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What have we learned from the PDP-11?

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  What have we learned from the PDP-11? RS Wood <rswood@therandymon.com> - 2017-12-06 19:26 -0500
    Re: What have we learned from the PDP-11? Richard Kettlewell <invalid@invalid.invalid> - 2017-12-07 09:12 +0000
    Re: What have we learned from the PDP-11? Huge <Huge@nowhere.much.invalid> - 2017-12-07 09:42 +0000
      Re: What have we learned from the PDP-11? Roger Blake <rogblake@iname.invalid> - 2017-12-07 16:57 +0000
        Re: What have we learned from the PDP-11? Huge <Huge@nowhere.much.invalid> - 2017-12-07 17:15 +0000
          Re: What have we learned from the PDP-11? Roger Blake <rogblake@iname.invalid> - 2017-12-07 17:46 +0000
            Re: What have we learned from the PDP-11? Bob Eager <news0006@eager.cx> - 2017-12-07 21:18 +0000
              Re: What have we learned from the PDP-11? Roger Blake <rogblake@iname.invalid> - 2017-12-07 21:45 +0000
                Re: What have we learned from the PDP-11? Bob Eager <news0006@eager.cx> - 2017-12-07 22:18 +0000
                  Re: What have we learned from the PDP-11? Roger Blake <rogblake@iname.invalid> - 2017-12-08 04:47 +0000
                    Re: What have we learned from the PDP-11? Bob Eager <news0006@eager.cx> - 2017-12-08 12:10 +0000
    Re: What have we learned from the PDP-11? Paul Sture <nospam@sture.ch> - 2017-12-10 19:40 +0100

#15103 — What have we learned from the PDP-11?

https://dave.cheney.net/2017/12/04/what-have-we-learned-from-the-pdp-11



The paper I have chosen tonight is a retrospective on a computer
design. It is one of a series of papers by Gordon Bell, and various
co-authors, spanning the design, growth, and eventual replacement of
the companies iconic line of PDP-11 mini computers.

    C. G. Bell, R. Cady, H. McFarland, B. Delagi, J. O’Laughlin, R.
Noonan and W. Wulf, “A New Architecture for Mini-Computers – The DEC
PDP- 11,” Proceedings of the Sprint Joint Computer Conference, pp.
657-675, AFIPS Press, 1970.

    C. G. Bell, W. D. Strecker, “Computer What Have We Learned from the
PDP-11,” The 3rd Annual Symposium on Computer Architecture Conference
Proceedings, pp. l-14, 1976.

    W. D. Strecker, “VAX-11/780: A Virtual Address Extension to the DEC
PDP-11 Family,” Proceedings of the National Computer Conference, pp.
967-980, AFIPS Press, 1978.

    C. G. Bell, W. D. Strecker, “Retrospective: what have we learned
from the PDP-11—what we have learned from VAX and Alpha”, Proceedings
of the 25th Annual International Symposium on Computer Architecture,
pp. 6-10, 1998.

This year represents the 60th anniversary of the founding of the
company that produced the PDP-11. It is also 40 years since this paper
was written, so I thought it would be entertaining to review Bell’s
retrospective through the lens of our own 20/20 hindsight.

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#15105

RS Wood <rswood@therandymon.com> writes:
> This year represents the 60th anniversary of the founding of the
> company that produced the PDP-11. It is also 40 years since this paper
> was written, so I thought it would be entertaining to review Bell’s
> retrospective through the lens of our own 20/20 hindsight.

Interesting article. A couple of points:

    this pattern of insufficient address bits continues to this day. Who
    remembers the dos 640k limit? Who remembers fighting with himem.sys?
    Who has struggled with 32 bit programs that need more than 2gb of
    heap?

...it certainly continued a long time, but I’m not sure about “to this
day”; it’s rather unusual to run out of address space on a 64-bit
platform. For that matter 32 bit addressing lasted pretty well; I don’t
think it was the wrong decision at the time it was made.

    However to anyone with experience with processors like the ARM, a
    contemporary RISC microprocessor, the similarities between the two
    instruction sets are striking. Just as programming language design
    is a process of evolution and cultural poaching, so too it seems is
    instruction set design.

It’s even more similar to the 68K...

-- 
https://www.greenend.org.uk/rjk/

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#15106

On 2017-12-07, RS Wood <rswood@therandymon.com> wrote:
> https://dave.cheney.net/2017/12/04/what-have-we-learned-from-the-pdp-11

Very interesting, thank you.

(I have a very soft spot for the PDP11, since I worked with them for
the majority of my career.)

-- 
Today is Sweetmorn, the 49th day of The Aftermath in the YOLD 3183
        Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.

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#15108

On 2017-12-07, Huge <Huge@nowhere.much.invalid> wrote:
> (I have a very soft spot for the PDP11, since I worked with them for
> the majority of my career.)

Same here. There was a time when I could practically spit out MACRO-11
code in my sleep. I still have some of my RSX11-M manuals around.

-- 
-----------------------------------------------------------------------------
  Roger Blake (Posts from Google Groups killfiled due to excess spam.)

  NSA sedition and treason        -- http://www.DeathToNSAthugs.com
  Don't talk to cops!             -- http://www.DontTalkToCops.com
  Badges don't grant extra rights -- http://www.CopBlock.org
-----------------------------------------------------------------------------

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#15109

On 2017-12-07, Roger Blake <rogblake@iname.invalid> wrote:
> On 2017-12-07, Huge <Huge@nowhere.much.invalid> wrote:
>> (I have a very soft spot for the PDP11, since I worked with them for
>> the majority of my career.)
>
> Same here. There was a time when I could practically spit out MACRO-11
> code in my sleep. 

LOL. I even wrote some a couple of years ago. Not that I have anything
to run it on. It was for a colleagues' leaving card.

> I still have some of my RSX11-M manuals around.

I threw mine away in a house move, which I now regret. And gave away
my 11/24+ to a computer museum.


-- 
Today is Sweetmorn, the 49th day of The Aftermath in the YOLD 3183
        Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.

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#15110

On 2017-12-07, Huge <Huge@nowhere.much.invalid> wrote:
> I threw mine away in a house move, which I now regret. And gave away
> my 11/24+ to a computer museum.

I've given thought to looking for an old MicroPDP-11 or even a Pro-350
or 380. Keeping one running could be a challenge though and I already have
too much old electronics around the house and not enough time to deal
with it all.

-- 
-----------------------------------------------------------------------------
  Roger Blake (Posts from Google Groups killfiled due to excess spam.)

  NSA sedition and treason        -- http://www.DeathToNSAthugs.com
  Don't talk to cops!             -- http://www.DontTalkToCops.com
  Badges don't grant extra rights -- http://www.CopBlock.org
-----------------------------------------------------------------------------

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#15116

On Thu, 07 Dec 2017 17:46:11 +0000, Roger Blake wrote:

> On 2017-12-07, Huge <Huge@nowhere.much.invalid> wrote:
>> I threw mine away in a house move, which I now regret. And gave away my
>> 11/24+ to a computer museum.
> 
> I've given thought to looking for an old MicroPDP-11 or even a Pro-350
> or 380. Keeping one running could be a challenge though and I already
> have too much old electronics around the house and not enough time to
> deal with it all.

I have four! 11/05, 11/23, 11/84 and a MicroPDP-11.

And three VAXes.

I too could almost spit out Macro-11 or Macro-32 in my sleep.

-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#15117

On 2017-12-07, Bob Eager <news0006@eager.cx> wrote:
> I have four! 11/05, 11/23, 11/84 and a MicroPDP-11.
> And three VAXes.
> I too could almost spit out Macro-11 or Macro-32 in my sleep.

My hat's off to you, sir! The ultimate would be to have a DECSYSTEM-20
of course. (Remember, if you don't have 36 bits you're not playing
with a full DEC.) I would not want to pay for the 3-phase power hookup
required or the resulting electric bills though!

-- 
-----------------------------------------------------------------------------
  Roger Blake (Posts from Google Groups killfiled due to excess spam.)

  NSA sedition and treason        -- http://www.DeathToNSAthugs.com
  Don't talk to cops!             -- http://www.DontTalkToCops.com
  Badges don't grant extra rights -- http://www.CopBlock.org
-----------------------------------------------------------------------------

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#15118

On Thu, 07 Dec 2017 21:45:03 +0000, Roger Blake wrote:

> On 2017-12-07, Bob Eager <news0006@eager.cx> wrote:
>> I have four! 11/05, 11/23, 11/84 and a MicroPDP-11.
>> And three VAXes.
>> I too could almost spit out Macro-11 or Macro-32 in my sleep.
> 
> My hat's off to you, sir! The ultimate would be to have a DECSYSTEM-20
> of course. (Remember, if you don't have 36 bits you're not playing with
> a full DEC.) I would not want to pay for the 3-phase power hookup
> required or the resulting electric bills though!

I would love one. I could do Macro-10 too.

Today I was able to look, close up, at a KA-10 console.

-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#15120

On 2017-12-07, Bob Eager <news0006@eager.cx> wrote:
> I would love one. I could do Macro-10 too.

Never got into assembler on those, but was involved in an APL project.
(Gotta love a language that looks like bursts of line noise!)

-- 
-----------------------------------------------------------------------------
  Roger Blake (Posts from Google Groups killfiled due to excess spam.)

  NSA sedition and treason        -- http://www.DeathToNSAthugs.com
  Don't talk to cops!             -- http://www.DontTalkToCops.com
  Badges don't grant extra rights -- http://www.CopBlock.org
-----------------------------------------------------------------------------

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#15121

On Fri, 08 Dec 2017 04:47:05 +0000, Roger Blake wrote:

> On 2017-12-07, Bob Eager <news0006@eager.cx> wrote:
>> I would love one. I could do Macro-10 too.
> 
> Never got into assembler on those, but was involved in an APL project.
> (Gotta love a language that looks like bursts of line noise!)

Completely orthogonal set of conditional instructions.

JUMP is a no-op; you have to use JUMPA (Always)

Althought it's faster to use JRST 0,  (jump and restore no flags)!

-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#15123

On 2017-12-07, RS Wood <rswood@therandymon.com> wrote:
> https://dave.cheney.net/2017/12/04/what-have-we-learned-from-the-pdp-11
>
> The paper I have chosen tonight is a retrospective on a computer
> design. It is one of a series of papers by Gordon Bell, and various
> co-authors, spanning the design, growth, and eventual replacement of
> the companies iconic line of PDP-11 mini computers.

Thanks for that.  Gordon Bell's papers have always been a good read.

What I learned from the PDP-11 was that you didn't need a room full of
mainframe with associated aircon, when you could repurpose a much
smaller and less expensive machine that had previously been been the
preserver of scientific or manufacturing processes into something which
could be used for commercial purposes, namely order processing and
accounts.

This brought serious computing capability within the budgets of many
smaller companies.

From the article:

"What Oslen and Anderson recognised was the desire for an interactive
computer experience was so strong that there was a market for “small”
computers dedicated to this role."

What that philosophy gave us by the mid to late 70s was a variety of
systems where IT departments could provide interactive programs which
worked on VDUs sitting in the users' departments.  This allowed IT
departments to jetison the traditional data gathering and input
processes required of punch card systems, give the end-user departments
responsibility for their own data, and instead concentrate on developing
implementing better processes to support the business.

-- 
Everybody has a testing environment. Some people are lucky enough to
have a totally separate environment to run production in.

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