Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site mips.UUCP Path: utzoo!linus!decvax!decwrl!Glacier!mips!mash From: mash@mips.UUCP (John Mashey) Newsgroups: net.arch Subject: Re: RISC and MIPS Message-ID: <163@mips.UUCP> Date: Sat, 10-Aug-85 18:28:22 EDT Article-I.D.: mips.163 Posted: Sat Aug 10 18:28:22 1985 Date-Received: Mon, 12-Aug-85 23:14:39 EDT References: <419@kontron.UUCP> <27800052@uiucdcs> Organization: MIPS Computer Systems, Mountain View, CA Lines: 32 > >> Anyway, the RISC claims will always be slightly dubious to me until I >> actually see a machine performing as claimed in a real situation. >> Hidden gotchas have a way of getting missed in paper exercises. >> /* End of text from uiucdcs:net.arch */ > > You probably won't have to wait TOO long since Acorn computer co. of > England just announced (in Electronics magazine) that they have good, > working die, the first time, after only 18 months of effort by 4 > people. The machine is able to sustain 3 of its MIPS and running > real programs (code produced by compilers) was "about 2 times a VAX > 11/780" and 10 times an IBM PC-AT. The article did not mention anything > about memory management, so they may or may not be winning because of > the lack of translation..... > .... True, we should not count our > RISCs before they are hatched, but there are real advanteges to RISC. 1) Real advantages to RISC : yes. 2) lack of memory management: unless one is just interested in a point product with a fairly narrow performance range, one must be exceedingly careful in memory management design for RISC, or you rapidly discover that you get a chip OK for controllers or unprotected systems, and near-useless for reasonable multi-tasking operating systems. 3) (Opinion, perhaps quite biased): it's pretty easy to do a RISC that's 2X a 780. What's harder, but necessary, is to figure out how the same chip architecture gets you to 5X, and soon 10X in a reasonable way; just running the clock faster doesn't do it. -- -john mashey UUCP: {decvax,ucbvax,ihnp4}!decwrl!mips!mash DDD: 415-960-1200 USPS: MIPS Computer Systems, 1330 Charleston Rd, Mtn View, CA 94043