Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site petrus.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!harvard!talcott!panda!genrad!decvax!tektronix!uw-beaver!cornell!vax135!houxm!ihnp4!mhuxn!mhuxr!ulysses!gamma!epsilon!zeta!sabre!bellcore!petrus!hammond From: hammond@petrus.UUCP (Rich A. Hammond) Newsgroups: net.arch Subject: Re: RISC and MIPS Message-ID: <446@petrus.UUCP> Date: Tue, 6-Aug-85 08:28:12 EDT Article-I.D.: petrus.446 Posted: Tue Aug 6 08:28:12 1985 Date-Received: Mon, 12-Aug-85 03:01:34 EDT References: <419@kontron.UUCP> <237@weitek.UUCP> <437@petrus.UUCP> <1432@peora.UUCP> Organization: Bell Communications Research, Inc Lines: 17 > >... The Berkeley RISC's have no absolute addressing mode ... > >I'll accept RISCs when I see one runnning 4.3 BSD faster than an 11/780. > > I would like to point out that the IBM 370 (usually considered > a CISC :-> ) doesn't have absolute addressing and that it only > has a displacement of 2**12 bytes. They seem to be able to get > some rather large operating systems, including UNIX, to run on > it. I never claimed it was impossible to get something running, I was more concerned with whether the RISC retains its speed advantage when faced with large amounts of absolute addressing. Perhaps a couple global registers used as base registers (ala IBM 360) would cover the commonly accessed global data structures (or a smart loader would pack most of them together). 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.