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From: mitchalsup@aol.com (MitchAlsup1)
Newsgroups: comp.arch
Subject: Re: What is an N-bit =?UTF-8?B?bWFjaGluZT8=?=
Date: Thu, 28 Nov 2024 19:02:26 +0000
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On Thu, 28 Nov 2024 17:56:23 +0000, Thomas Koenig wrote:

> 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.

BAL -> BAS , ...

And assembly people using the upper 8-bits of base registers for
"interesting" things.