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From: veit@borneo.gmd.de (Holger Veit)
Newsgroups: comp.os.386bsd.development
Subject: 386 w/o V86? (was Re: More Details on the 386BSD Release 1.0 CD-ROM)
Date: 25 May 1994 16:19:16 GMT
Organization: GMD - German National Research Center for Computer Science
Lines: 41
Distribution: world
Message-ID: <2rvtq4$dha@omega.gmd.de>
References: <jmonroyCq1qK0.5vJ@netcom.com> <1994May25.040649.28711@njitgw.njit.edu> <jmonroyCqCrwC.L5K@netcom.com> <2rvq8a$9h7@inews.intel.com>
NNTP-Posting-Host: mururoa.gmd.de
Changed the subject, because it really does not have any bit to do with the old one.
In article <2rvq8a$9h7@inews.intel.com>, mwilley@pcocd2.intel.com (Mark Willey - PCD) writes:
|>
|> In article <jmonroyCqCrwC.L5K@netcom.com>, jmonroy@netcom.com (Jesus Monroy Jr) writes:
|> > Nakata Ken (CS major) (kxn3796@hertz.njit.edu) wrote:
|> > : "The Virtual Machine subsystem" "not available on all 386 chips"?
|> > : What *exactly* are you referring to, by "the Virtual Machine
|> > : subsystem"?
|> > :
|> > Please read the i386 data guide.
|>
|> I think he's referring to the "Virtual 8086 Environment". (ie running virtual
|> mode under protected mode -- not real mode)
|>
|> * But the question still is: Which Intel 80386 chips do not have virtual mode?
Today, they all have, but it is possible that some early versions of the chip
had bugs concerning this mode, that reduced their usability w.r.t. v86 mode.
The notorious 'Single Sigma' chip comes to mind, but this was a bug related to
32 bit operability.
However, it is usually not Intel's policy to document bugs of their processors
in the official data sheets, so you should exactly cite where you have found
you assumption, Jesus (or shut up! The last time, with DMA/refresh, it required
the net several weeks to find out that you incorrectly based your assumptions on
an outdated schematic of the original IBM AT in the IBM TechRefManual, remember that?)
Second: if there were bad chips delivered that time which didn't operate correctly
in protected and related modes, it is unlikely that they would have survived
several generations of EMM386, DPMI, VCPI, and Windows software under DOS. No
need to care about buggy processors, there are more severe problems on some
PC boards.
--
Dr. Holger Veit | INTERNET: Holger.Veit@gmd.de
| | / GMD-SET German National Research | Phone: (+49) 2241 14 2448
|__| / Center for Computer Science | Fax: (+49) 2241 14 2342
| | / Schloss Birlinghoven | Had a nightmare yesterday:
| |/ 53754 St. Augustin, Germany | My system started up with
| ... Booting vmunix.el ...