Re: XL series chips

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Article #20564

#20564

From: rkc
Date: Tue, 28 Mar 1989 18:04

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> mahar@weitek.UUCP (Mike Mahar) says:
>  They [XL chipset] are used in imbedded systems mostly so they don't have much impact
>  on the UNIX world. It is popular with computer graphics people and it is the
...
Part of the reason the XL chips haven't affected the UNIX world is because the
chips don't correctly separate User and Supervisor Mode.  The "backing
registers" that are reserved for supervisor mode use can be accessed from user
mode.  Weitek's Support Staff currently suggests that application users be
given assembly manuals with the man page for the SWAP instruction (which
accesses those registers) removed.  The chips are quite fast; but this is a
big flaw.
	-Rob

PS.  Don't read this if you're an applications programmer for these chips.

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ll-xn!rkc
From: rkc@XN.LL.MIT.EDU (rkc)
Newsgroups: comp.arch
Subject: Re: XL series chips
Message-ID: <1332@xn.LL.MIT.EDU>
Date: 28 Mar 89 18:04:49 GMT
Organization: MIT Lincoln Laboratory, Lexington, MA
Lines: 14