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From: John Levine <johnl@taugh.com>
Newsgroups: comp.arch
Subject: Re: The Design of Design
Date: Thu, 25 Apr 2024 22:13:33 -0000 (UTC)
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According to Stephen Fuld <SFuld@alumni.cmu.edu.invalid>:
>Thomas Koenig wrote:
>
>> John Levine <johnl@taugh.com> schrieb:
>> 
>> > They had the insight to see that the 16 fixed sizs registers could
>> > be in fast storage on high end machines, main memory on low end
>> > machines, so the high end machines were fast and the low end no
>> > slower than a memory-memory architecture which is what it in
>> > practice was. It was really an amazing design, no wonder it's the
>> > only architecture of its era that still has hardware
>> > implementations.
>
>Yes, although it isn't clear how much of its success is due to
>technical superiority versus marketing superiority.

S/360 invented eight bit byte addressed memory with larger power of 2
data sizes, which I think all by itself is enough to explain why it
survived. All the others, which were word or maybe decimal digit
addressed, died. Its addresses could handle 16MB which without too
many contortions was expanded to 2GB, a lot more than any other design
of the era. We all know that the thing that kills architectures is
running out of address space.

I thought the PDP-10 was swell, but even if DEC had been able to
design and ship the Jupiter follow-on to the KL-10, its expanded
addressing was a kludge. It only provided addressing 8M words or about
32M bytes with no way to go past that.

-- 
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly