Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!fernwood!uupsi!dorsai!skipm
From: skipm@dorsai (Dorsai SysOp)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Two IDE questions
Message-ID: <i7Js33w163w@dorsai>
Date: 31 May 91 06:14:17 GMT
References: <1991May14.052800.26878@ux1.cso.uiuc.edu>
Organization: The Dorsai Diplomaitc Mission (+1.212.431.1944)
Lines: 25

phil@ux1.cso.uiuc.edu (Phil Howard KA9WGN) writes:
> 
> How does one tell the difference?
> 
> And how many different encoding systems, or other things, are relevant?
> Is ESDI its own encoding system?
> -- 

 
IDE drives are unique in that they allow you to flexibly determine what
their drives, heads, and cylinders are. While the drive physically has
a set number of heads and cylinders, you can set your BIOS to something
else that is equal to or less than a drive of the same size. For
example, a type 40 & type 17 drive look the same to an unformatted IDE
drive since neither of those configurations exceed the total megabyte
capacity of the drive. Note however, once you format them with a 
particular BIOS setting, the drive parameters are no longer interchangable
since information has been written to the drive on what it supposed to
"look like".
 
IDE drives do NOT use true MFM encoding, they use a subset of it, long
ago reffered to as MMFM by Zenith Corp, a technology used by them in
their early laptops.
 
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