Xref: utzoo comp.sys.ibm.pc.misc:10527 comp.sys.ibm.pc.hardware:9963 Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!zaphod.mps.ohio-state.edu!think.com!snorkelwacker.mit.edu!bloom-picayune.mit.edu!athena.mit.edu!pshuang From: pshuang@athena.mit.edu (Ping-Shun Huang) Newsgroups: comp.sys.ibm.pc.misc,comp.sys.ibm.pc.hardware Subject: Re: DS HD floppies Message-ID: Date: 19 Jun 91 01:06:34 GMT References: Sender: news@athena.mit.edu (News system) Organization: Massachusetts Institute of Technology Lines: 38 In-Reply-To: chris@genly.UUCP's message of 16 Jun 91 17:24:17 GMT You've gotten a good bunch of replies. More comments: In article chris@genly.UUCP (Chris Hind Genly) writes: > The two types of floppies appear identical to the eye. That's not quite true, at least not with the diskettes which I have experience with (specifically, most of them are either brand name or from the mail order company MEI). If you hold them up so that light glares across the disk surface, you can see that the high density disks have a bluish tinge and are a lighter color than the brownish double-density floppies. I would disagree with in that a HD should be able to be formatted as a DD. Since the two kinds of disks are made with different materials with different magnetic coercivities, you can neither format a high-density to low-density nor low-density to high density. The low-density drive is *NOT* indifferent to the medium. Like you, I have had no success getting my (Teac) low-density drive to format high-density medium. Also, I think a high-density drive uses a more powerful but also more focused magnetic flux in its heads, not less. is incorrect about HD diskettes being preformatted, because they are not, unless you pay through the nose for the special ones which have been. The DOS-FORMAT program as a general rule does not check the disk to see what density it is; it only checks the BIOS for the drive type and any relevant command line switches. (This can be verified with one of several TSR DOS function snoopers, which show DOS calling the BIOS format disk option with the appropriate number of sectors for the format selected without ever reading from the disk.) Many third-party replacements for FORMAT.COM, such as the ones which come with Norton or with PC-Tools, have a quick-format option which does always format a floppy which already been previously formatted to the same capacity. With this option, they do not do true formatting at all, but merely wipe the directory and the FAT tables for the diskette. -- Singing off, UNIX:/etc/ping instantiated (Ping Huang)