Xref: utzoo comp.sys.ibm.pc.misc:10466 comp.sys.ibm.pc.hardware:9924 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!comp.vuw.ac.nz!waikato.ac.nz!canterbury!cctr132 From: cctr132@csc.canterbury.ac.nz (Nick FitzGerald, CSC, Uni. of Canterbury, NZ) Newsgroups: comp.sys.ibm.pc.misc,comp.sys.ibm.pc.hardware Subject: Re: DS HD floppies Message-ID: <1991Jun18.201652.1130@csc.canterbury.ac.nz> Date: 18 Jun 91 08:16:51 GMT References: Organization: University of Canterbury, Christchurch, New Zealand Lines: 59 In article , chris@genly.UUCP (Chris Hind Genly) writes: > I'd like some help understanding the various types of floppies. I have a > really old machine at home, an 8088, with a 5 1/4 inch floppy drive that > works with DS DD disks. I'm running PCDOS 2.10. I tried to format a 5 1/4 > inch DS HD floppy on my machine and I got an error message along the lines of > 'track 0 unwritable.' The two types of floppies appear identical to the eye. > I assumed that I'd be able to format the HD floppy as a DD floppy and just > waste the bandwidth. > > 1) Why can't I format a DS HD diskette as a DS DD disk? Assuming that you do not have a diskette that has a genuinely "bad" spot on track 0 (referred to below as the first track), the following may be useful: I seem to remember (vaguely) that DOS used to be fussy about formatting already formatted diskettes to a _different_ format than they were already formatted to. Eg. A DS DD formatted to 320K would not be re-formatted to 360K, but to 320K. _Most_ (OK, so yours doesn't! _I_ am yet to see one that don't) DD drives accurately read the first track of both DD and HD disks (you can usually do a DIR listing of a HD, but trying to TYPE, COPY or execute the files results in a "Sector not found" error, or less often, a "Bad sector" error. My guess is that the HD diskettes are pre-formatted and the DOS FORMAT prog is reading the media-descriptor byte from the FAT OK (cause it's on that first track). This tells FORMAT the disk format to use, and something is going wrong from there - the error message may itself be erroneously identifying the source of error. (I doubt that DOS 2.10 knew anything about HD 5 1/4's, so may be spitting over the 1.2M media- descriptor value it gets - it make "err on the side of caution", suspecting that it is actually a non-DOS disk and the "unwritable" message would be something of a warning.) Now, I'm not sure if this "problem" with FORMAT being "bloody minded" about this sort of thing is in later versions of DOS or not, so trying on a PC with a more recent DOS may do the trick, or use a third-party FORMAT routine (eg. the one in PC-Tools formats to what you select, regardless of what's already there). > 2) Is there a slot or hole somewhere in the floppy jacket that tells > the drive what capacity disk is inserted? Not with 5 1/4's for DOS-like machines (that I've ever seen - to be on the safe side 8-) ). > 2) What are the various diskette formats available now, and what > are thier capacities? What school did you go to? 1, 2, 2 ?? 8-) But seriously: I think this has already been answered in another post. --------------------------------------------------------------------------- Nick FitzGerald, PC Applications Consultant, CSC, Uni of Canterbury, N.Z. Internet: n.fitzgerald@csc.canterbury.ac.nz Phone: (64)(3) 642-337