[TUHS] Re: Research UNIX PDP 11/45

[Jonathan Gray <jsg@jsg.id.au>]

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