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From: grege@gold.GVG.TEK.COM (Greg Ebert)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Math-coprocessors...just how good are they for day to day applications?
Keywords: math co-processors
Message-ID: <1228@gold.GVG.TEK.COM>
Date: 1 Aug 90 19:01:37 GMT
References: <13074@sun.udel.edu>
Distribution: usa
Organization: Grass Valley Group, Grass Valley, CA
Lines: 37


In article <13074@sun.udel.edu> sphilips@sun.udel.edu (Santosh S Philips) writes:
>Hi, 
>
>Just how much of an improvement can I expect from adding a math
>co-processor to a PC with a hard disk in terms of software like WordPerfect 5.1
>Freelance Plus (lots of graphics), graphic terminal emulation
>communications software and finally Kermit?
>
Zippo. Only matters in computationally-intensive stuff, like Mandelbrot-set
generators, unless Freelance Plus does 3-D image transformations.

>1. Will it help the Norton SI rating if the machine?

CI will improve.

>2. Are the available xxx87 co-processors interchangable with xxx86
>   machines running at the same clock speed? e.g. 10Mz xxx87 in 10Mz
>   xxx86

8086: only 8087
80286: 80287, possibly an 8087 if your hardware manual SPECIFICALLY states
      this. The 8087 and 80287 are NOT interchangeable.
80386: Depends. The (old) AST Premium/386 (20Mhz) had an 80287 socket. The
      80387 is in a 68 pin PGA, whereas the 8087 & 80287 are 40 pin DIPs.
      Newer machines will accomodate 80387's only (and maybe a Weitek ?).
80486: Gee, I hope you're not looking for an 80487 :-).

>3. Would it hurt to put a 10Mz co-processor in a 6Mz or 8Mz machine?
>   What about efficiency ... is any lost?
> 

Only your pocketbook suffers. Putting a faster coprocessor in a system will 
work, but it wont execute faster. Speed is a function of the system clock 
rate, not the individual components. I suppose you could buy a 10Mhz 
co-proc for a 6Mhz system, and upgrade your system at a later time 
and not have to buy another coprocessor.