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From: feustel@netcom.UUCP (David Feustel)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Mixing hard drive types: ESDI, MFM, IDE
Message-ID: <16597@netcom.UUCP>
Date: 10 Nov 90 23:39:29 GMT
References: <9011101215.aa16378@ICS.UCI.EDU>
Organization: DAFCO - An OS/2 Oasis
Lines: 12

IDE drive controllers usually respond to the IO address reserved for
the standard AT mfm (read WD1003) controller; hence an IDE controller
cannot coexist with the mfm controller unless one of the controllers
has been set to respond to the alternate hard disk io address.
Unfortunately, dos doesn't know about the alternate io address, so
whichever controller is setup for it can't be used in dos.

ESDI and SCSI controllers typically respond to a different set of io
address than the AT mfm addresses; therefore  they can coexist with
the mfm OR IDE controller.
-- 
David Feustel, 1930 Curdes Ave, Fort Wayne, IN 46805, (219) 482-9631