[TUHS] PDP-11 questions

[TUHS] PDP-11 questions

[Mark Longridge]

Ok, I got a few questions about PDP-11.

First, I was wondering when Bell Labs got that first PDP-11/20 what
software (if any) came with it? I assume when one bought a PDP-11/20
you would get some type of OS with it.

According to the folks at alt.sys.pdp11 the PDP-11 computer doesn't
have anything equivalent to a PC's BIOS. But I know a bit about what a
PC's BIOS does and that includes RAM Initialization. Wouldn't the DRAM
on the PDP-11/something need to be initialized too? Perhaps an older
PDP-11 doesn't have DRAM but surely the later models did?

Now the last question has to do with what made the PDP-11 architecture
so great. Part of that had to be the relatively affordablility of the
PDP-11 and of course it was the machine that made Unix possible. It
seems though that there should have been a PDP-11 based desktop and as
far as I can tell that didn't happen. Instead we got a bunch of micros
with 8080, z80 and 6502 cpus, but nothing that could run Unix, at
least not a Unix v7 with source code.

Mark

[TUHS] [Bulk] PDP-11 questions

[Mark Green]

Whether a PDP11 came with an operating system depended upon how it was purchased, none of the ones that I bought came with an OS.  The PDP11/20 was early in the line, so it may have come with some form of OS.

DRAM on a PDP11/20??  You've got your decades mixed up.  DRAM came much later than the PDP11 architecture.  The PDP11/20 used core memory, no need for initialization.  Core is non-volatile, so it maintained its contents when power was removed.  It was common to keep whatever software you were using in memory, so when you came back you just turned on the power and continued from where you were.  One of the groups that I worked with used to keep all their software libraries on core boards, they would switch the boards between computers between computers whenever they needed to library.

All the early PDP11s had full consoles, so a boot loader could be entered through the console.  There were ROM boards that had some of the common bootstraps.

There were desktop PDP11s, depending upon what you mean by a desktop.  Healthkit produced a low end PDP11 system for hobbyists that would be considered to be a desktop.  DEC was slow getting into that area, there were some desktop like PDP11 systems produced near the end of the architecture, but DEC desktops really didn't appear until the VAX and MIPS era.

-----Original Message-----
From: TUHS [mailto:tuhs-bounces@minnie.tuhs.org] On Behalf Of Mark Longridge
Sent: January 24, 2016 12:37 PM
To: tuhs <tuhs at minnie.tuhs.org>
Subject: [Bulk] [TUHS] PDP-11 questions

Ok, I got a few questions about PDP-11.

First, I was wondering when Bell Labs got that first PDP-11/20 what software (if any) came with it? I assume when one bought a PDP-11/20 you would get some type of OS with it.

According to the folks at alt.sys.pdp11 the PDP-11 computer doesn't have anything equivalent to a PC's BIOS. But I know a bit about what a PC's BIOS does and that includes RAM Initialization. Wouldn't the DRAM on the PDP-11/something need to be initialized too? Perhaps an older
PDP-11 doesn't have DRAM but surely the later models did?

Now the last question has to do with what made the PDP-11 architecture so great. Part of that had to be the relatively affordablility of the
PDP-11 and of course it was the machine that made Unix possible. It seems though that there should have been a PDP-11 based desktop and as far as I can tell that didn't happen. Instead we got a bunch of micros with 8080, z80 and 6502 cpus, but nothing that could run Unix, at least not a Unix v7 with source code.

Mark


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[TUHS] PDP-11 questions

[Clem Cole]

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​below​

On Sun, Jan 24, 2016 at 12:37 PM, Mark Longridge <cubexyz at gmail.com> wrote:

> Ok, I got a few questions about PDP-11.
>
> First, I was wondering when Bell Labs got that first PDP-11/20 what
> software (if any) came with it? I assume when one bought a PDP-11/20
> you would get some type of OS with it.
>
​SW?? We don't need no stinking SW - we do our own..

Seriously, SW was an option you paid for. The system came with paper tapes
to run diagnostics to prove the system worked.   And when they got their
first 11, there is no disk and DOS-11( it's 1st OS) was not yet released
IIRC.  ​

Have to ask Ken, but my guess and I think one or more of the BLTJ articles
back it up, the would have purchased it as it.   Maybe an standalone
assembler running from paper tape or DEC tape.  But whatever it had, it
would have been very, very limited.

But that was not an issue, they had other systems and could write their own
tools and cross assemble or compile them as needed (which is what they
did).




> According to the folks at alt.sys.pdp11 the PDP-11 computer doesn't
> have anything equivalent to a PC's BIOS.
>
​Sigh... Kids these days .... more in a minute....​




> ​... ​
> Wouldn't the DRAM
> ​ ​
> on the PDP-11/something need to be initialized too?
>
​What's DRAM -- early 11's had core.   That said, Intel was selling the
1101 (1k x1 bit) chips which were being consumed at a pretty good rate for
the memory systems for PDP-10s​.    DEC would not release a DRAM board for
the 11 for a few more years.   It was 2K x 16 bits (with ECC IIRC).    And
they were pretty pricy.   I seem to remember the had faster access times
that the core boards, but I'm hazy on that.

When UNIX starts to leak to the Universities in the mid to late 70's many
(??most??) of us are using DRAM on our 11's but we would often by the
minimum config from DEC and the use after market DRAM boards.   We have a
very early serial # 11/34 under 10 IIRC in the EE Dept at CMU (One of my
claims to fame was bring UNIX up on it for the first time - by hacking the
11/40 support - although I think Noel and few others did it in other places
too there after).

Anyway - that system had 24K words (48K bytes) of DRAM memory on it to
start with.  We made some memory board for it ourselves to max it to 128K
words and National Semi memory chips.   I remember the value of the memory
chips was greater than the CPU at that point.

​Anyway - core machine you did not want to init.  You usually left the OS
or whatever in place.
It's going to be interesting to see if this becomes the new norm with the
Crystal Ridge (Xpoint 3D or whatever marketing is calling it).


Perhaps an older
> PDP-11 doesn't have DRAM but surely the later models did?
>
Sure by why the pre-boot have to do it?  Init of the memory system is done
by the OS.   Look at the code in V6 and V7 that is called very early and
prints out the size of the memory it finds.   It's working backwards until
it find memory that responds and clears it out.

There are a few parts/functions to the BIOS rooms and fear you may be
mashing the together.
Init of the memory system is not done in the original PC BIOS the way it is
done now.  There reason is because today we have memory controller chips
with lots and lots of different options.
The firmware BIOS is used to set up that controller (pre-boot).   The 11
(and the Vax for that matter) did not have such an idea.   What we call the
memory controller was just part of the logic in the CPU.
​


> ​... ​
> It
> ​ ​
> seems though that there should have been a PDP-11 based desktop and as
> far as I can tell that didn't happen. Instead we got a bunch of micros
> with 8080, z80 and 6502 cpus, but nothing that could run Unix, at
> least not a Unix v7 with source code.
>
​I can see from an later observers view you might fall into a trap thinking
this, but a bunch of it is actually not true.

1)  There were small form factor PDP-11's that did appear late in the
PDP-11's life.   Some based on the LSI-11 and some even on the F-11/J-11
(single chip 11).   DEC had a line called DEC Processional series.  But
they really were not super popular.  But as other point out, DEC was slow
to recognize this as a market. In fact a professor at Harvard business
explain the problem at DEC and coins a term for the behavior when the 8 bit
and 16 bit micros appear [Clay Christiansen's book "The Innovators'
Dilemma" - the term is call "disruptive technology."]

FWIW:  At this time, Wang Labs (Dr. Wang invented the core memory at IBM
BTW, was selling a system for secretaries / admin that ran originally on an
8080, later a Z80.   It was quite popular for what it could do... which was
allow them to edit letters/documents.   But it was very much focused on a
specific market/task - which interestingly enough was the original task
UNIX had ;-)

Also by the time DEC did try to build a workstation (after Masscomp,
Apollo, Sun et al had taken many of their engineers) it was too little too
late.   The ship had sailed and they never recovered that market.

2) Economics was really the reason.  Please understand in the 1975 dollars,
a 11/34 with 2 RK05's, 24K words of memory and a single serial interface
cost about $45K.​    If you want to a 9-track tape drive that was another
4-8K, 200M RPxx style disk, another $15K, as I said the chips to make the
memory was $45K.  Much less, serial ports, a printer etc....

Using an 11 for "personal" computer was not cost effective.   You would
need to get the prices of memory, large storage, down and size/speed of the
processors in single chip form before you really do it.

That said with birth of the IBM PC, Andy Tannebaum wrote a really good Unix
V7 clone for the 16 bit 8088 - called Minux.   And V& itself began to move
to more capable micro's    But DEC was making a huge amount of money
selling Vaxen.   So the workstations and small capability systems were not
interesting (see Christiansen for why).

3)  Some people actually did get UNIX or close to unix functionality
running on the 8-bit machines.  The Guy who wrote BDS C (Brain Damaged
Software) brought an 8" floppy disk based Z80 system that originally had
been running CP/M to a Usenix in the late 1970's/early 1980s and showed a
couple of us including Dennis his OS.   I remember Dennis being pretty
impressed and stating that was it was fast and as good as he remember early
UNIX.   He was quite encouraging.
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[TUHS] PDP-11 questions

[Dave Horsfall]

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On Sun, 24 Jan 2016, Clem Cole wrote:

> We have a very early serial # 11/34 under 10 IIRC in the EE Dept at CMU 
> (One of my claims to fame was bring UNIX up on it for the first time - 
> by hacking the 11/40 support - although I think Noel and few others did 
> it in other places too there after).  

[ Warning: self-promotion ahead ]

I believe that I was the first to port Unix (V6) to the 11/34 in 
Australia; there should be a paper that I wrote, somewhere in the 
archives.  I was not aware of any prior work at the time, although 
subsequently a couple of bods came out to say that they'd beaten me to it 
(then why didn't they publish?).

In the words of the inimitable Tom Lehrer: "I publish first!".

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."

[TUHS] PDP-11 questions

[Warren Toomey]

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Implementing Unix on a PDP-11/34, Dave Horsfall, AUUGN 1(6) pg 17, September 1979, see http://www.tuhs.org/Archive/Documentation/AUUGN/AUUGN-V01.6.pdf
Cheers, Warren

On 25 January 2016 1:16:22 pm AEST, Dave Horsfall <dave at horsfall.org> wrote:
>On Sun, 24 Jan 2016, Clem Cole wrote:
>
>> We have a very early serial # 11/34 under 10 IIRC in the EE Dept at
>CMU 
>> (One of my claims to fame was bring UNIX up on it for the first time
>- 
>> by hacking the 11/40 support - although I think Noel and few others
>did 
>> it in other places too there after).  
>
>[ Warning: self-promotion ahead ]
>
>I believe that I was the first to port Unix (V6) to the 11/34 in 
>Australia; there should be a paper that I wrote, somewhere in the 
>archives.  I was not aware of any prior work at the time, although 
>subsequently a couple of bods came out to say that they'd beaten me to
>it 
>(then why didn't they publish?).
>
>In the words of the inimitable Tom Lehrer: "I publish first!".
>
>-- 
>Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will
>suffer."

-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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[TUHS] PDP-11 questions

[Clem cole]

Dave not doubt. Sorry. I didn't  publish.  FWIW Ted took that code back to  the USG though :-).  I've forgotten when the 34 was released. I think it was late 77 maybe early 78 but it was before 79 as the 34/A would have been by then. (I'll have to ask Jeff Mitchell who did the CPU if I see him anytime soon). 


BTW Because Gordon Bell was a CMU prof , we tended to have early DEC product. Urban legend is Bell  would match transistors to make the amplifiers by hand when he designed the for runner to 8 cpu. 

We had serial #1 of the Vax and our EE dept had serial #9 of the 8 and I fairly sure the 34 was under 10 too.  My memory is that was the summer of '77.  Danny Klein and I wrote the original RK07 driver for UNIX a year later because we had a very early one of those.

  Another infamous story of CMU and early processors was the KL10 in late 75/early 76.  DEC's site prep book for the KL series had not been written and CMU wired for a KA10 not know any better.  When DEC first powered up, it blew the main circuit in Science Hall putting us all in the bldg in darkness.  I was in the computer room when it went completely silent and dark - very strange. 

Sent from my iPhone

> On Jan 25, 2016, at 12:32 AM, Warren Toomey <wkt at tuhs.org> wrote:
> 
> Implementing Unix on a PDP-11/34, Dave Horsfall, AUUGN 1(6) pg 17, September 1979, see http://www.tuhs.org/Archive/Documentation/AUUGN/AUUGN-V01.6.pdf
> Cheers, Warren
> 
>> On 25 January 2016 1:16:22 pm AEST, Dave Horsfall <dave at horsfall.org> wrote:
>>> On Sun, 24 Jan 2016, Clem Cole wrote:
>>> 
>>>  We have a very early serial # 11/34 under 10 IIRC in the EE Dept at CMU 
>>>  (One of my claims to fame was bring UNIX up on it for the first time - 
>>>  by hacking the 11/40 support - although I think Noel and few others did 
>>>  it in other places too there after).  
>> 
>> [ Warning: self-promotion ahead ]
>> 
>> I believe that I was the first to port Unix (V6) to the 11/34 in 
>> Australia; there should be a paper that I wrote, somewhere in the 
>> archives.  I was not aware of any prior work at the time, although 
>> subsequently a couple of bods came out to say that they'd beaten me to it 
>> (then why didn't they publish?).
>> 
>> In the words of the inimitable Tom Lehrer: "I publish first!".
> 
> -- 
> Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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[TUHS] PDP-11 questions

[Lawrence Stewart]

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Regarding the 11/34.

We had one at the Stanford Information Systems Lab sometime in 78 or 79, running (I think) V7, and we certainly didn’t do the port ourselves!  We did put it on the Arpanet though, as SU-ISL.  This
was a pretty weird hookup.  The NCP ran on a front-end LSI-11 (or was it an 11/23?) and there was
a Very Distant Host interface home-built by Ron Crane that ran over a copper pair to the IMP at the medical school.  I did the driver work to connect the 11/34 to the smaller 11 running the NCP.

It is kind of funny to say “smaller” when the thing you are smaller than is an 11/34.

The other thing I remember about that system is that we had a version of “ed” with an added command
that was sort of like .-10,.+10p for displaying the local context.

By the time I graduated in 1981 we had an 11/70, which was just awesome.  With the split I and D space you could programs which were (or seemed to be!) enormous.

-L

[TUHS] PDP-11 questions

[Clem Cole]

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On Mon, Jan 25, 2016 at 8:38 AM, Lawrence Stewart <stewart at serissa.com>
wrote:

> We had one at the Stanford Information Systems Lab sometime in 78 or 79,
> running (I think) V7, and we certainly didn’t do the port ourselves!  We
> did put it on the Arpanet though, as SU-ISL.  This
> was a pretty weird hookup.  The NCP ran on a front-end LSI-11 (or was it
> an 11/23?) and there was
> a Very Distant Host interface home-built by Ron Crane that ran over a
> copper pair to the IMP at the medical school.  I did the driver work to
> connect the 11/34 to the smaller 11 running the NCP.
>

​If it was 78, it was probably v6+ of some sorts running Chesson's Arpanet
NCP from Illinois.​  UNIX/TS (aka V6+++ / pre V7) sorts of oozes out via
the Bell Labs' OYOC like Ted in '78 - that's what we ran at CMU since Ted
brought it with him. Its a heavily hacked V6 kernel and many of what would
become the v7 utilities including the a new compiler and the standard I/O
library.   Same was true of PWB 1.0 - which was based on most of the code.
   Dennis would not formally get V7 (which had an updated kernel) released
until mid '79 (FWIW: The date on a number of the files in the V7
distribution tapes in Warren's archives show Aug 1, '79 - which sounds
about right for when Dennis got it out).
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[TUHS] PDP-11 questions

[Dave Horsfall]

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On Mon, 25 Jan 2016, Clem cole wrote:

> Dave not doubt. Sorry. I didn't  publish.

Sorry; I wasn't accusing you.  It was a couple of bods at UNSW (if they're 
on this list then they know who they are).

But yeah, had I known of prior work then I certainly would have used it 
(with all due credit) instead of re-inventing that particular wheel.

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."

[TUHS] PDP-11 questions

[Clem Cole]

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On Tue, Jan 26, 2016 at 2:52 PM, Dave Horsfall <dave at horsfall.org> wrote:

>
> Sorry; I wasn't accusing you.
>

​no issues.

​

> But yeah, had I known of prior work then I certainly would have used it
> (with all due credit) instead of re-inventing that particular wheel.

​same here.  The UNIX community has always tended to do what they had to do
and shared as they could and when they knew about it.
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