Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!microsoft!leefi
From: leefi@microsoft.UUCP (lee fisher)
Newsgroups: comp.sys.ibm.pc
Subject: Re: distinguishing between MS and IBM(PC) DOS
Message-ID: <51020@microsoft.UUCP>
Date: 20 Feb 90 04:26:54 GMT
References: <6178@uhccux.uhcc.hawaii.edu> <8526@ingr.com> <25c5ed3d:4260.6comp.sys.ibm.pc;1@vpnet.UUCP>
Organization: Microsoft Corp., Redmond, WA
Lines: 15

I don't have any DOS technical references handy, but I believe that the
system service which returns the DOS version has a register or two that
points to the OEM number (I believe it was a byte, thus 0-255). I don't
believe that all OEMs change this number, but it might help you identify
between some different OEM flavors of DOS. If I recall from the IBM PC-DOS
techincal reference, their version set that byte to 00h. Again, this is
hazy info, but I believe that Packaged Product MS-DOS set this byte to FFh,
and other OEMs could opt to set it to some other value in between. Like I
said, this is with no references handy and with fuzzy knowledge. But since
people are just talking about spawning the VER command, I thought that this
might be of interest to the person that originally asked this question...
--
lee fisher, leefi@microsoft.uucp, leefi@microsoft.wa.com
{uw-beaver,decvax,decwrl,fluke,intelca,sco,sun,uunet}!microsoft!leefi 
disclaimer: my opinions are not necessarily those of my employer.