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From: jay@splut.UUCP (Jay Maynard)
Newsgroups: comp.sys.ibm.pc,comp.unix.xenix
Subject: Re: A question about 80287s vd 80387s.
Message-ID: <48@splut.UUCP>
Date: Thu, 13-Aug-87 07:45:50 EDT
Article-I.D.: splut.48
Posted: Thu Aug 13 07:45:50 1987
Date-Received: Sun, 16-Aug-87 12:03:57 EDT
References: <1927@Shasta.STANFORD.EDU>
Organization: Confederate Microsystems, League City, TX
Lines: 30
Keywords: 80287 80387 math coprocessors
Summary: Well, PCTJ says it's faster...
Xref: mnetor comp.sys.ibm.pc:6776 comp.unix.xenix:607

In article <1927@Shasta.STANFORD.EDU>, boesch@Shasta.STANFORD.EDU (Brian Boesch) writes:
> I asked a salesman at PC-limited (Their machine only supports 80287) 
> and he says they get 90% of the performance of a 387 for a lot less cost.
> 
> Is the only difference between the 387 and 287 a few percent of
> speed up (I assume from a wider buss interface)?
> 
> Do the 80287 and 80387 take the same commands? and is software compiled 
> for one executable on the other?

In the August 1987 issue, PC Tech Journal says that its floating point
benchmark ran over 6 times faster on a Compaq Deskpro 386 than it did on a
PC/AT at 8 MHZ with a 287. 

Since the AT-series runs the 287 at 2/3 the main processor clock speed
(don't ask me why), the 287 in the tested AT ran at 5.33 MHz. That makes the
16 MHz 387 do things about twice as fast as a 287 for equivalent clock
speeds.

I don't know whether to attribute the speedup from the 287 to the 387 to a
wider bus interface or not, but it appears to be markedly faster anyway.

Note, though, that you pay a price for the speed: the 387 is going for
>$700, while even an 8 MHz 287 is still in the $275 range.

-- 
>splut!<...Jay Maynard, K5ZC | uucp: ...!seismo!soma!uhnix1!sugar!splut!jay
"Don't ask ME about Unix...  | GEnie: JAYMAYNARD            (...e-i-e-i-o!)
I speak SNA!"                | CI$: 71036,1603   FidoNet: SysOp @106/64
The opinions herein are shared by neither of my cats, much less anyone else.