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From: Lynn Wheeler <lynn@garlic.com>
Newsgroups: comp.arch
Subject: Re: third system syndrome, interactive use, The Design of Design
Date: Wed, 08 May 2024 07:58:52 -1000
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John Levine <johnl@taugh.com> writes:
> According to MitchAlsup1 <mitchalsup@aol.com>:
>>> TSS was a disaster due to an extreme case of second system syndrome,
>>> but Michigan's MTS and IBM skunkworks CP/67 worked great.
>>
>>TSS at CMU was extensively rewritten in assembly and became quite
>>tolerable--hosting 30+ interactive jobs along with a background
>>batch processing system. When I arrived in Sept 1975 it was quite 
>>unstable with up times less than 1 hour. 2 years later it would run
>>for weeks at a time without going down.
>
> For reasons I do not want to try to guess, AT&T did the software
> development for the 5ESS phone switches in a Unix system that sat on
> top of TSS. After IBM cancelled TSS, AT&T continued to use it as some
> sort of special order thing. At IBM there were only a handful of
> programmers working on it, by that time all quite experienced, and I
> hear that they also got rid of a lot of cruft and made it much faster
> and more reliable.
>
> At the same time, IBM turned the skunkworks CP/67 into VM/370 with a
> much larger staff, leading to predictable consequences.

TSS/360 was decommitted and group reduced from 1100 to 20. Morph of
TSS/360 to TSS/370 was much better (with only 20 people).

Both Amdahl and IBM hardware field support claimed they wouldn't support
370 machines w/o industrial strength EREP. The effort to add industrial
strength EREP to UNIX was many times the effort to do 370 port. They did
a stripped down TSS/370 with just hardware layer and EREP (called SSUP)
with UNIX built on top. IBM AIX/370 and Amdahl UTS were run in VM/370
virtual machines ... leveraging VM/370 industrial EREP.

CP/40 was done on 360/40 with virtual memory hardware mods; it morphs
into CP/67 when 360/67 standard with virtual memory became available.
Group had 11 people (1/100th TSS/360).

When I graduate and join IBM, one of my hobbies was enhanced production
operating systems for internal datacenters. With the decision to
add virtual memory to all 370s, it was decided to do VM/370 and some
of the science center people move to the 3rd flr taking over the
IBM Boston Programming Center for VM/370 group. The group was
expanding to 200+ and outgrew the 3rd flr, moving to the vacant IBM SBS
bldg out in Burlington Mall (of rt128).

Note the morph of CP67->VM370 dropped and/or simplified a bunch of
features (including multiprocessor support). In 1974, I started
migrating a bunch of CP67 stuff to VM370 R2. I had also done automated
benchmarking system and was the the 1st thing I migrated ... however,
VM370 couldn't complete a full set of benchmarks w/o crashing ... so the
next thing I had to migrate was the CP67 kernel synchronization &
serialization function ... it order for VM370 to complete benchmark
series. Then I started migrating a bunch of my enhancements.

For some reason AT&T longlines got an early version of my production
VM370 CSC/VM (before the multiprocessor support) ... and over the years
moved it to latest IBM 370s and propogated around to other
locations. Then comes the early 80s when next new IBM was 3081 ... which
was originally a multiprocessor only machine. The IBM corporate
marketing rep for AT&T tracks me down to ask for help with retrofitting
multiprocessor support to old CSC/VM ... concern was that all those AT&T
machines would migrate to the latest Amdahl single processor (which had
about the same processing as aggregate of the 3081 two processor).


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