ft0d+@andrew.cmu.edu (Feichin Tschang) (05/31/91)
Has anyone out there got any comments on using a 80287 math coprocessor with a 386-25 or similar? I believe my system board accommodates a 287 and they're about 1/4 the price of 387's, so my question is whether or not the 287 improves performance within a factor of using a 387 on a 386 system. Thanks for any replies.
chao@oahu.cs.ucla.edu (Chia-Chi Chao) (05/31/91)
ft0d+@andrew.cmu.edu (Feichin Tschang) writes: >Has anyone out there got any comments on using a 80287 math coprocessor with >a 386-25 or similar? I believe my system board accommodates a 287 and they're >about 1/4 the price of 387's, so my question is whether or not the 287 improves >performance within a factor of using a 387 on a 386 system. Yes, 287 does improve FP performance, but of course, not as high as 387. The only problem I have encountered is with the shareware version of Eureka which I downloaded recently. The documentation says that improperly clocked coprocessor may cause crashes, and I got crashes when I ran the program with 287 enabled. The Intel coprocessor test, however, ran without any problem. -- Chia-Chi Chao chao@cs.ucla.edu ..!ucbvax!cs.ucla.edu!chao
schuster@panix.uucp (Michael Schuster) (05/31/91)
In article <kcFHEYy00Uh7I20VVh@andrew.cmu.edu> ft0d+@andrew.cmu.edu (Feichin Tschang) writes: >Has anyone out there got any comments on using a 80287 math coprocessor with >a 386-25 or similar? I believe my system board accommodates a 287 and they're >about 1/4 the price of 387's, so my question is whether or not the 287 improves >performance within a factor of using a 387 on a 386 system. Support for the 80287 was dropped with the D stepping of the 80386. For sure your 386-25 is a D step or later. So a 287 probably wouldn't work, regardless of the motherboard manufacturer's ignorance of that fact. -- Mike Schuster | CIS: 70346,1745 NY Public Access UNIX: ...cmcl2!panix!schuster | MCI Mail, GENIE: The Portal (R) System: schuster@cup.portal.com | MSCHUSTER
marshall@wind55.seri.gov (Marshall L. Buhl Jr.) (06/01/91)
ft0d+@andrew.cmu.edu (Feichin Tschang) writes: >Has anyone out there got any comments on using a 80287 math coprocessor with >a 386-25 or similar? I believe my system board accommodates a 287 and they're >about 1/4 the price of 387's, so my question is whether or not the 287 improves >performance within a factor of using a 387 on a 386 system. Back years ago, I bought several of the original Compaq 386's. That was before the invention of the 387. They came with a socket for an 8MHz 287. We later got a Compaq 386 with a 387. We put 12MHz 287 daughter cards from Microway into the 287 sockets (they had their own clock). We found that the 16 MHz 387 was 2.5 times faster than the 12 MHz 287 when running floating point intensive FORTRAN programs. If you're doing a lot of math, you'd be better off spending a few hundred extra on the 387. Marshall -- Marshall L. Buhl, Jr. EMAIL: marshall@seri.gov Senior Computer Engineer VOICE: (303)231-1014 Wind Program 1617 Cole Blvd., Golden, CO 80401-3393 Solar Energy Research Institute Solar - safe energy for a healthy future
kai@kaiki.toppoint.de (Kai Voelcker) (06/03/91)
ft0d+@andrew.cmu.edu (Feichin Tschang) writes: > Has anyone out there got any comments on using a 80287 math coprocessor with > a 386-25 or similar? I believe my system board accommodates a 287 and they'r > about 1/4 the price of 387's, so my question is whether or not the 287 improv > performance within a factor of using a 387 on a 386 system. > > Thanks for any replies. I have one of the early 386 boards, so I could only use a 287. But I took the IIT 2C87. This chip runs at full clock and is Soft compatible to 387. And this combination is up to factor 2 faster than a 287. ________________________________________________________________________ | Kai Voelcker, Kappelner Str 18, D-2300 Kiel 1, voice: +49 431 335605 | | kai@kaiki.toppoint.de interests: 386asm, c, pascal; OR algorithms | | > PLEASE NOTICE: I must PAY for incoming mail! ($ 0.25/KB) Thanks. < | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~