Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!rutgers!labrea!decwrl!nsc!voder!apple!bcase From: bcase@apple.UUCP (Brian Case) Newsgroups: comp.lang.c,comp.arch Subject: Re: Was the 360 badly-designed? (was Re: Compatibility with EBCDIC) Message-ID: <1588@apple.UUCP> Date: Sun, 23-Aug-87 00:30:59 EDT Article-I.D.: apple.1588 Posted: Sun Aug 23 00:30:59 1987 Date-Received: Sun, 23-Aug-87 21:53:33 EDT References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp> Reply-To: bcase@apple.UUCP (Brian Case) Organization: Apple Computer Inc., Cupertino, USA Lines: 49 Xref: mnetor comp.lang.c:3849 comp.arch:1875 In article <1580@sol.ARPA> crowl@cs.rochester.edu (Lawrence Crowl) writes: >>will need VERY good arguments to over-ride 25 years (almost) of success. > Implementations of the 360 architecture have improved immensly. BUT NOT THE ARCHITECTURE. > >On the contrary, the leading edge of technology supports the 360 architecture. BUT NOT THE LEADING EDGE OF THE ART. >Some of the fastest scalar machines available are based on the 360. > >I am not necessarily stating that the 360 architecture was well-designed, but I >am saying the architecture has shown flexibility and adaptability for many >years. If you wish to say the 360 architecture is bad, you must show why its >adaptability is illusory. The 360 architecture has been implemented on The adaptability is not illusory. It is, however, bought at an extremenly high price. >machines spanning roughly two orders of magnitude in performance. It has gone >from physical memory to virtual memory. It supported a virtual machine long >before many other architectures did. On the contrary, the 360 (370) is (has been) more than an "almost" success. You are correct in stating that some of the fastest scalar machines are based on the 360 (370) architecture. But that does NOT mean anything. Take, for example, the EDGE 68010 implementation in six, huge, 256-pin PGA gate arrays. It is definitely a fast processor. The Amdahl 5860 and siblings are fast processors. However, those machines are, relative to recent offerings from a few sources, VERY expensive. They are compatible, yes, but painfully expensive. Within reason, it is possible to have fast implementations, virtual machine implementations, implementations; the trick is to have SMALL, CHEAP fast implementations, virtual machine implemenations, implementations. The MIPS Co. processor, SUN 4 processor, the Acorn RISC machine processor, the Am29000 processor, etc. have, at least, for some problems, performance equal to or greater than multimillion dollar machines, at prices orders of magnitude lower. The 360 (370) architecture was, for its time, perhaps not badly designed. However, its flaws, relative to the current state of the art, are readily apparent. If it were to be introduced today, most (at least most of the people *I* know who are concerned about such things) would call it a badly designed architecture. bcase