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From: Lynn Wheeler <lynn@garlic.com>
Newsgroups: comp.arch
Subject: Re: What is an N-bit machine?
Date: Thu, 28 Nov 2024 12:44:23 -1000
Organization: Wheeler&Wheeler
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jgd@cix.co.uk (John Dallman) writes:
> Apples and oranges. IBM had fewer but much larger customer organisations,
> and could not afford to upset them much. Most IBM mainframe shops write
> some software themselves; that wasn't the case for Apple users in the
> 1980s. 

Amdahl had won the battle to make ACS, 360 compatible, then when ACS/360
was canceled, he left IBM and formed his own 370 clone mainframe
company.
https://people.computing.clemson.edu/~mark/acs_end.html

Circa 1971, Amdahl gave talk in large MIT auditorium and somebody in the
audience asked him what justifications he used to attract investors and
he replied that even if IBM were to completely walk away from 370, there
was hundreds of billions in customer written 370 code that could keep
him in business through the end of the century.

At the time, IBM had the "Future System" project that was planning on
doing just that ... and I assumed that was what he was referring to
.... however in later years he claimed that he never had any knowledge
about "FS" (and had left IBM before it started).

trivia: during FS, internal politics was killing off 370 projects and
claims are the lack of new 370 products in the period is what gave the
clone 370 makers (including Amdahl) their market foothold. some more
info
http://www.jfsowa.com/computer/memo125.htm
when FS finally imploded, there was mad rush to get stuff back into the
370 product pipelines, including kicking off the quick&dirty 3033&3081
efforts.

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