Newsgroups: comp.sys.ibm.pc.hardware
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!xstor!bills
From: bills@xstor.com (Bill Smith)
Subject: Re: Two IDE questions
References: <1991May14.052800.26878@ux1.cso.uiuc.edu> <i7Js33w163w@dorsai>
Organization: Storage Dimensions, Inc.
Message-ID: <1991Jun03.185623.11956@xstor.com>
Date: Mon, 03 Jun 91 18:56:23 GMT

In article <i7Js33w163w@dorsai> skipm@dorsai (Dorsai SysOp) writes:
>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.
> 
>Skip
MFM drives can also be used with smaller head or cylinder entries. I have
done this many times.

-- 

     =====================================================================
     Bill Smith, UNIX Technical Support           uucp:  uunet!xstor!bills
     Storage Dimensions, Inc.			        
