Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!ginosko!uunet!portal!cup.portal.com!Will
From: Will@cup.portal.com (Will E Estes)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Bug With Version IV of '386 Chip?
Message-ID: <23087@cup.portal.com>
Date: 14 Oct 89 06:44:15 GMT
References: <22957@cup.portal.com>
Organization: The Portal System (TM)
Lines: 49

Well, here's the scoop on the bug with the '386 chip from Intel.  Still
doesn't explain my problem, but it does give more information on the
problem in general:
Date:  13-Oct-89 09:46 PDT
From:  >CSI:@INTEL
Subj:  386 bug
To:     Will Estes
        Gary Brown
        Joe Beauchamp
        Russ Niklos
        Carl Rock
From:   Bob Albers @INTEL
Subj:   386 D-0 step CHMOS-IV pipelined bus mode bug
        During what should have been a routine shrink of the 386DX from
CHMOS-III to CHMOS-IV a new bug was introduced that affects the ability
of the 386 to operate correctly in pipelined bus mode. The bug only exists
when the on-chip paging unit is enabled AND address pipelining is enabled on
the external bus AND some other exotic conditions are also true. Most users
Enter command or <CR> for more!
EasyPlex
will not see the problem because most DOS software does not use paging; also
most higher speed 386 designs don't enable pipelining because they have an
external cache memory which makes pipelining unnecessary and more difficult
to implement. All 386 board vendors were notified about this erratum by
December, 1988 at the latest and had the option to disable pipelining
on their boards or to buy the CHMOS-III version. Please refer to the list
below to determine the version of the 386 that you have in your system.
Definitions:    CHMOS-III       1.5 micron CMOS process
                CHMOS-IV        1.0 micron CMOS process
                D-0 step        Version on CHMOS-III process
                                does NOT have pipeline bug.
                                Version on CHMOS-IV process
                                has pipeline bug.
                D-1 step        Version on CHMOS-IV process
                                that fixes pipeline bug.
                386DX-25  IV    CHMOS-IV D-0 step
                SX133           <--has pipeline bug
                386DX-25        CHMOS-III D-0 step
                SX215           <--some older yet identical units
                                <--were without an S#
                                <--never had pipeline bug
                386DX-25  IV    CHMOS-IV D-1 step
                SX218           <--pipeline bug fixed
        Since the message posted by Will Estes indicated that his board
was changed from an SX218 to an SX215 CHMOS-III part I'm confused. There
are no known errata or spec differences between these two versions.
The CHMOS-IV parts are generally faster though and this could have
caused a marginal board design to become flakey with one version or
another.