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Path: utzoo!utgpu!water!watmath!watcgl!watmum!smvorkoetter
From: smvorkoetter@watmum.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: NOP
Message-ID: <1901@watcgl.waterloo.edu>
Date: Wed, 30-Sep-87 08:54:13 EDT
Article-I.D.: watcgl.1901
Posted: Wed Sep 30 08:54:13 1987
Date-Received: Fri, 2-Oct-87 06:34:24 EDT
References: <2306@sphinx.uchicago.edu> <4478@amd.AMD.COM> <309@ncrcan.UUCP>
Sender: daemon@watcgl.waterloo.edu
Reply-To: smvorkoetter@watmum.waterloo.edu (Stefan M. Vorkoetter)
Organization: U. of Waterloo, Ontario
Lines: 24
Keywords: NOP

In article <309@ncrcan.UUCP> brian@ncrcan.UUCP () 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.

I believe what Mr. Ching means is that NOPs after a jump are never
executed.  Thus, if you have an unconditional jump followed by a NOP
like:
		jmp	foo
		nop
	bar:	more-instructions

Then the NOP after the jump will never be executed since there is no
way to get to it.

Stefan Vorkoetter
Symbolic Computation Group
University of Waterloo