[TUHS] Research UNIX PDP 11/45

[TUHS] Research UNIX PDP 11/45

[Henry Bent]

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Hello all,

I asked this question in a different thread but it may have been bogged
down in other discussion so I figured it was worth asking again.

What was the hardware configuration of the 11/45 that Research used to
implement early UNIX?  This would be circa late 1972/earlty 1973.  I have
found numerous references to it being an early production 11/45, and I
assume that it had an RK05, but I cannot find any details about things like
memory size and other peripherals.

Since the only extant sources are for V1, which was as I understand only
run on a singular 11/20, and V5 by which time UNIX had spread it doesn't
seem possible to infer a hardware configuration from existing code.

-Henry

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[TUHS] Re: Research UNIX PDP 11/45

[Clem Cole]

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Henry - the infamous Ken and Dennis picture:
https://www.bell-labs.com/usr/dmr/www/ken-and-den.jpg show the 11/20's
display.  Their is a console display is hidden behind the right most ASR-33
[the console for the 11/20, I think], and Ken is typing to another
processor - it's either an 11/40 or 11/45, given the parts of the bezel
shown in the picture.   The picture also shows 2 RK's, 2 DEC Tape and a
Paper Tape read/punch, and the Tek display on the table.

The Fifth Edition tape the low.s and conf.c list an 11/40 with drivers for
the RK05, KL, DC serial, and the PPT unit.  The Sixth edition is the first
time we see mch40 and mch45. There is also a rkunix, rpunix and hpunix on
the distribution tape.  The l.s file shows KL, DEC Tape, 9-Track and RP04
drivers (but no DC-11s).   We also see Ken's "sysfix" to deal with the
separate I/D space.

So ... I'm would have suspected that the first 11/45 had an RP04 as well as
at least one RK05, a TM-11 with a 9-track, and the DEC Tape unit. The
amount of memory is, of course, unknown.  It was pretty expensive in those
days, but I would have expected they would have pushed it to the max
[256K].
ᐧ

On Mon, Jul 17, 2023 at 3:44 PM Henry Bent <henry.r.bent@gmail.com> wrote:

> Hello all,
>
> I asked this question in a different thread but it may have been bogged
> down in other discussion so I figured it was worth asking again.
>
> What was the hardware configuration of the 11/45 that Research used to
> implement early UNIX?  This would be circa late 1972/earlty 1973.  I have
> found numerous references to it being an early production 11/45, and I
> assume that it had an RK05, but I cannot find any details about things like
> memory size and other peripherals.
>
> Since the only extant sources are for V1, which was as I understand only
> run on a singular 11/20, and V5 by which time UNIX had spread it doesn't
> seem possible to infer a hardware configuration from existing code.
>
> -Henry
>

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[TUHS] Re: Research UNIX PDP 11/45

[Lars Brinkhoff]

Clem Cole wrote:
> The picture also shows 2 RK's, 2 DEC Tape and a Paper Tape read/punch,
> and the Tek display on the table.

As per Dennis' description Noel linked to, it's a DEC VT01A terminal
with a Tektronix 611 tube.  I found an old eBay photo online and copied
it to gunkies.  Bitsavers has a VT02 photo which is quite close.

https://gunkies.org/w/images/5/5d/VT01A.jpeg
https://bitsavers.org/pdf/dec/terminal/vt02/vt02_1.jpg


Noel Chiappa wrote:
> A good source is the Ken+Dennis picture:
>   https://www.bell-labs.com/usr/dmr/www/picture.html
> and the caption which Dennis wrote for it.

[TUHS] Re: Research UNIX PDP 11/45

[Noel Chiappa]

    > From: Henry Bent

    > What was the hardware configuration of the 11/45 that Research used to
    > implement early UNIX? .. I have found numerous references to it being
    > an early production 11/45, and I assume that it had an RK05, but I
    > cannot find any details about things like memory size and other
    > peripherals.

A good source is the Ken+Dennis picture:

  https://www.bell-labs.com/usr/dmr/www/picture.html

and the caption which Dennis wrote for it.

The image is not quite definitive, because there are two machines in that
bank of racks: a PDP-11/20, and a PDP-11/45 (mostly hidden behind the
right-hand Teletype), and it's not possible to say which of the two machines
the various peripherals are attached to.

But it seems to have had two RK03's (and an RK11 somewhere to drive them) and
an RF11 (no idea how many RS11 drives it had at that point),; a TU56 (and a
TC11 somewhere to drive that), and a PC05 (with PC11 controller boards).
(There are pages for all these things here:

  https://gunkies.org/wiki/Category:UNIBUS_Peripherals

which include links to the DEC documentation on them.)


I'm doing more searching, through documents I recall having additional
crumbs; let me go ahead and send this, and there will be a lengthy addendum
shortly.

	Noel

[TUHS] Re: Research UNIX PDP 11/45

[segaloco via TUHS]

> A good source is the Ken+Dennis picture:
> 
> https://www.bell-labs.com/usr/dmr/www/picture.html
>
> Noel

There is actually another photo from the same session:

https://computerhistory.org/wp-content/uploads/2019/10/102685442.03.01.jpg

From a higher angle too so you can see both the 20 and the 45 to its left there.  Not very much more to be gleaned from it but it does feature the bezels of both PDP-11s.

- Matt G.

[TUHS] Re: Research UNIX PDP 11/45

[Henry Bent]

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On Mon, 17 Jul 2023 at 18:52, segaloco via TUHS <tuhs@tuhs.org> wrote:

> > A good source is the Ken+Dennis picture:
> >
> > https://www.bell-labs.com/usr/dmr/www/picture.html
> >
> > Noel
>
> There is actually another photo from the same session:
>
> https://computerhistory.org/wp-content/uploads/2019/10/102685442.03.01.jpg
>
> From a higher angle too so you can see both the 20 and the 45 to its left
> there.  Not very much more to be gleaned from it but it does feature the
> bezels of both PDP-11s.
>
> - Matt G.
>

Nice!  I would assume that there would be no need to connect two TU56s to
one machine, so that does solve one aspect of this.

-Henry

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[TUHS] Re: Research UNIX PDP 11/45

[Angelo Papenhoff]

On 17/07/23, Noel Chiappa wrote:
> A good source is the Ken+Dennis picture:
> 
>   https://www.bell-labs.com/usr/dmr/www/picture.html

I asked ken about this once and he said it wasn't even their machines.


Angelo

[TUHS] Re: Research UNIX PDP 11/45

[Noel Chiappa]

    > From: Henry Bent

    > there will be a lengthy addendum shortly.

The most useful thing is probably this:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/low.s

which lists exactly what was there; not only the types, but how many of each
there are. This is from 'nsys', which is slightly before the actual V4, so
it's quite early. 'low.s' is inherently machine-specific; i.e. different
machines would share most kernel files identically, but _not_ this one -
unless they had _absolutely identical_ device sets. So this one is _probably_
the one from the /45 in picture.

It shows:

  RK11
  RF11
  PC11
  TC11
  TM11

  1xKL11
  12xDC11
  1xDP11	(synchronous serial)
  1xDN11	(dial-out asynch control)

  1xDR11C	(parallel port to -11/20)
  2xDC11	(Screw Works voice synthesizer)
  1xDR11A	(voice response unit)
  1xDR11C	(C/A/T typesetter)

(Line printer, card reader and RP11 are commented out; more about the RP11
in a later message.


There's also this:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/11-45

which is a bit hard to interpret, but I think might list what's in each rack:
the TC11, RK11 (early ones), RF11 and TM11 (early ones) were large custom
wire-wrapped backplanes which bolted into the front or back of a 19 inch
rack; this:

  https://gunkies.org/wiki/RK11-C_disk_controller

has an image of such an RK11. The "MOS 16-24" is probably a reference to an
MS11:

  https://gunkies.org/wiki/MS11_Semiconductor_Memory_System 

which had to mount in the CPU backplane. The "MM" entries are likely core
memory units; probably MM11-K's:

  https://gunkies.org/wiki/MM11-K_core_memory

since they seem to be 4KW each. (Maybe MM11-E's or 'F's, though; those are
also 4KW each.) I'm not sure what they "PL"s are - probably Plessey core?
Anyway,it looks like the machine had 104KB total.


This file:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/conf.c

lists all the types of devices on the machine. One oddity is that it lists
two RK11's; but if you look at the RK11 driver:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/dmr/rk.c

it's only set up to handle one physical controller. But there is this:

  #define	JRK	1	/* temp */

	if (bp->b_dev.d_major==JRK)
		d = bp->b_dev.d_minor;
	else
		d = bp->b_blkno%3;

so the two different major device entries appear to handle the same disks in
different ways ("d = bp->b_blkno%3" will spread a virtual drive across three
physical drives).


Memory, it would have been hard to say (UNIX even then sized memory at start
up) but then I found that '11-45' file. I also found a copy of the CACM
version of the UNIX paper:

  https://people.eecs.berkeley.edu/~brewer/cs262/unix.pdf

which says the machine had 144KB (so they had added 40KB more at that point).
(I seem to recall someone had scanned the SOSP version; I didn't save the
pointer, but if someone knows where it is, it would be interesting to look,
and see what it says - they seemed to update this paper on a regular basis -
the copy included with V6 talks about the -11/70.)

The system at that point had "a 1M byte fixed-head disk .. four moving-head
disk drives which each provide 2.5M bytes on removable disk cartridges, and
a single moving-head disk drive which uses removable 40M byte disk packs"

The RS11 disks for the RF11 were 512KB, so either they'd added a second one,
or switched to an RS04 (but that's a MASSBUS device). The big disk was an
RP03 so they had added an RP11, which wasn't present earlier.

	Noel

[TUHS] Re: Research UNIX PDP 11/45

[Jonathan Gray]

On Mon, Jul 17, 2023 at 08:49:46PM -0400, Noel Chiappa wrote:
>   https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/dmr/rk.c
> 
> it's only set up to handle one physical controller. But there is this:
> 
>   #define	JRK	1	/* temp */
> 
> 	if (bp->b_dev.d_major==JRK)
> 		d = bp->b_dev.d_minor;
> 	else
> 		d = bp->b_blkno%3;
> 
> so the two different major device entries appear to handle the same disks in
> different ways ("d = bp->b_blkno%3" will spread a virtual drive across three
> physical drives).

"Berkeley's 11/45 was among the first systems that Thompson had encountered
that had two disks on the same controller!"
Twenty Years of Berkeley Unix
https://www.oreilly.com/openbook/opensources/book/kirkmck.html

> Memory, it would have been hard to say (UNIX even then sized memory at start
> up) but then I found that '11-45' file. I also found a copy of the CACM
> version of the UNIX paper:
> 
>   https://people.eecs.berkeley.edu/~brewer/cs262/unix.pdf
> 
> which says the machine had 144KB (so they had added 40KB more at that point).
> (I seem to recall someone had scanned the SOSP version; I didn't save the
> pointer, but if someone knows where it is, it would be interesting to look,
> and see what it says - they seemed to update this paper on a regular basis -
> the copy included with V6 talks about the -11/70.)

tuhs/Applications/Dennis_Tapes/dmr_tapes.tgz
dmr_tapes/dmr2/tp/paper/p1 Nov 1973
"The PDP-11/45 on which our UNIX installation is implemented is a
16-bit word (8-bit byte) computer with 104K bytes of core memory;
UNIX occupies 42K bytes."

tuhs/Documentation/Papers/unix_cacm74.pdf July 1974
"The PDP-11/45 on which our UNIX installation is implemented is a
16-bit word (8-bit byte) computer with 144K bytes of core memory;
UNIX occupies 42K bytes."

tuhs/Distributions/Research/Dennis_v6/v6doc.tar.gz unix/p1 Jun 1975
"The PDP-11/45 on which our UNIX installation is implemented is a
16-bit word (8-bit byte) computer with 112K bytes of core memory;
UNIX occupies 53K bytes."

version from the Australian DECUS symposium (August 1977)
has the same line as as v6

tuhs/Documentation/Papers/BSTJ/bstj57-6-1905.pdf July/Aug 1978
"The PDP-11/70 on which the Research UNIX system is installed is a
16-bit word (8-bit byte) computer with 768K bytes of core memory;
the system kernel occupies 90K bytes about equally divided between
code and data tables."

v7/usr/doc/cacm/p1 matches bstj

[TUHS] Re: Research UNIX PDP 11/45

[Henry Bent]

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On Mon, 17 Jul 2023 at 20:49, Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:

>     > From: Henry Bent
>
>     > there will be a lengthy addendum shortly.
>
> The most useful thing is probably this:
>
>   https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/low.s
>
> which lists exactly what was there; not only the types, but how many of
> each
> there are. This is from 'nsys', which is slightly before the actual V4, so
> it's quite early. 'low.s' is inherently machine-specific; i.e. different
> machines would share most kernel files identically, but _not_ this one -
> unless they had _absolutely identical_ device sets. So this one is
> _probably_
> the one from the /45 in picture.
>
> It shows:
>
>   RK11
>   RF11
>   PC11
>   TC11
>   TM11
>
>   1xKL11
>   12xDC11
>   1xDP11        (synchronous serial)
>   1xDN11        (dial-out asynch control)
>
>   1xDR11C       (parallel port to -11/20)
>   2xDC11        (Screw Works voice synthesizer)
>   1xDR11A       (voice response unit)
>   1xDR11C       (C/A/T typesetter)
>
> (Line printer, card reader and RP11 are commented out; more about the RP11
> in a later message.
>
>
> There's also this:
>
>   https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/11-45
>
> which is a bit hard to interpret, but I think might list what's in each
> rack:
> the TC11, RK11 (early ones), RF11 and TM11 (early ones) were large custom
> wire-wrapped backplanes which bolted into the front or back of a 19 inch
> rack; this:
>
>   https://gunkies.org/wiki/RK11-C_disk_controller
>
> has an image of such an RK11. The "MOS 16-24" is probably a reference to an
> MS11:
>
>   https://gunkies.org/wiki/MS11_Semiconductor_Memory_System
>
> which had to mount in the CPU backplane. The "MM" entries are likely core
> memory units; probably MM11-K's:
>
>   https://gunkies.org/wiki/MM11-K_core_memory
>
> since they seem to be 4KW each. (Maybe MM11-E's or 'F's, though; those are
> also 4KW each.) I'm not sure what they "PL"s are - probably Plessey core?
> Anyway,it looks like the machine had 104KB total.
>
>
> This file:
>
>   https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/conf.c
>
> lists all the types of devices on the machine. One oddity is that it lists
> two RK11's; but if you look at the RK11 driver:
>
>   https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/dmr/rk.c
>
> it's only set up to handle one physical controller. But there is this:
>
>   #define       JRK     1       /* temp */
>
>         if (bp->b_dev.d_major==JRK)
>                 d = bp->b_dev.d_minor;
>         else
>                 d = bp->b_blkno%3;
>
> so the two different major device entries appear to handle the same disks
> in
> different ways ("d = bp->b_blkno%3" will spread a virtual drive across
> three
> physical drives).
>
>
> Memory, it would have been hard to say (UNIX even then sized memory at
> start
> up) but then I found that '11-45' file. I also found a copy of the CACM
> version of the UNIX paper:
>
>   https://people.eecs.berkeley.edu/~brewer/cs262/unix.pdf
>
> which says the machine had 144KB (so they had added 40KB more at that
> point).
> (I seem to recall someone had scanned the SOSP version; I didn't save the
> pointer, but if someone knows where it is, it would be interesting to look,
> and see what it says - they seemed to update this paper on a regular basis
> -
> the copy included with V6 talks about the -11/70.)
>
> The system at that point had "a 1M byte fixed-head disk .. four moving-head
> disk drives which each provide 2.5M bytes on removable disk cartridges, and
> a single moving-head disk drive which uses removable 40M byte disk packs"
>
> The RS11 disks for the RF11 were 512KB, so either they'd added a second
> one,
> or switched to an RS04 (but that's a MASSBUS device). The big disk was an
> RP03 so they had added an RP11, which wasn't present earlier.
>
>         Noel
>

Noel,
Thank you very much for this thoroughly researched and documented
explanation.  I hope that it will be of use to others as well.

-Henry

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