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> Organization: Storage Dimensions, Inc. Message-ID: <1991Jun03.185623.11956@xstor.com> Date: Mon, 03 Jun 91 18:56:23 GMT In article 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.