Xref: utzoo comp.sys.ibm.pc.misc:10511 comp.sys.ibm.pc.hardware:9948 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!convex.csd.uwm.edu!anthony From: anthony@convex.csd.uwm.edu (Anthony J Stieber) Newsgroups: comp.sys.ibm.pc.misc,comp.sys.ibm.pc.hardware Subject: Re: DS HD floppies Message-ID: <13217@uwm.edu> Date: 18 Jun 91 20:52:27 GMT References: <1991Jun18.050747.26870@bronze.ucs.indiana.edu> Sender: news@uwm.edu Followup-To: comp.sys.ibm.pc Organization: University of Wisconsin - Milwaukee Lines: 33 In article <1991Jun18.050747.26870@bronze.ucs.indiana.edu> rschmidt@copper.ucs.indiana.edu (roy schmidt) writes: >Chris Genly writes: >> 1) Why can't I format a DS HD diskette as a DS DD disk? >> > The DS HD diskette uses a different type of medium for recording. It >is designed to hold a weaker magnetic "charge" for each bit written so Actually it's the reverse of that. HD disks of both sizes have a higher coercivity magnetic medium. This means the write current has to be higher, not lower. Trying to format a HD disk to DD may fail as the write current may not be high enough to write data reliably. Coercivity for 5.25" HD is about double that for DD. Try to format a DD disk as HD may fail as bit density is too high, and it lacks the coercivity to retain the magnetic field. In practice either can be swapped for the other, results will vary based on the drive and floppies used. In general, it's a good idea to not cross format HD and DD disks. I've only done it under duress. >> 2) Is there a slot or hole somewhere in the floppy jacket that tells >> the drive what capacity disk is inserted? > > Not on the 5-1/4" disks. The difference in medium is only important In recent years HD floppies almost never have a hub ring, will DD always do. In the past this was not true, so it's certainly possible to find a DD disk without a hub ring. As far as a I know, no drive can detect a hub ring. -- <-:(= Anthony Stieber anthony@csd4.csd.uwm.edu uwm!uwmcsd4!anthony Psion Mailing List subscriber submissions psion ----------\ the (human) moderator psion-owner -------+--@csd4.csd.uwm.edu subscriptions and file requests psion-request ----/