[pups] PDP-9?

[pups] PDP-9?

[Fred N. van Kempen]

Unix was _developed_ on the 11/20.  The first versions (up to  the
fourth or fifth edition or so) didn't require an MMU, and, therfore,
had no protection whatsoever.

Dennis... tell us the "All out?" story.. please.. :)

--fred

> -----Original Message-----
> From: Dave Horsfall [mailto:dave at horsfall.org]
> Sent: Monday, September 02, 2002 3:02 AM
> To: PDP Unix Preservation Society
> Subject: Re: [pups] PDP-9?
> 
> 
> On Sun, 18 Aug 2002, Lars Buitinck wrote:
> 
> > we all know that UNIX first ran on the PDP-7 and then on 
> the PDP-11/20,
> 
> Just got back from overseas, but this doesn't seem to have 
> been addressed:
> AFAIK, Unix never ran on the 11/20 (no MM unit); did you mean 
> a DEC-20?
> 
> -- 
> Dave Horsfall  DTM  VK2KFU  dave at esi.com.au  Ph: +61 2 
> 9906-3377 Fx: 9906-3468
> (Unix Guru) Pacific ESI, Unit 22, 8 Campbell St, Artarmon, 
> NSW 2065, Australia
> 
> _______________________________________________
> PUPS mailing list
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> http://minnie.tuhs.org/mailman/listinfo/pups
> 

[pups] PDP-9?

[Warren Toomey]

In article by Fred N. van Kempen:
> Unix was _developed_ on the 11/20.  The first versions (up to  the
> fourth or fifth edition or so) didn't require an MMU, and, therfore,
> had no protection whatsoever.
> 
> Dennis... tell us the "All out?" story.. please.. :)
> --fred

Was it this story (from http://cm.bell-labs.com/cm/cs/who/dmr/odd.html):

Back around 1970-71, Unix on the PDP-11/20 ran on hardware that
not only did not support virtual memory, but didn't support any
kind of hardware memory mapping or protection, for example against
writing over the kernel. This was a pain, because we were using
the machine for multiple users. When anyone was working on a program,
it was considered a courtesy to yell "A.OUT?" before trying it, to
warn others to save whatever they were editing.

[A substory: at some point several were sitting around working
away. Bob Morris asked, almost conversationally, "what are the
arguments to ld?" Someone told him. We continued typing for the
next minute, as a thought began to percolate, not quite to the top
of the brain - in other words, not quite fast enough. The terminal
stopped echoing before anyone could stop and say "Hold on Bob, what
is it you're trying to do?"]

Warren

[pups] PDP-9?

[Norman Wilson]

Dave Horsfall:

  AFAIK, Unix never ran on the 11/20 (no MM unit); did you mean a DEC-20?

I don't know if it was called an 11/20 at the time (I seem to recall
some model-number upheaval in the early days of the -11), but the first
PDP-11 UNIX system was certainly one without memory management:

  By the beginning of 1970, PDP-7 UNIX was a going concern ... In early
  1970 we proposed acquisition of a PDP-11, which had just been introduced
  by Digital ... to create a system specifically designed for editing and
  formatting text, what might today be called a `word-processing system.'
  ... During the last half of 1971, we supported three typists from the
  Patent Department, who spent the day busily typing, editing, and formatting
  patent applications, and meanwhile tried to carry on our own work.  UNIX
  has a reputation for supplying interesting services on modest hardware,
  and this period may mark a high point in the benefit/equipment ratio;
  on a machine with no memory protection and a single 0.5-MB disk, every
  test of a new program required care and boldness, because it could easily
  crash the system, and every few hours' work by the typists meant pushing
  out more information onto DECtape, because of the very small disk.

  The experiment was trying but successful.  Not only did the Patent
  Department adopt UNIX, and thus become the first of many groups at the
  Laboratories to ratify our work, but we achieved sufficient credibility
  to convince our own management to acquire one of the first PDP-11/45
  systems made.

Dennis M. Ritchie, Evolution of the UNIX Time-Sharing System; AT&T Bell
Labs Technical Journal, Vol. 63 No. 8 Part 2, October 1984.

Maybe Dennis will chime in with further memories.

Certainly there's nothing odd about UNIX running without memory protection,
though, especially in that era.  The PDP-7 had none.  The trick was that
every context switch was also a swap.  The scheme was revived in the late
1970s for the early, no-memory-map versions of the LSI-11 (called LSX and
later Mini-UNIX; paper by Lycklama et al in the 1978 all-UNIX BLTJ, I believe).

I suppose next some whippersnapper will express disbelief that UNIX
could have run on a system with no Ethernet interface.  You mean there
was life before 10BaseT, spam, and pornographic web sites?

(Not, to be fair, that Dave Horsfall is a whippersnapper.)

Norman Wilson
Toronto ON
(Still on the shelf, but crawling toward the edge)

[pups] PDP-9?

[Greg Lehey]

On Sunday,  1 September 2002 at 21:54:57 -0400, Norman Wilson wrote:
> Dave Horsfall:
>
>   AFAIK, Unix never ran on the 11/20 (no MM unit); did you mean a DEC-20?
>
> I don't know if it was called an 11/20 at the time (I seem to recall
> some model-number upheaval in the early days of the -11),

The 11/20 was definitely called like that in early 1970.  IIRC it was
also the first PDP-11 model; it was certainly the first I heard of.
The quote below tends to reinforce this viewpoint.

> but the first PDP-11 UNIX system was certainly one without memory
> management:
>
>   By the beginning of 1970, PDP-7 UNIX was a going concern ... In early
>   1970 we proposed acquisition of a PDP-11, which had just been introduced
>   by Digital

Greg
--
Finger grog at lemis.com for PGP public key
See complete headers for address and phone numbers

[pups] PDP-9?

[Johnny Billquist]

On Mon, 2 Sep 2002, Dave Horsfall wrote:

> On Sun, 18 Aug 2002, Lars Buitinck wrote:
> 
> > we all know that UNIX first ran on the PDP-7 and then on the PDP-11/20,
> 
> Just got back from overseas, but this doesn't seem to have been addressed:
> AFAIK, Unix never ran on the 11/20 (no MM unit); did you mean a DEC-20?

Um? Who said Unix used an MMU in the beginning?

No, Unix never ran on a PDP-10. It was PDP-7 and then the PDP-11, and I
believe it was a PDP-11/20 at the beginning.

	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt at update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

[pups] PDP-9?

[Lars Buitinck]

we all know that UNIX first ran on the PDP-7 and then on the PDP-11/20,
but does anyone know anything about PDP-9 UNIX?  it\'s mentioned in \"The
UNIX Time-Sharing System\" in the V7 manual:

\"The earliest [version of UNIX] (circa 1969-70) ran on the Digital
Equipment Corporation PDP-7 and -9 computers.\"

--
If I travelled to the end of the rainbow
As Dame Fortune did intend
Murphy would be there to tell me
The pot is at the other end

Lars

[pups] PDP-9?

[Johnny Billquist]

On Sun, 18 Aug 2002, Lars Buitinck wrote:

> we all know that UNIX first ran on the PDP-7 and then on the PDP-11/20,
> but does anyone know anything about PDP-9 UNIX?  it\'s mentioned in \"The
> UNIX Time-Sharing System\" in the V7 manual:
> 
> \"The earliest [version of UNIX] (circa 1969-70) ran on the Digital
> Equipment Corporation PDP-7 and -9 computers.\"

Hmmm, I cannot exactly answer that, but the PDP-7 and PDP-9 were both
18-bit machines, and somewhat compatible, I believe.
The whole line is (I believe):

PDP-4 -> PDP-7 -> PDP-9 -> PDP-15

So I guess that if you had it running on a PDP-7, you could probably
almost take the code unmodified and run it on the PDP-9.
The PDP-15 have a different bus (Unibus?) I believe, and thus,
peripherials are different from the predecessors.
This obviosuly affects the OS. :-)

	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt at update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol