Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!brutus.cs.uiuc.edu!jarthur!elroy.jpl.nasa.gov!ames!vsi1!ubvax!weitek!jetsun!brothers From: brothers@jetsun.WEITEK.COM (bill brothers) Newsgroups: comp.sys.ibm.pc.programmer Subject: Re: How is a 68000 as fast as an 80386?? Message-ID: <885@jetsun.WEITEK.COM> Date: 7 Mar 90 22:21:26 GMT References: <505@bilver.UUCP> <6933@ucdavis.ucdavis.edu> <4451@cbnewsl.ATT.COM> Reply-To: brothers@weitek.COM (bill brothers) Organization: WEITEK, Sunnyvale CA Lines: 55 In article <4451@cbnewsl.ATT.COM> afg@cbnewsl.ATT.COM (andrew.goldberg) writes: >In article <6933@ucdavis.ucdavis.edu>, vmrad@pollux (Bernard Littau) writes: >> In article mark@acsdev.uucp (Mark Grand) writes: >> +In article <505@bilver.UUCP> alex@bilver.UUCP (Alex Matulich) writes: >> + >> + Naturally, I wanted more speed, so I ported the program to an AT&T 386WGS >> + at work, which is a 25 MHz 80386 IBM compatible. I compiled it using >> + Turbo C 2.0, large memory model. Then I watched in chagrined disbelief as >> + that number-crunching section still took about a minute to execute -- >> + actually a few seconds longer than my Amiga.... > > Actually, to me it sounds like you need a 32-bit compiler for > your 386. You are comparing an Amiga compiler that gets the most > out of the 68000 with a PC compiler that was not intended for > the 386. I use Microway's C compiler and see about a factor of > two improvement. There is also the Metaware HighC compilers which generate very good FP code. Using Microway or Metaware on highly intensive math stuff will generate much better speeds (even using the FP emulator). > > If you want more speed buy a Weitek chip, which the > AT&T 6386/25 will accept. The 25 MHz Weitek goes for about > $1300 and will give you another factor of 5 or so, if > you do not use transcendental functions. The Microway > C compiler, among others, supports the Weitek. Thanks for the mention Andy. BTW if anybody reading this is developing commercial products, call Weitek for information regarding our developer program. It offers significant discounts on products. {end of commercial} Again, don't forget Metaware... >> >> single to double, doing the calculation in double, and converting back >> to single. > > ?huh? While your comments about single vs. double are > right on the money, what's all this about C being a "poor Wellll.... except that both Microway and Metaware give you ways to prohibit the float promotion or use the ANSI control of what gets promoted to doubles. Most of the CAD/CAM people in the DOS world are now using one of these two compilers. > > Andy Goldberg ----- Bill Brothers ISV Support Specialist brothers@weitek.COM Voice (408) 738-8400 {sun,pyramid}!weitek.COM!brothers Compuserve: 73757,1443