Path: utzoo!utgpu!watserv1!ria!uwovax!baer From: baer@uwovax.uwo.ca Newsgroups: comp.sys.ibm.pc Subject: Re: Math chips and CAD was: recommendations wanted Message-ID: <4911.25ce0291@uwovax.uwo.ca> Date: 6 Feb 90 03:47:45 GMT References: <183@b8.INGR.COM> <4426@pegasus.ATT.COM> <25c86533:4479.2comp.sys.ibm.pc;1@vpnet.UUCP> <25ce13f4.5fd6@polyslo.CalPoly.EDU> Lines: 38 In article <25ce13f4.5fd6@polyslo.CalPoly.EDU>, jdudeck@polyslo.CalPoly.EDU (John R. Dudeck) writes: > In article <25c86533:4479.2comp.sys.ibm.pc;1@vpnet.UUCP> akcs.amparsonjr@vpnet.UUCP (Anthony M. Parson, Jr.) writes: >>will say an 80386 (25 mhz) without a coprocessor, is STILL faster by far >>than the 8088/8087 combination. Moral: get a fast 80286 or 80386, and >>possibly save the cost of buying a math coprocessor. Of course, it depends > > I haven't done any precise comparisons, but I watched a friend run Generic > CADD 2.0 on his 8mhz luggable XT with a 4 mhz 8087, and then tried running > the same thing on a Premium/286 10 mhz with no math chip. There was no > contest. The XT won easily. Now I have a 386/20, and I haven't had a chance > to do any comparisons. I also have a math chip. But I would be willing to > bet my money on the XT against a 386 with no math chip. > We did some timings on computationally intensive programs, with relatively little I/O, on three machines: 1) my 286 with an 8mHz math chip, 2) a grad student's machine, a 386, 25 mHz, with cache, no math chip, 3) the department's 386, 20 mHz, no cache, with a 387 chip (20mHz). (BTW, all machines have disk drives running at 28ms, but as I said, the programs involved relatively little I/O). The 286/287 combination "timed in" at about the same (perhaps 10% slower) as the 386/cache/no chip configuration. The 387/no cache/math chip configuration was 4-5 times faster. I understand that the Intel 387 chip is considerably faster than the 287 chip (even if we control for speed differences). This seems to bear this out. I have no timings on a 386sx-387sx combination, but I understand the 387sx chip is considerably faster than an equivalent 287 chip. [This implies that while a 16mHz 386sx machine may not be that much faster for most operations than a plain vanilla 12mHz 286, and perhaps even a bit slower than a 16mHz 286, if it has a 387sx chip it should be *much* faster than a 286-287 -- perhaps other newsgroup contributors might care to comment on this]. --------------------------------------------------------------------- Douglas Baer, Assoc. Prof., Dept. of Sociology, University of Western Ontario, London, Canada N6A 5C2 Internet: BAER@UWO.CA Bitnet: BAER@UWOVAX Telephone: [home] (519)-657-4799 *most reliable number [office] (519)-661-3859 [leave messages, M-F 9-4pm EST] (519)-661-3606