Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!princeton!udel!rochester!cornell!batcomputer!pyramid!voder!apple!baum From: baum@apple.UUCP Newsgroups: comp.arch Subject: Re: Wirth's challenge (was Re: RISC) Message-ID: <6900@apple.UUCP> Date: Fri, 4-Dec-87 15:37:01 EST Article-I.D.: apple.6900 Posted: Fri Dec 4 15:37:01 1987 Date-Received: Tue, 8-Dec-87 03:47:33 EST References: <902@mips.UUCP> <1775@cognos.UUCP> <5157@columbia.edu> Reply-To: baum@apple.UUCP (Allen Baum) Organization: Apple Computer, Inc. Lines: 39 -------- [] >In article <1047@winchester.UUCP> mash@winchester.UUCP (John Mashey) writes: >Sorry, I meant absolutely no hint that proprietary info got moved, >and I did mean in spirit, especially of methodology of starting with >serious optimizing compiler technology and doing substantial analysis. >It is extremely interesting that there was no influence from the >March 1982 Radin paper at ASPLOS; I would have thought that it would have >been analyzed thoroughly at least for confirmation of direction, >but I wasn't there, so I believe you. > >Certainly, it is interesting that both 801 and Spectrum used >optimizing compiler-driven design, >32 registers, >32-bit instructions, >separate I&D caches, >and no windows. >(MIPS can't be included as independent: we certainly had access to the >published 801 documents before we started.) > >Either the similarities arise from the limited choices once you've >made some of those decisions, or, starting from some of the same assumptions, >and proceeding with realted methodologies, you get to somewhat similar >designs. [There are of course all sorts of little differences amongst >the 3 machines mentioned, but if you take the universe of RISC machines, >they look more similar than most.] I think you hit it right on the head. We did indeed use the ASPLOS papers for confirmation of our intuition & measurements, but they only confirmed, so nothing got changed. We did see some differences, but we liked our approach (for better or worse), so no differences there either. We did have a chance to consider register windows, since the RISC I papers were published by then, but decided that for future implementations, the large register file, and its decoding would be a bottleneck (impact critical path), and that smart register allocation would be sufficient. -- {decwrl,hplabs,ihnp4}!nsc!apple!baum (408)973-3385