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From: John Savard <quadibloc@servername.invalid>
Newsgroups: comp.arch
Subject: Re: Oops (Concertina II Going Around in Circles)
Date: Wed, 08 May 2024 20:39:09 -0600
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On Wed, 8 May 2024 21:59:54 +0000, mitchalsup@aol.com (MitchAlsup1)
wrote:

>May I suggest that sacrificing 16-bit instructions may give you the room
>whereby typical applications require less space without the 16-bit insts
>that with them !?!

Your suggestions are always welcome, given your great breadth of
knowledge.

My latest "extreme encoding position" means that 16-bit instructinos
are now relegated to a secondary instruction format that must be
indicated by a header. However, now they're 17 bits long instead of 15
bits long, so they can operate on any two registers in a 32-register
bank.

Having 14 instructions in a block instead of 8 instructions normally
lets me do more. I know that in your MY 66000 architecture, the
instructions have extra functionality that lets you combine things
like negation and increment with an operation. While I certainly could
try to add such a feature to my architecture - in fact, I did try that
in one Concertina II iteration - I'm afraid that, not having your
knowledge, I wouldn't be able to do it in a way that resulted in any
significant savings in the number of instructions required for a
program.

And if I tried to add flexibility, I'd end up with an instruction set
that looked like that of the VAX 11/780, which is not a direction to
go in if performance is a concern.