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From: John Savard <quadibloc@servername.invalid>
Newsgroups: comp.arch
Subject: Re: Oops (Concertina II Going Around in Circles)
Date: Thu, 25 Apr 2024 12:41:23 -0600
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On Thu, 25 Apr 2024 16:00:14 +0000, mitchalsup@aol.com (MitchAlsup1)
wrote:

>In my opinion, your first cut at an ISA encoding should not consume more 
>than ½ of the available encodings. Concer-tina-tanic is already full to
>the brim and you are still just fleshing it out.

Basically, I think that the reasonable length that a computer
instruction should occupy is that which a similar instruction occupied
on the IBM System/360 - which, in its day, was not regarded highly for
its code density.

However, I have banks of 32 registers instead of 16, and 16-bit
displacements instead of 12 bits. Having only load and store
memory-reference instructions, of course, helps to make up for this.

That's why I can only use 8 of the 32 registers as base registers and
as index registers, too.

For wanting the impossible, of course I basically deserve what I get.
If I _could_ manaage to pull it off, of course, the result would be of
some practical use; an instruction set that's plain, clear, and simple
(at least when compared to monstrosities like Itanium and x86) and
which is parsimonious in its use of memory is of some value.

While I'm rearranging the deck chairs, maybe I'll come up with an
original idea.

John Savard