Learning PDP-11 in 2021

[Jason Evans]

I've never used one of the big old great computers like a PDP-11.

Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?

What emulator would you use and what guide would you use to get going?

__
JE

[Bob Eager]

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.
Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?
What emulator would you use and what guide would you use to get going?

SIMH, I would say. Wtitten by a DEC guy who really knows his stuff. You
can select the model to emulate, etc.

A choice of operating systems (and I'll be adding another soon). Plenty
of documentation for it all online, mainly at bitsavers.

There may be flashy ones with GUI panels, but I've been using SIMH for
years and it is *very* solid.

[Schmitty]

Post by Bob Eager

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.
Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?
What emulator would you use and what guide would you use to get going?

SIMH, I would say. Wtitten by a DEC guy who really knows his stuff. You
can select the model to emulate, etc.
A choice of operating systems (and I'll be adding another soon). Plenty
of documentation for it all online, mainly at bitsavers.
There may be flashy ones with GUI panels, but I've been using SIMH for
years and it is *very* solid.

You could even run ancient Unix on it, see
http://wandel.ca/homepage/unixdemo.html

[Bob Eager]

Post by Schmitty

Post by Bob Eager

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.
Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?
What emulator would you use and what guide would you use to get going?

SIMH, I would say. Wtitten by a DEC guy who really knows his stuff. You
can select the model to emulate, etc.
A choice of operating systems (and I'll be adding another soon). Plenty
of documentation for it all online, mainly at bitsavers.
There may be flashy ones with GUI panels, but I've been using SIMH for
years and it is *very* solid.

You could even run ancient Unix on it, see
http://wandel.ca/homepage/unixdemo.html

Oh, I know, Lots of versions up to Seventh Edition. Takes me back to when
I first used Sixth Edition in 1975.

http://simh.trailing-edge.com/software.html

I did the (rare) Mini-UNIX stuff, and the Quasijarus stuff for the VAX.
Just the pages and instructions, not the software!

[David Bridgham]

Besides SimH for the emulator, if you want a bit of the look and feel of
the old 11's there's also the PiDP-11.

https://obsolescence.wixsite.com/obsolescence/pidp-11

You then need to add a big fan to get the whooshing sound. Maybe you
should just skip that part.

Dave

[g***@gmail.com]

Post by David Bridgham
You then need to add a big fan to get the whooshing sound. Maybe you
should just skip that part.

You can probably get that as a sample. Play it through a Bluetooth speaker.

------------------------------------------------------------------------

if love is a drug, then, ideally, it's a healing, healthful drug... it's
kind of like prozac is supposed to work (without the sexual side
effects and long-term damage to the brain and psyche)

[Questor]

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.

One of the reasons why the PDP-11 was a great computer was because it wasn't
big. You didn't need a raised-floor computer room with a heavy-duty HVAC
system. Ordinary office air-conditioning was usually sufficient. Was 3-phase
power required for the PDP-11 or its peripherals? If not, that would be another
plus for the smaller models.

[Andy Walker]

Post by Questor
One of the reasons why the PDP-11 was a great computer was because it wasn't
big. You didn't need a raised-floor computer room [...].

Indeed. We carved our computer room out of a basement that
previously contained rather extravagant Ladies and Gents facilities.
The puddles on the floor had been put down to the Gents being less
than gentlemanly, so a raised floor was deemed unnecessary. However,
next time it rained, more puddles. We rang the Works Dept, and
said that unless something could be done in the next hour or so,
some very expensive* computers were in danger. A pump was rapidly
deployed and the danger averted. But it turned out that the [award-
winning] building, by a Famous Architect, had been built over an
un-noticed stream, which flooded every time it rained. Red faces in
the FA's offices.

Yes, the PDP-11 was a great computer. For the first time we
were freed from the tyranny of computers the size of rooms or even
buildings and needing dedicated operators and engineers.

_____
* Expensive by the standards of maths depts, not by the
standards of computing centres.

[Anne & Lynn Wheeler]

Post by Andy Walker
Indeed. We carved our computer room out of a basement that
previously contained rather extravagant Ladies and Gents facilities.
The puddles on the floor had been put down to the Gents being less
than gentlemanly, so a raised floor was deemed unnecessary. However,
next time it rained, more puddles. We rang the Works Dept, and
said that unless something could be done in the next hour or so,
some very expensive* computers were in danger. A pump was rapidly
deployed and the danger averted. But it turned out that the [award-
winning] building, by a Famous Architect, had been built over an
un-noticed stream, which flooded every time it rained. Red faces in
the FA's offices.

drift computer room flooding

new STL lab opened in the 70s (ref gone 404, but lives on at wayback machine
https://web.archive.org/web/20080512195924/http://www.ajnordley.com/IBM/Air/SVL/

the above article mentions the interior couryard between the towers and
above "one of the largest computer machine rooms west of the
Mississippi". it also mentions flooding of roads ... but when STL first
open, the computer room was also getting flooded when it rained.

STL also had a different problem opening. IBM had standard naming after
closest Post Office, which was Coyote. However just prior to opening,
the SanFran professional ladies Coyote organization was demonstrating in
Wash DC gov. bldgs. The name was quickly changed to closest cross
street, Santa Teresa (STL) ... more recently changed to Silicon Vally
Lab (SVL).

In the 60s, as undergraduate, I took two semester hr intro to
computers/fortran ... then within a year, I'm hired fulltime responsible
for IBM systems. Then before I graduate, I'm hired fulltime into small
group in the Boeing CFO office to help with the formation of Boeing
Computer Services (consolidate all dataprocessing into independent
business unit to better monetize the investment, including offering
services to non-Boeing entities). I thought Renton datacenter was
possibly largest in the world, 360/65s arriving faster than they could
be installed, boxes constantly staged in the hallways around the machine
room ($200M-$300M in IBM 360s). There was also disaster plan to
replicate renton up at the new 747 plant in Everett (747#3 was flying
skies of Seattle getting FAA flt certification), where Mt. Rainier heats
up and the resulting mud slide takes out the datacenter. The analysis
claimed that being w/o Renton for a week would cost Boeing more than
the cost of replicating the datacenter.

[gareth evans]

Post by Questor

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.

One of the reasons why the PDP-11 was a great computer was because it wasn't
big. You didn't need a raised-floor computer room with a heavy-duty HVAC
system. Ordinary office air-conditioning was usually sufficient. Was 3-phase
power required for the PDP-11 or its peripherals? If not, that would be another
plus for the smaller models.

... and the original 28 foot long unibus getting trodden into the floor
and still functioning!

[Jon Elson]

On Mon, 10 May 2021 07:44:19 -0000 (UTC), Jason Evans

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.

One of the reasons why the PDP-11 was a great computer was because it wasn't
big. You didn't need a raised-floor computer room with a heavy-duty HVAC
system. Ordinary office air-conditioning was usually sufficient. Was 3-phase
power required for the PDP-11 or its peripherals? If not, that would be
another plus for the smaller models.

I don't know of any PDP-11 that required 3-phase. Smaller models ran off
120 V AC from a standard wall outlet, maybe our 11/45 used 208 V single
phase. I do remember some issue when it arrived and I tapped it into the
breaker panel until somebody from facilities saw that we had to have a
proper high-power outlet put in.

Some of the bigger disks using Massbus might have needed 3-phase.
I know RP07 did, but that was on our VAX 11/780.

Jon

[Lawrence Statton (NK1G)]

Post by Jon Elson

Was 3-phase power required for the PDP-11 or its peripherals? If
not, that would be another plus for the smaller models.

I don't know of any PDP-11 that required 3-phase. Smaller models ran off
120 V AC from a standard wall outlet, maybe our 11/45 used 208 V single
phase. I do remember some issue when it arrived and I tapped it into the
breaker panel until somebody from facilities saw that we had to have a
proper high-power outlet put in.
Some of the bigger disks using Massbus might have needed 3-phase.
I know RP07 did, but that was on our VAX 11/780.
Jon

This used to be a fairly frequently covered topic 20+ years ago here.
IIRC, some of the largest (11/70-class) machines came with 3-ph power
controllers, but each of the individual loads were strappable for 120V
(for North American customers)

I know my 11/55 with "a couple of RL02 and a couple of RK07" was all
120, but the inlet was 120/240 single phase.


echo "***@abaluon.abaom" | sed s/aba/c/g

[Marco Scholz]

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.
Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?

[...]

Simh simulates PDP-1, -4, -7, -8, -9, -10 and -11.

However, a PiDP-11 will be the most fun, IMO:

"The PiDP-11 is a modern replica of the PDP-11/70."`
https://obsolescence.wixsite.com/obsolescence/pidp-11

Especially if you like toggles, switches and blinkenlihghts.

[Bob Eager]

Post by Marco Scholz

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.
Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?

[...]
Simh simulates PDP-1, -4, -7, -8, -9, -10 and -11.
"The PiDP-11 is a modern replica of the PDP-11/70."`
https://obsolescence.wixsite.com/obsolescence/pidp-11
Especially if you like toggles, switches and blinkenlihghts.

Agreed, but it's SIMH inside. And SIMH is cheaper (free)!

(I'm still going to get a PiDP-10 to join the -8 and -11).

[Vir Campestris]

Post by Bob Eager
(I'm still going to get a PiDP-10 to join the -8 and -11).

I cut my teeth on a PDP-10, the first thing I ever used assembler on.

There's something to do in my retirement!

Andy

[Bob Eager]

Post by Vir Campestris

Post by Bob Eager
(I'm still going to get a PiDP-10 to join the -8 and -11).

I cut my teeth on a PDP-10, the first thing I ever used assembler on.
There's something to do in my retirement!

It was the third fort me - my Master's at Essex.

[Andreas Kohlbach]

Post by Marco Scholz

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.
Let's say I'm nuts or at least a big nerd. If I wanted to learn how to
use one today without spending exorbitant amounts of money buying
hardware and a ton of old manuals, how could I go about doing that?

[...]
Simh simulates PDP-1, -4, -7, -8, -9, -10 and -11.

Apparently I can emulate a PDP-1 (from 1961?) in MAME, although MAME is
supposed to only emulate machines with a microprocessor as CPU. So
machines with i4004 (1971) upwards. Strange.

[g***@gmail.com]

This post might be inappropriate. Click to display it.

[Ahem A Rivet's Shot]

On Thu, 24 Jun 2021 19:40:13 GMT

Post by g***@gmail.com
I suppose B&W CRTs were cheaper,
but the amount of profit arcade games made, surely they could have
afforded colour? And make the effort to squeeze a couple more chips in so
we actually got maybe 5 or 6 colours all on the screen at once! Actually
yeah I can see why they didn't bother, often there were very few objects
on screen at all, or very few types of object, with multiples of them.

There's another reason - colour would have made the bit shuffling
*much* more complex - the ones with CPUs were running flat out as it was so
the games would have slowed down, as for the dedicated chips - they were
maxed out too colour would have been too much logic.

Post by g***@gmail.com
Still I reckon colour would have stood out in the arcade. But maybe any
screen at all did, and that was enough.

The original space invaders had a B&W screen with a gel filter at
the bottom to make the invaders change colour when they got close.
Strangely the screens were at the bottom facing up, what the player looked
at was a mirror at 45 degrees.

[Scott Lurndal]

Post by Ahem A Rivet's Shot
On Thu, 24 Jun 2021 19:40:13 GMT

Post by g***@gmail.com
I suppose B&W CRTs were cheaper,
but the amount of profit arcade games made, surely they could have
afforded colour? And make the effort to squeeze a couple more chips in so
we actually got maybe 5 or 6 colours all on the screen at once! Actually
yeah I can see why they didn't bother, often there were very few objects
on screen at all, or very few types of object, with multiples of them.

There's another reason - colour would have made the bit shuffling
*much* more complex - the ones with CPUs were running flat out as it was so
the games would have slowed down, as for the dedicated chips - they were
maxed out too colour would have been too much logic.

Post by g***@gmail.com
Still I reckon colour would have stood out in the arcade. But maybe any
screen at all did, and that was enough.

The original space invaders had a B&W screen with a gel filter at
the bottom to make the invaders change colour when they got close.
Strangely the screens were at the bottom facing up, what the player looked
at was a mirror at 45 degrees.

Which allowed a smaller cabinet footprint, IIRC.

[Ahem A Rivet's Shot]

On Fri, 25 Jun 2021 14:21:59 GMT

Post by Scott Lurndal

Post by Ahem A Rivet's Shot
The original space invaders had a B&W screen with a gel filter at
the bottom to make the invaders change colour when they got close.
Strangely the screens were at the bottom facing up, what the player
looked at was a mirror at 45 degrees.

Which allowed a smaller cabinet footprint, IIRC.

I can see how it would - very clever whoever came up with that! I
imagine the target footprint was that of the typical one armed bandit.

[Andreas Kohlbach]

This post might be inappropriate. Click to display it.

[John Goerzen]

Post by Jason Evans
I've never used one of the big old great computers like a PDP-11.

You might appreciate my project at
https://github.com/jgoerzen/vintage-computing . It features support for
both Raspberyy Pi and Docker, offering various emulators and ancient OS
distributions to run under them. The Github readme also contains a lot
of links to emulators and sources of OSs to get you going.

- John

[j***@SDF.ORG]

Post by John Goerzen
You might appreciate my project at
https://github.com/jgoerzen/vintage-computing . It features support for
both Raspberyy Pi and Docker, offering various emulators and ancient OS
distributions to run under them. The Github readme also contains a lot
of links to emulators and sources of OSs to get you going.

Thanks John, I'll check it out. It's also great to see another SDF member!

Best Regards,
jse