Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!rutgers!mailrus!iuvax!pur-ee!hankd
From: hankd@pur-ee.UUCP (Hank Dietz)
Newsgroups: comp.arch
Subject: Re: Architecture Wars, again; survey
Summary: Predictions -- will new CISC designs be a success?
Message-ID: <9725@pur-ee.UUCP>
Date: 9 Nov 88 15:18:34 GMT
References: <7316@winchester.mips.COM> <75478@sun.uucp> <10770@cup.portal.c <7809@winchester.mips.COM>
Organization: Purdue University Engineering Computer Network
Lines: 34

In article <7809@winchester.mips.COM>, mash@mips.COM (John Mashey) writes:
...
> 4. Will there be any successful new CISC architectures?
...
> 4. No.*

I don't agree.  There are two kinds of new CISC architectures which we can
reasonably expect to continue to be successful in the future:

1.	New CISC designs which embed execution mode(s) for compatibility
	with existing machine(s).  For example, the Vax had a pdp11 mode and
	the 386 really doesn't look much like an 8086 except in that it can
	pretend to be one.  Note that compatibility in this form is very
	much like having two processors in one, which is easy in microcode
	but....  (I'd rather see people performing static code analysis and
	transformation to make old code run on new hardware, but there will
	*always* be somebody who doesn't believe in that.)

2.	Special-purpose processors.  For example, it might be kinda neat to
	have IMSL microcoded so that each subroutine is an instruction...
	I'm not saying that an appropriate RISC machine couldn't run IMSL
	just as well, but rather that the cost & packaging of the
	special-purpose CISC processor can reach a rather large market.

On this second note, I wonder how long it will be before everyone realizes
that a CISC = RISC + ROM program?

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