>> right?
>>
>> 5. I havn't plugged it in yet. Once I do, how do I turn it on. Better
>> yet, what introductory references might answer this question.
>>
>> 6. I have no disk drive, no tape drive, no storage other than
>> (presumably) RAM. I have what I believe to be a four-port serial
>> card. What could I make this thing do? Anything with a prompt would
>> overjoy me at this point.
>>
>> William Korvine[/color]
>
> It's been awhile. I took the DEC PDP-11/23 Hardware Maintenance Course
> in their old MASS. training facilities, plus I haven't seen one in
> about ten years. I remember the top slot was where the processor
> plugged in, followed by the memory and the DLV11-J. If you leave any
> empty slots between cards then you needed a QBus Grant card. The last
> slot was the BDV11, which was the bootstrap and bus terminator card.
> There were two styles of the backplane. One style used the A and B
> slots as QBus slots only and the C and D were used for interconnection
> where two cards were needed to make one interface. These systems were
> designed pretty well and your not likely to damage anything, it just
> won't work when you turn it on. There is only one port, port 1 of 4,
> on a DLV11-J quad serial port interface that will give you a console
> prompt. Did it come with a serial cable adapter?
>
> Good Luck!
>[/color]

Hi Meat Loaf.

Not sure where you're seeing this, but this thread and a few more describe
my attempts to get the PDP going. Briefly, after pestering the group with
many questings, testing the power supply carefully, checking and setting
jumpers, and extensive reading, I got it running (3 RS232 cables came with
it). By "running" I mean it booted to an ODT prompt.

The only problem is that my drive controller card was physically damaged
and needs about half it's capacitors replaced. Since I have no drives, I
can wait until I bother to do that.

Getting to ODT is really as far as I expected to get at this point. I am
soon going to get replacement caps for the drive controller, but have no
room to mount RL02s so am looking for an alternative.

I notice on E-bay an M7555 MFM controller card. It seems a different
(later) vintage than the 11/23, but I was considering it. Do you know if
it would work? I should be able to dig up an MFM drive somewhere I think.

Thanks for responding.

..wk.

William Korvine wrote:[color=blue]
> I notice on E-bay an M7555 MFM controller card. It seems a different
> (later) vintage than the 11/23, but I was considering it. Do you know if
> it would work? I should be able to dig up an MFM drive somewhere I think.[/color]

Assuming the card is still good, it does work in Qbus systems.
The nomenclature is RQDX3, and it was designed to support the
RX50 dual-5.25" floppy drive and a couple of MFM hard drives
in DEC's RD5x series (or just 4 hard drives without the RX50).
It speaks MSCP via the Qbus, which is supported in later
versions of various OSes but not in older versions. There are
several versions of the RQDX3 ROMs, and to support the largest
drive (RD54) you need ROMs 339E5/340E5. In principle, since
this controller stores the drive geometry parameters on the
disk itself, non-DEC MFM drives could be used (up to 16
surfaces, 2048 cylinders). In practice, some system software
might only support the DEC drive sizes. You would need
formatting software unless you are lucky enough to acquire a
drive already formatted for the RQDX3.

This controller is normally seen only in later boxes (BA23 and
BA123) that contain internal cabling and mounting space for the
RD5x and RX50 drives. However, with sufficient study and work
you should be able to use it with some RD5x drive, sometimes
seen on eBay, or the equivalent under the actual manufacturer's
label (DEC "rebadged" them, in some cases with slight changes).
Here are the equivalents:
DEC RD51 = Seagate ST-412
DEC RD52 = Quantum Q540 (or Evotek ET5540)
DEC RD53 = Micropolis 1325
DEC RD54 = Maxtor XT-2190

Since you don't have the BA23 distribution panel, you need to
convert the RQDX3 J1 connection to the two MFM drive connectors
in some other way. The M9058 module is what is used for this
purpose in the BA123.

There is also an RQDXE module, M7513, used basically to "fan
out" to two BA23 distribution panels when more disks are used
than fit into one box.