Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site cornell.UUCP Path: utzoo!watmath!clyde!floyd!vax135!cornell!rej From: rej@cornell.UUCP (Ralph Johnson) Newsgroups: net.micro Subject: Re: IBM vs VAX/unix Message-ID: <6683@cornell.UUCP> Date: Fri, 2-Mar-84 10:22:39 EST Article-I.D.: cornell.6683 Posted: Fri Mar 2 10:22:39 1984 Date-Received: Sat, 3-Mar-84 22:05:51 EST References: <571@pucc-h> Organization: Cornell Univ. CS Dept. Lines: 51 Microcomputers CAN replace most uses of VAXen. Not all, of course, and I wouldn't want to replace a VAX with any number of PCs, but there are much more cost effective ways to provide VAX equivalent power than with a VAX. 68000 Unix systems are surprisingly powerful. I judge the Callan Unistar-100 to be about one fourth the speed of a VAX11/780 for long compiles. It is about 60% of a VAX for non-floating point computation intensive tasks. A 68000 with 2 or 4 Meg of memory is probably the cheapest way to run Lisp. The major problem with microcomputers is slow, small disks. The speed ratio of applications on the Callan to those on the VAX depends primarily on the amount of disk accesses that they require, since the Callan uses slow 5" winchesters. Given a fast network with large file servers, 68000s could compete with VAXen in every application that does not use floating point. The major advantage that microcomputers have is that each user can have his own machine. Every VAX user knows the "it's two in the afternoon and the load factor is too high" blues. A VAX may beat a Callan at 7 AM, but a Callan will get my job done faster at 3 PM. While one nroff job saturates a VAX, it takes 10 nroff jobs to saturate 10 microcomputers. (And the jobs will probably finish two to four times as quickly.) Two dozen VAXen with disks and other peripherals cost on the order of 2 to 5 million dollars. For two million dollars you can get 200 Callans at single quantity prices - the quantity discount will buy an ethernet and some file servers. A VAX can support any number of people if they are not doing anything, but even two or three nroff jobs will slow it markedly. Thus, if people are doing heavy computation, ten 68000 systems will provide more throughput and better response time for a VAX, for less money. Notice that I do not necessarily think that 68000s are the best micro or that Callan makes the best 68000 Unix computer. However, I do think that these alternatives provide more Unix power for the dollar than a VAX, thus any argument that some other micro is even more cost efficient is further argument for my case. One reason to get a VAX is to use some special piece of equipment or software. Eventually, array processors and graphics equipment will be interfaced to microcomputers, and the software will get ported to 68000s. For example, I said that 68000s were a more cost effective way to run Lisp than VAXen, but the various 68000 Lisp systems seem to be in various stages of being ported from the VAX right now; I don't know of any which is supposed to be ready for production use. A major problem with connecting lots of microcomputers together is that it requires lots of unwritten software. SUN is supposed to have a complete system soon, and there are a few systems like Appolo which are finished, but quite expensive. However, everything that I have said is true in theory, if not in practice. Ralph Johnson rej@cornell cornell!rej