Article View: comp.arch
Article #22137Re: CISC Silent Spring
From: John R. Dudeck
Date: Sat, 03 Feb 1990 23:38
Date: Sat, 03 Feb 1990 23:38
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In article <35456@mips.mips.COM> mash@mips.COM (John Mashey) writes: >a 68040 @ 25Mhz to be faster than a SPARC @ 25Mhz? >(yes, I've seen the Motorola ads that show the 68040 to be 20 mips versus >a SPARC's 18.... :-) In my understanding of RISC vs CISC, you can't directly compare RISC MIPS against CISC MIPS, because the risc instructions are simple, whereas the cisc instructions are complex. It may take several risc instructions to perform one cisc instruction. Originally the trick was to get the several risc instructions to execute in less time than the one complex instruction. Now the tables are turned, because the cpu designers have figured out how to get the cisc chips to perform the complex instruction in the same clock cycle that the risc chip takes to perform the simple instruction... In a DEC Professional editorial I saw the expression CRISCO (complex risc) architecture to refer to this. -- John Dudeck "You want to read the code closely..." jdudeck@Polyslo.CalPoly.Edu -- C. Staley, in OS course, teaching ESL: 62013975 Tel: 805-545-9549 Tanenbaum's MINIX operating system.
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!polyslo!jdudeck From: jdudeck@polyslo.CalPoly.EDU (John R. Dudeck) Newsgroups: comp.arch Subject: Re: CISC Silent Spring Message-ID: <25cb6b65.702c@polyslo.CalPoly.EDU> Date: 3 Feb 90 23:38:13 GMT References: <3300098@m.cs.uiuc.edu> <771@sce.carleton.ca> <35456@mips.mips.COM> Reply-To: jdudeck@polyslo.CalPoly.EDU (John R. Dudeck) Organization: Cal Poly State University -- San Luis Obispo Lines: 16