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From: Thomas Koenig <tkoenig@netcologne.de>
Newsgroups: comp.arch
Subject: Re: What is an N-bit machine?
Date: Thu, 28 Nov 2024 17:56:23 -0000 (UTC)
Organization: A noiseless patient Spider
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On 2024-11-28, John Dallman <jgd@cix.co.uk> wrote:
> In early computer designs, arithmetic registers were much longer than
> addresses, the classic examples being machines with 36-bit words and 15-
> to 18-bit addresses. 
>
> Large logical address spaces started with the IBM 360, which had 32-bit
> arithmetic registers and 32-bit address registers. You couldn't put
> 32-bits worth of physical memory in a machine for over a decade after it
> appeared, but it was allowed for in the architecture.

The original /360 had a 24-bit address space. The plan had been
to make it 32-bit clean, but some people didn't get the memo, reasulting
in a lot of hassle later on.