Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!rutgers!usc!samsung!uunet!tronsbox!tron1
From: tron1@tronsbox.xei.com (HIM)
Newsgroups: comp.unix.sysv386
Subject: Math Co-procs
Message-ID: <276f6aae-1decomp.unix.sysv386@tronsbox.xei.com>
Date: 19 Dec 90 13:27:36 GMT
Lines: 49


Ok, I am probably pushing my luck here ...


I have established from many people that a 80287 in the 80386 MB I have will
be fine, and that interactive will "do the right thing".

Now, there are two types of 80287 , the 80287-10 and the 80287-XL. 

Since the 80287-XL claims a speed increase of like 400% over the 80287-10 I
looked it over and it said ...

     "Caution: Do not use the 80287-XL in 80386 based computers.
               Use only the 80287-10."

Wierd. So I called Intel and asked why.... the person there said that the
80287-XL was really a 80387 in a '287 carrier for the most part. It was much
faster because of this but that the 80386 CPU in my computer would wrongly
think it was a real 80387 and would just kinda stop dead. When asked, I was
assured that all the pins were compatible, and that no physical damage would
result from this un-holy union.

Now, the question.... many of the replies I got told me that the SysV math
code for using the math co-proc is really for the 80287 for compatibility
reasons. So this means that these are my questions...

1) Will it matter if the OS really did think it was a 80387 ? If it is
   really only gonna generate 80287 code then....

2) My BIOS only has a 80287 on/off register, does ISC check the chips or the
   to determin the FPU type ? (If the bios, then again, we will be ok).

3) Could a program with root priviledge go into the kernal and FORCE SET
   the 80287 flag if the 8037 flag gets set wrongly ?

See the problem ??

(And they told me trying the Perstore under unix was bizzare!)
(Look ! No net!)
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