The IBM System/360 Revolution

[Lynn Wheeler]

recent post in facebook groups:

The IBM System/360 Revolution

[Recorded April 7, 2004]

Computer pioneers and National Medal of Technology awardees Erich
Bloch, Fred Brooks, Jr. and Bob Evans with current IBM technology
chief Nick Donofrio discuss the extraordinary IBM System/360 project.

IBM launched the System/360 on April 7, 1964. Many consider it the
biggest business gamble of all time. At the height of IBM's success,
Thomas J. Watson, Jr. bet the company's future on a new compatible
family of computer systems that would help revolutionize modern
organizations. This lecture presents a behind-the-scenes view of the
tough decisions made by some of the people who made them, and
discusses how the System/360 helped transform the government, science
and commercial landscape.

Computer History Museum
https://www.youtube.com/@ComputerHistory
https://computerhistory.org/

old (archived) 24 Mar 2004 bit.listserv post of the event
http://www.garlic.com/~lynn/2004d.html#15 "360 revolution" at computer history museuam (x-post)

linkedin year old post about IBM "downfall", starting with Learson
trying(& fails) to block bureaucrats, careerists, MBAs from destroying
Watson Legacy
https://www.linkedin.com/pulse/john-boyd-ibm-wild-ducks-lynn-wheeler/
a couple decades later, IBM has one of the largest losses in US company
history and was being reorganized into the 13 "baby blues" in
preparation for breaking up the company.

[Lynn Wheeler]

Amdahl guote about design of 360 (from facebook group)

He said they identified at all the companies that had the recourses to
pay them lots of money. Then they went to these companies and asked
them what products/programs they would pay big money for. They
designed these programs and identified common services they all relied
upon and designed those services. Then they designed an OS that would
well support those services and programs. Then they designed a
customer support system. Then they designed the hardware to support
the OS, services, programs, and customer support.

[D.J.]

Post by Lynn Wheeler
Amdahl guote about design of 360 (from facebook group)
He said they identified at all the companies that had the recourses to
pay them lots of money. Then they went to these companies and asked
them what products/programs they would pay big money for. They
designed these programs and identified common services they all relied
upon and designed those services. Then they designed an OS that would
well support those services and programs. Then they designed a
customer support system. Then they designed the hardware to support
the OS, services, programs, and customer support.

Aha ! Lock those customers into software and hardware they need.

[Ahem A Rivet's Shot]

On Fri, 15 Sep 2023 11:23:56 -0500

Post by D.J.

Post by Lynn Wheeler
Amdahl guote about design of 360 (from facebook group)
He said they identified at all the companies that had the recourses to
pay them lots of money. Then they went to these companies and asked
them what products/programs they would pay big money for. They

Wow! Now that's commercialism at its purest.

Post by D.J.

Post by Lynn Wheeler
designed these programs and identified common services they all relied
upon and designed those services. Then they designed an OS that would
well support those services and programs. Then they designed a
customer support system. Then they designed the hardware to support
the OS, services, programs, and customer support.

They used the old system analyst's rulebook - clever!

1: Work out what the business needs to do
2: Decide what software can be used to support it
3: Pick hardware and OS to support that software

Post by D.J.
Aha ! Lock those customers into software and hardware they need.

IBM always were primarily about selling services (design,
support ...) the hardware and software were just the means to an end.

[Quadibloc]

Post by Ahem A Rivet's Shot
IBM always were primarily about selling services (design,
support ...) the hardware and software were just the means to an end.

Of course that made a lot of sense in the early days, where computers
were something newfangled, and companies that could benefit from
automating their accounting wouldn't necessarily find it easy to get
adequate in-house computer expertise.

John Savard

[Lynn Wheeler]

re:
http://www.garlic.com/~lynn/2023e.html#68 The IBM System/360 Revolution
http://www.garlic.com/~lynn/2023e.html#69 The IBM System/360 Revolution
and
http://www.garlic.com/~lynn/2023e.html#65 PDP-6 Architecture, was ISA

last year posts related to 50th anniv of VM/370 (after decision to add virtual memory to all 370s)
https://www.linkedin.com/pulse/zvm-50th-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50th-part-2-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50th-part-3-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50th-part-4-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50th-part-5-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50th-part-6-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50th-part-7-lynn-wheeler/
https://www.linkedin.com/pulse/zvm-50-part-8-lynn-wheeler/

I've mentiioned various times asked to tract down decision to add
virtual memory to all 370s. Found staff to executive making
decision. Basically MVT storage management was so bad that region sizes
frequently had to be specified four times larger than used. As a result
typical 1mbyte 370/165 only ran four regions concurrently, insufficient
to keep processor busy and justified. Moving MVT to 16mbyte virtual
memory (similar to running MVT in CP67 16mbyte virtual machine) allowed
number of concurrently running regions to be increased by factor of four
with little or no paging. Archived 2011 afc post with pieces of email
exchange
http://www.garlic.com/~lynn/2011d.html#73

Science center had joint project with Endicott to enhance CP67 virtual
machine support to support 370 virtual memory architecture ... and then
modify CP67 to run with 370 virtual memory (instead of 360/67 virtual
memory). My CP67L ran on the real 360/67, CP67H ran in virtual 360/67
(supporting 370 virtual machines), CP67I ran in virtual 370 (extra layer
not running CP67H on real hardware was because Cambridge system also had
professors, staff and students using the system, and wanted extra
security layer preventing unannounced virtual memory from leaking). This
was in regular use a year before before the 370 hardware (engineering
370/145) was operational with virtual memory support (and CP67I was used
for testing real hardware). Then three people from San Jose added 3330
and 2305 device support for "CP67SJ" (sometimes cp370) ... which was in
production use on internal 370 machines long before (and after) VM/370
operational.

In the morph from CP67->VM370, lots of CP67 features were dropped and/or
simplified. I then spent parts of 1974, adding CP67 (initially) into
VM/370 for CSC/VM (aka after joining IBM one of my hobbies was
production operating systems for internal datacenters). I would sometime
needle the MULTICS people on the 5th flr that at some point, I was
supporting more CSC/VM production internal systems than the total number
of MULTICS systems that ever existed (aka some of the MIT CTSS/7094
people went to 5th flr to do MULTICS, others went to the science center
on 4th flr and did internal network, virtual machine, invented)

science center posts
http://www.garlic.com/~lynn/subtopic.html#545tech

some recent posts mentioning CP67L, CP67H, CP67I, CP67SJ
http://www.garlic.com/~lynn/2023e.html#44 IBM 360/65 & 360/67 Multiprocessors
http://www.garlic.com/~lynn/2023d.html#98 IBM DASD, Virtual Memory
http://www.garlic.com/~lynn/2023.html#74 IBM 4341
http://www.garlic.com/~lynn/2023.html#71 IBM 4341
http://www.garlic.com/~lynn/2022h.html#22 370 virtual memory
http://www.garlic.com/~lynn/2022e.html#94 Enhanced Production Operating Systems
http://www.garlic.com/~lynn/2022e.html#80 IBM Quota
http://www.garlic.com/~lynn/2022d.html#59 CMS OS/360 Simulation
http://www.garlic.com/~lynn/2022.html#55 Precursor to current virtual machines and containers
http://www.garlic.com/~lynn/2022.html#12 Programming Skills
http://www.garlic.com/~lynn/2021k.html#23 MS/DOS for IBM/PC
http://www.garlic.com/~lynn/2021g.html#34 IBM Fan-fold cards
http://www.garlic.com/~lynn/2021g.html#6 IBM 370
http://www.garlic.com/~lynn/2021d.html#39 IBM 370/155
http://www.garlic.com/~lynn/2021c.html#5 Z/VM