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From: Lynn Wheeler <lynn@garlic.com>
Newsgroups: comp.arch
Subject: Re: time-sharing history, Privilege Levels Below User
Date: Wed, 12 Jun 2024 11:54:55 -1000
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John Levine <johnl@taugh.com> writes:
> In any event, I'd find the second article I linked to, the VM history
> written by IBMers who were there, more credible than some random third
> party magazine. CMS really was written at the same time as CP, and
> they always intended them to work together as a time-sharing system.

Some of the MIT CTSS/7094 people went to the 5th flr to do Multics;
others went to the science center on the 4th flr to do virtual machines,
internal network, invent GML in 1969, other interactive applications.

cambridge science center wanted a 360/50 to add virtual memory to
.... but all the spare 360/50s were going to FAA ATC project ... and they
had to settle for 360/40. (virtual machine) CP/40 (running on bare
hardware using hardware virtual memory mods _ was developed in parallel
with CMS (running on bare 360/40). When CP/40 virtual machines was
operational, they then could run CMS in CP/40 virtual machines.

Melinda history
http://www.leeandmelindavarian.com/Melinda#VMHist
and CP/40
http://www.leeandmelindavarian.com/Melinda/JimMarch/CP40_The_Origin_of_VM370.pdf
my OCR from Comeau's original paper
https://www.garlic.com/~lynn/cp40seas1982.txt

CP/40 morphs into CP/67 when 360/67 standard with virtual memory becomes
available. I was responsible for OS/360 running on 360/67 (as 360/65),
univ shutdown datacenter on weekends and I had datacenter dedicated for
48hrs straight). CSC came out Jan1968 to install CP/67 (3rd install
after CSC itself and MIT Lincoln Labs) ,,, and I mostly played with it
during my weekend dedicated time. First couple months was rewritting
pathlengths for running OS/360 in virtual machine. Benchmark was OS/360
jobstream that ran 322secs on real machine. Started out 858secs in
virtual machine (CP67 CPU 534secs) .... after few months got CP67 CPU
down to 113secs. I then rewrite time-sharing system scheduling and
dispatching, page I/O and page replacement, I/O arm scheduling, etc.

I'v joked that original CP/67 scheduling delivered to univ (and I
completely replaced) ... looked a lot like Unix scheduling that I first
saw 15yrs later. Also 1st install at univ (jan1968) had CP67 source in
OS/360 datasets ... it wasn't until a few months later that they moved
source to CMS files. After I graduated and joined science center, one of
my hobbies was enhanced production operating systems for internal
datacenters.

CP-67
https://en.wikipedia.org/wiki/CP-67
CP/CMS
https://en.wikipedia.org/wiki/CP/CMS
History of CP/CMS
https://en.wikipedia.org/wiki/History_of_CP/CMS
Cambridge Scientific Center
https://en.wikipedia.org/wiki/Cambridge_Scientific_Center

when it was decided to add virtual memory to all 370s, it was also
decided to rewrite CP67 for VM370, simplifying and/or dropping lots of
features (also renaming Cambridge Monitor System to Conversational
Monitor System and crippling its ability to run on real machine).

1974, I start migrating lots of original CP67 stuff (lots that I had
done as undergraduate) to VM370 Release2 base for an enhanced internal
CSC/VM (including for world-wide online sales&marketing support HONE
systems).  Then in 1975 I upgrade to VM370 Release3 base and add the
CP67 multiprocessor support (one of the things dropped in CP67->VM370)
.... originally for US consolidated HONE complex so they could add 2nd
processor to each of their systems (all the US HONE systems had been
consolidated in Palo Alto, trivia: when FACEBOOK 1st moved into silicon
valley, it was into new bldg built next door to the former US
consolidated HONE datacenter).

-- 
virtualization experience starting Jan1968, online at home since Mar1970