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From: wilker@gauss.math.purdue.edu (Clarence Wilkerson)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: IBM AT & DTC 5287 & 3.5 inch (1.44) drives
Message-ID: <4583@mentor.cc.purdue.edu>
Date: 26 Jan 91 17:56:30 GMT
References: <1991Jan26.163545.27685@news.cs.indiana.edu>
Sender: news@mentor.cc.purdue.edu
Reply-To: wilker@gauss.math.purdue.edu.UUCP (Clarence Wilkerson)
Organization: Purdue University, West Lafayette
Lines: 15

I don't know anything about the DTC 5287.
In general on an AT, the Hard DISK and Floppy disk routines
are in the AT bios itself, no on the disk controller board.
If this is the case for the DTC, then there is no address to
go to for low level boards. That's a feature found on XT type
controller boards. If there is a ROM bios on board it's  
to allow sector translation from RLL's 26 sectors/track to the
MFM 17 sectors/track. My WD controllers do this with a jumper
on the board. That's also an issue for doing the formatting of
the hard drive, since none of the std. AT drive type have 26
sectors/track.
  If there is a ROM with useful routines, I'd look around
C800:000X, where X varies from one manufact. to another.
For WD it's 5.
Clarence Wilkerson