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From: halvers@italy.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: NOP
Message-ID: <7493@steinmetz.steinmetz.UUCP>
Date: Wed, 30-Sep-87 08:46:56 EDT
Article-I.D.: steinmet.7493
Posted: Wed Sep 30 08:46:56 1987
Date-Received: Sat, 3-Oct-87 04:22:11 EDT
References: <2306@sphinx.uchicago.edu> <4478@amd.AMD.COM> <309@ncrcan.UUCP>
Sender: root@steinmetz.steinmetz.UUCP
Reply-To: halvers@italy.UUCP (peter c halverson)
Organization: General Electric CRD, Schenectady, NY
Lines: 27
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.

Not in this case, since Mike was talking about NOP's padding
unconditional jump instructions, i.e.

        mov     bx,ax
        jmp     somewhere_else -----+
        nop <--- never reached      |
                                    v
next:   lea     addr

*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
Pete Halverson                       ARPA: halverson@ge-crd.ARPA
General Electric Company             UUCP: halvers@desdemona.steinmetz.UUCP
Corporate R & D                            halvers@desdemona.steinmetz.ge.com
Schenectady, NY

"Money for nothin' and your MIPS for free"