Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!husc6!hao!ames!oliveb!pyramid!prls!mips!mash From: mash@mips.UUCP Newsgroups: comp.arch Subject: Re: RISC Survey Articles Message-ID: <820@winchester.UUCP> Date: Thu, 22-Oct-87 01:43:18 EDT Article-I.D.: winchest.820 Posted: Thu Oct 22 01:43:18 1987 Date-Received: Sat, 24-Oct-87 21:10:39 EDT References: <3119@sol.ARPA> <6457@apple.UUCP> <216@bernina.UUCP> Reply-To: mash@winchester.UUCP (John Mashey) Organization: MIPS Computer Systems, Sunnyvale, CA Lines: 46 In article <216@bernina.UUCP> tve@bernina.UUCP (Th. von Eicken) writes: >In article <6457@apple.UUCP> bcase@apple.UUCP (Brian Case) writes: >>I have a personal problem with Multinovic's article because it >>confuses the Am29000 and the Am29300 family...... >But if that only were the only bug! >_ The MIPS-CO processor should be called MIPS-R2000 so that it doesn't get > confused with the Stanford MIPS project. Yes, that would help. >_ The paragraphs on interlocks are questionnable: what are "stated software > interlocks"? The software reorganization needed in MIPS, MIPS-X and > MIPS-R2000 are quite different I think. There are differences, but the fundametnals are quite similar. >_ The MIPS-R2000 pipeline is quoted for complexity, I think the 6 stage > CRISP pipeline with the decoded I-cache in the middle and operand > forwarding from virtually every stage to every other is somewhat more > complex. (No good/bad judjement intended here ...) Yep, CRISP is probably more complex. One of the issues omitted from the paper is that of tightly-coupled coprocessor interfaces, a topic that is, for example, critical to good FP performance. (For example, the MIPS R2010 FPU has a 6-stage pipeline to go with the R2000's 5....) >_ I like table 4 though. Converting Mhz into ns cycle times is fun! And > what was the story about MIPS? It was very hard to figure out what the MIPS numbers meant in that column. They had us (MIPS R2000) listed at 16.7MHz for 8 MIPS, which doesn't make any sense at all, since @ 12.5MHz we average 8 conservative-real-program-not-dhrystone-vax(vms/ultrix usually)-mips, and @ 16.7MHz 10-12 of those mips, depending on memory system. A bunch of the rest of the numbers seem pretty weird, either higher or lower than makes sense. (AMD is lower, CRISP seems a little higher, Spectrum higher.) A few of the numbers have imputed accuracy levels beyond reason (10.8 MIPS for Spectrum? can you tell the difference between that and 11 MIPS?) Despite all of this, it's at least good to see somebody trying to put together surveys on this information, some of which is not easy to get. -- -john mashey DISCLAIMER: UUCP: {decvax,ucbvax,ihnp4}!decwrl!mips!mash OR mash@mips.com DDD: 408-991-0253 or 408-720-1700, x253 USPS: MIPS Computer Systems, 930 E. Arques, Sunnyvale, CA 94086