Xref: utzoo comp.lang.c++:2178 comp.lang.c:14498 comp.lang.forth:714 comp.lang.fortran:1583 comp.lang.misc:2270
Path: utzoo!utgpu!watmath!clyde!att!rutgers!mit-eddie!bu-cs!purdue!decwrl!labrea!csli!gandalf
From: gandalf@csli.STANFORD.EDU (Juergen Wagner)
Newsgroups: comp.lang.c++,comp.lang.c,comp.lang.forth,comp.lang.fortran,comp.lang.misc
Subject: Re: Assembly or ....
Message-ID: <6660@csli.STANFORD.EDU>
Date: 2 Dec 88 21:01:22 GMT
References: <1388@aucs.UUCP> <729@convex.UUCP> <1961@crete.cs.glasgow.ac.uk> <1988Nov29.181235.23628@utzoo.uucp> <960@vsi.COM>
Reply-To: wagner@arisia.xerox.com (Juergen Wagner)
Organization: Center for the Study of Language and Information, Stanford U.
Lines: 17


 In article <960@vsi.COM> friedl@vsi.COM (Stephen J. Friedl) writes:
 >In article <1988Nov29.181235.23628@utzoo.uucp>, henry@utzoo.uucp (Henry
 >Spencer) writes:
 >> Alas, if you buy your newer faster CPUs from Motorola or Intel, they can't
 >> tell you how many cycles each instruction takes!
 >
 >Why is this?
 >...

Because of instruction prefetching, overlapping of instruction executions, ...
The time an instruction takes to execute depends on its context.
Strictly speaking, e.g. a 68020 is not a von-Neumann machine!

-- 
Juergen Wagner		   			gandalf@csli.stanford.edu
						 wagner@arisia.xerox.com