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Path: utzoo!utgpu!water!watmath!clyde!feg
From: feg@clyde.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: NOP
Message-ID: <14606@clyde.ATT.COM>
Date: Wed, 30-Sep-87 09:27:04 EDT
Article-I.D.: clyde.14606
Posted: Wed Sep 30 09:27:04 1987
Date-Received: Fri, 2-Oct-87 00:40:15 EDT
References: <2306@sphinx.uchicago.edu> <4478@amd.AMD.COM> <309@ncrcan.UUCP>
Organization: AT&T Bell Labs, Whippany, NJ
Lines: 21
Keywords: NOP
Summary: Was posting carefully read?

In article <309@ncrcan.UUCP>, brian@ncrcan.UUCP (Brian Onn) writes:
> In article <4478@amd.AMD.COM> ching@amd.UUCP (Mike Ching) writes:
> >.... The NOPs are never executed and don't slow down the
> >processor.
> >
> >mike ching
> 
> Sorry, but the NOPS are always executed (how would the processor know that
> it is in fact a NOP, if it didn't execute it) and each execution takes 
> a finite, albeit minimal amount of execution time.

True enough, IF the processor executes the NOP. However, what was discussed
was the substitution by the assembler of a two byte unconditional jmp for
the three bytes set aside on pass 1. Obviously, the processor never gets
to execute the NOP in such a case.





Forrest Gehrke