Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 8/28/84; site lll-crg.ARPA Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!houxm!whuxl!whuxlm!akgua!sdcsvax!dcdwest!ittvax!decvax!genrad!panda!talcott!harvard!seismo!umcp-cs!gymble!lll-crg!brooks From: brooks@lll-crg.ARPA (Eugene D. Brooks III) Newsgroups: net.arch Subject: Hypercubes Message-ID: <418@lll-crg.ARPA> Date: Wed, 27-Feb-85 00:27:08 EST Article-I.D.: lll-crg.418 Posted: Wed Feb 27 00:27:08 1985 Date-Received: Sun, 3-Mar-85 02:54:47 EST Distribution: net Organization: Lawrence Livermore Labs, CRG group Lines: 30 WARNING: Serious flames here! It really upsets me that an individual would claim that a bus architecture is better than a Hypercube when the first thing he does in his argument is give the bus a 300 megabyte a second bandwidth and give the hypercube the equivalent of 9600 baud serial lines to communicate with. If you need that kind of edge to prove your point you are in DEEP TROUBLE. In the Caltech project the communication speed of each channel was on par with the floating point speed as it should be in numerical applications work. If the floating point speed of a node is 10MFLOPS, as it is for current high cost/performance ratio hardware these days, the communication channels should support a transfer rate to match. For those who wish compare the Hypercube to the x, xy, xyz, (or xyxt....) bus Just what do you think a hypercube is? Its a xyzt... bus with the number optimized. Just two cpus connect to each bus (the word bus is used loosely here) What is better? Nothing! For those who want to complain that a Cube of order=20 would require each processor to manage 20 messages on average being a bad thing there is of course a better way to build the hardware if this is a problem. The problems to which the Cube has been put to in the past used only communication with neighboring processors and rather straightforward maps of the problem onto the machine. If your problems are of a sort that require random addressed message fordwarding then you need to consider the alternate (and more expensive) hardware design. There is the old adage "You get what you pay for." In fact you probably should be considering a shared memory machine. Perhaps even a Hypercube!