Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!amdcad!rpw3
From: rpw3@amdcad.AMD.COM (Rob Warnock)
Newsgroups: comp.arch
Subject: Re: Software Distribution
Message-ID: <22778@amdcad.AMD.COM>
Date: 30 Aug 88 08:09:06 GMT
References: <1988Aug23.180420.28483@utzoo.uucp> <958@esunix.UUCP> <1988Aug29.202603.13897@utzoo.uucp>
Reply-To: rpw3@amdcad.UUCP (Rob Warnock)
Organization: [Consultant] San Mateo, CA
Lines: 27

There are a number of companies out there these days who have made major
advances in the art of emulation of one CPU on another, particularly when
the emulated CPU is the IBM PC (of some flavor). These products do a variety
of things (some products do one or more), including: (1) pre-processing of
the to-be-emulated program; (2) straight emulation, but with caching of the
"instruction decode" step; (3) detection of basic blocks and optimization and
caching of the whole basic block; (4) [other things I don't know about...?].
When running the emulator on, say, a Mac or Sun workstation the emulated
speed can exceed the native speed of a PC/AT.

The thought occurs that if one designed a virtual "machine" that was
specifically easy to emulate -- given these modern techniques -- that
this *might* be a suitable form for "portable" object programs (as
contrasted with some "universal intermediate form"). At least it bears
some thought.

(Hmmm... how hard is it for each of the current RISC CPUs to emulate each
of the others?)


Rob Warnock
Systems Architecture Consultant

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