Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!pt.cs.cmu.edu!b.gp.cs.cmu.edu!ralf
From: ralf@b.gp.cs.cmu.edu (Ralf Brown)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Replacing an 80386 with an 80486
Message-ID: <8264@pt.cs.cmu.edu>
Date: 3 Mar 90 01:21:02 GMT
References: <29108@amdcad.AMD.COM> <1640057@hpspcoi.HP.COM> <9830@sequoia.UUCP> <1304@watserv1.waterloo.edu> <9729@portia.Stanford.EDU>
Organization: Carnegie-Mellon University, CS/RI
Lines: 20

In article <9729@portia.Stanford.EDU> dhinds@portia.Stanford.EDU (David Hinds) writes:
}    During task switches, the 386 saves its own context, but does not
}automatically save the floating point processor's context.  It generates
}an interrupt at the first floating point operation following a task switch,
}so the system software can handle switching 387 contexts.  As this feature
}was not present in the 80286, OS/2 probably doesn't know about it.  OS/2

Certainly it was present in the 286.  From the Intel 286 Programmer's 
Reference:

	The context of a processor extension (such as the 80287 numerics
	processor) is not changed by the task switch operation. ... The
	80286 detects the first use of a processor extension after a task
	switch by causing the processor extension not-present exception
	(#7) if the TS bit is set. (page 11-5)
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