*BSD News Article 8365


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From: sastdr@torpid.unx.sas.com (Thomas David Rivers)
Newsgroups: comp.unix.bsd
Subject: Re: [386bsd] installing fpu (ULSI) results in floating exceptions
Message-ID: <ByJIpL.69w@unx.sas.com>
Date: 30 Nov 92 17:46:32 GMT
References: <6440@tuegate.tue.nl> <1992Nov30.013413.1119@ponds.uucp> <1992Nov30.060552.7912@kithrup.COM>
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In article <1992Nov30.060552.7912@kithrup.COM> sef@kithrup.COM (Sean Eric Fagan) writes:
>In article <1992Nov30.013413.1119@ponds.uucp> rivers@ponds.uucp (Thomas David Rivers) writes:
>>  1) The ULSI chip does *not* provide 80287 instructions (as the Intel
>>      and Cyrix chips do)
>
>Uh... are you sure you mean 80287?  Remember that the 80387 is a proper
>superset of the '287.
>
>-- 
>Sean Eric Fagan  | "we will probably just crash immediately; but at least
>sef@kithrup.COM  |  we will have written less code."
>-----------------+                 -- Chris Torek (torek@ee.lbl.gov)
>Any opinions expressed are my own, and generally unpopular with others.


  Yes, apparently the definition ULSI followed doesn't strictly imply
 superset.  That's the flaw.  

  That is, we all _know_ that the '387 is a superset of the '287, and
 that '287 instructions should work with a '387; but ULSI didn't know
 that...  Their chip only implements the strictly '387 instructions.
 (I don't know what these strictly '387 instructions are, what is/isn't
  implemented... seems strange to me.)

  This was according to Roland at ULSI.

  Again, should the chip encounter any unrecognized instruction; it will
 demonstrate this random behaviour.

	- Dave Rivers -
	(rivers@ponds.uucp (home))
	(sastdr@unx.sas.com (work))
-- 
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