Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uunet!gistdev!flint From: flint@gistdev.gist.com (Flint Pellett) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: Difference between 386/33 & 486/25 not counting fp Message-ID: <1163@gistdev.gist.com> Date: 8 Apr 91 18:19:51 GMT References: <1991Apr7.232112.20682@agate.berkeley.edu> Organization: Global Information Systems Technology Inc., Savoy, IL Lines: 45 c60b-1eq@web-1e.berkeley.edu (Noam Mendelson) writes: >In article dd2x+@andrew.cmu.edu (David Eugene Dwiggins) writes: >>Is there a significant difference in speed between a cached 33 Mhz system >>and a 486/25 system not counting floating point performance? >>David >Do you mean 33 MHz 386 vs. 25 MHz 486? If the 386 is cached, and you >don't include the math coprocessor, it should be equal or faster than the >486. Of course that depends on the size of the cache. >+==========================================================================+ >| Noam Mendelson ..!agate!ucbvax!web!c60b-1eq | "I haven't lost my mind, | >| c60b-1eq@web.Berkeley.EDU | it's backed up on tape | >| University of California at Berkeley | somewhere." | I sure hope people aren't basing buying decisions on the info presented so far in this string. A lot of the numbers are wrong: a 33 MHz 386 with cache is not the same as a 486. As someone who uses both a 386 AND a 486 machine daily, let me try to set some stuff straight: The 486 is a lot faster at everything: generally >2 times as fast, at the same clock speed. That means a 25 MHz 486 runs about half again faster than a 33 MHz 386. But anyone who looks only at CPU speed in determining overall system performance is foolish: the speed of your disks, the speed of your controller, the bus speed, the speed of your memory (wait states), the speed of your video adapter, it all matters. Unless you know what you are doing, even doubling one of these factors may have no noticable improvement in speed for a specific application: each different application will have it's own bottleneck. I have a 25 MHz 486 that uses 3 minutes to do a large C compile which takes 20 minutes to do on an uncached 20 MHz 386: both have the same amount of memory. If we pumped that 386 up to 33 MHz, it would be 1.65 times faster, and would still take > 12 minutes. If, by some miracle, we could get 1.5 times the performance through caching, it would still be taking 8 minutes. That 386 doesn't have nearly as good a disk controller, although the disk speeds are identical: my estimate is it would be 1.5 times faster with a better controller, which would mean it would take 5 minutes compared to the 3 the 486 uses. Does that sound equal to you? (Remember that software can make even more difference- when I don't use Micro-Slow's compiler, I get the compile done in under 2 minutes.) -- Flint Pellett, Global Information Systems Technology, Inc. 1800 Woodfield Drive, Savoy, IL 61874 (217) 352-1165 uunet!gistdev!flint or flint@gistdev.gist.com