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From: prem@crackle.amd.com (Prem Sobel)
Newsgroups: comp.arch
Subject: Re: Complex Instructions
Message-ID: <25384@amdcad.AMD.COM>
Date: 24 Apr 89 19:09:49 GMT
References: <57252@yale-celray.yale.UUCP> <4101@tolerant.UUCP> <134@dg.dg.com> <39609@think.UUCP>
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Reply-To: prem@crackle.amd.com (Prem Sobel)
Organization: Advanced Micro Devices, Inc. Sunnyvale CA
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Many years ago, there was a machine called the Interdata Model 70 which
had instructions for atomically adding or removing items from circular
double ended queues. The data structure was defined reasonable effeciently
and the machine was microcoded.

Yet no one, no compiler seriously used these instructions. The reason was,
amazingly, that individual instructions were faster!!! I never looked at
the microcode, so I cannot commebnt why that was.


Prem