Xref: utzoo comp.sys.ibm.pc.misc:10473 comp.sys.ibm.pc.hardware:9929 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!balrog!ctron.com From: dj@ctron.com (DJ Delorie) Newsgroups: comp.sys.ibm.pc.misc,comp.sys.ibm.pc.hardware Subject: Re: DS HD floppies Message-ID: <1675@balrog.ctron.com> Date: 18 Jun 91 11:52:40 GMT References: Sender: news@balrog.ctron.com Reply-To: dj@ctron.com Followup-To: comp.sys.ibm.pc Organization: None whatsoever Lines: 46 Nntp-Posting-Host: bragi In article , chris@genly.UUCP (Chris Hind Genly) writes: > 1) Why can't I format a DS HD diskette as a DS DD disk? The HD drive lays down two skinny tracks where the DD drive lays down one fat one. The DD drive isn't capable of erasing the two skinny HD tracks, as it misses one. This left over track does interfere with the read operation, as it's close enough to the head for that. You can reformat HD floppies as DD if you bulk erase them first, to erase all the skinny HD tracks. For this same reason, a 360K floppy written with a 1.2M drive cannot be reliably read on a 360K drive, as the track written is too skinny for the fat DD head in the drive. And a 360K floppy formatted with a 360K drive cannot be reliably written with a 1.2M drive, as the HD head is too skinny to erase the fat DD track. > 2) Is there a slot or hole somewhere in the floppy jacket that tells > the drive what capacity disk is inserted? Only on 3.5" floppies. The presence of the hole indicates a 1.44M disk. > 3) What are the various diskette formats available now, and what > are thier capacities? 8" : Your guess is as good as mine, but I think some of the 5.25" formats are supported. 5.25" : 160 (SS/DD 8spt) 180 (SS/DD 9spt) 320 (DS/DD 8spt) 360 (DS/DD 9spt) 640 (DS/QD 8spt) * 720 (DS/QD 9spt) * 1.2 (DS/HD 15spt) 3.5" : 720 (DS/DD 9spt) 1.4 (DS/HD 18spt) 1.6 (Sun workstations) 2.8 (?) * Not IBM standard, but I can read them on my IBM clone, and some Z100's use this format. DJ dj@ctron.com