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From: ching@amd.AMD.COM (Mike Ching)
Newsgroups: comp.sys.ibm.pc
Subject: Re: NOP
Message-ID: <4478@amd.AMD.COM>
Date: Fri, 25-Sep-87 16:18:25 EDT
Article-I.D.: amd.4478
Posted: Fri Sep 25 16:18:25 1987
Date-Received: Sun, 27-Sep-87 02:03:26 EDT
References: <2306@sphinx.uchicago.edu>
Reply-To: ching@amd.UUCP (Mike Ching)
Organization: Advanced Micro Devices
Lines: 15
Keywords: NOP

In article <2306@sphinx.uchicago.edu> cjdb@sphinx.uchicago.edu (Charles Blair) writes:
>
>In debugging code written in assembly-language, I notice that MASM
>periodically inserts NOP's in places where they don't appear in the
>source. I imagine this is done to slow down the processor, but how
>does MASM "decide" the appropriate circumstances?
>

More likely that these NOPs follow forward branches. MASM leaves
space for a 3-byte jump instruction during its first pass and fills
the third byte with a NOP if a two byte instruction is all that is
necessary. The NOPs are never executed and don't slow down the
processor.

mike ching