Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!apple!apple.com!desnoyer
From: desnoyer@apple.com (Peter Desnoyers)
Newsgroups: comp.arch
Subject: Re: Uses for unusual instructions
Message-ID: <5446@internal.Apple.COM>
Date: 28 Nov 89 17:27:12 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 27
References:<1743@l.cc.purdue.edu> <1989Nov27.173555.19673@fxgrp.fx.com>

In article <1989Nov27.173555.19673@fxgrp.fx.com> mikew@fxgrp.fx.com (Mike 
Wexler) writes:
> >cik@l.cc.purdue.edu (Herman Rubin) writes:
> >Soem time ago, I posted to this group certain instructions which are 
cheap
> >in hardware and expensive in software.  I wish to discuss these and give
> >partial examples; the full examples are too lengthy and would provide 
> >little insight.
> It sounds like some special purpose hardware might help solve your problems
>                                                               ^^^^
> more quickly. I propose an experiment: 
> 1. Design a CPU with these instructions added and one without(you might be
>    able to start with some kind of publicly available designs from a 
>    university project).
> 2. Modify your codes to take advantage of these instructions. Run your code
>    through a good simulator and see how much perfomance you gain.

alternately:
Assume that a memory-mapped I/O device exists that takes data in (and 
possibly instruction bits on the low-order address lines), implements your 
instructions, and can return results on the next memory read cycle. 
Simulate performance of your code with this hardware. If it gives you a 
big boost, implement it in a programmable chip and put it in your system.

                                      Peter Desnoyers
                                      Apple ATG
                                      (408) 974-4469


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