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From: quadibloc <quadibloc@gmail.com>
Newsgroups: comp.arch
Subject: Re: Why I've Dropped In
Date: Thu, 12 Jun 2025 15:00:04 +0000
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On Wed, 11 Jun 2025 17:05:13 +0000, Thomas Koenig wrote:

> What is the use case for having base and index register and a
> 16-bit displacement?

The IBM System/360 had a base and index register and a 12-bit
displacement.
Most microprocessors have a base register and a 16-bit displacement.

So this lets my architecture be a superset of both of them. Great
selling point, and thus I didn't think too hard about whether it is
"needed", because an architecture that instead tries to only provide
genuinely necessary capabilities...

now forces programmers, used to other systems that were more generous in
one way or another, to change their habits!

That would presumably spoil sales or ruin the popularity of the ISA.

John Savard