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Message
From: "H. Peter Anvin" <hpa@z...>
Date: Thu, 25 Sep 2003 13:44:51 -0700
Subject: Re: [oc] Small CPU architectures
Kirill 'Big K' Katsnelson wrote:
>
> For example, I *loved* the PDP-11 instructions set. When after VAXen there
> arrived the first PC/XTs, I wondered what type of instruction set does that
> 8086 beast have. Oh my, I should not! When I found out, I was shocked by
> its complexity and irregularity. It was disgusting! It was awful! After
> a very regular PDP-11 instructions, seeing 8086 is not for the faint of
> heart!
>
> I think, for one, that it is one of the easiest-decodable CISC instruction
> sets possible. I looked for an FPGA implementation; besides one sold as
> a signle-board replacement for a PDP-11 (so it was the matter of necessity
> and not choice in their case) I found none at all!
>
> Anyway, it would be interesting to find out what kind of more or less
> open research is being made in this direction.
>
PDP-11 is hardly simple (simpler, perhaps, but hardly simple. A lot of
the extensions make it really ugly, in fact.) Personally, I have been
sketching a bit on a "nanoRISC" -- a small RISC microcontroller with the
goal of implementing it in as little FPGA area as possible.
I think RISC is the way to go for small size.
-hpa
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