Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ames!killer!bobc
From: bobc@killer.DALLAS.TX.US (Bob Calbridge)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Question about diskette densities
Summary: and also
Message-ID: <8428@killer.DALLAS.TX.US>
Date: 21 Jun 89 23:16:35 GMT
References: <1559@cbnewsh.ATT.COM> <586@megatek.UUCP>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 37

In article <586@megatek.UUCP>, hollen@zeta.megatek.uucp (Dion Hollenbeck) writes:
+ From article <2210@bingvaxu.cc.binghamton.edu>, by vu0112@bingvaxu.cc.binghamton.edu (Cliff Joslyn):
+ > 
+ > I'm beginning to doubt common sense about diskette densities.  Both
+ > single and double sided diskettes can be formatted as if they were
+ > double.  I'm told it's simply a difference in quality control.  On my
+ > new 1.2 meg 5.25" drive I can format DS/DD disks at 1.2 meg?  What am I
+ > risking by not buying HD disks?  etc.
+ 
+ 
+ You didn't ask this, but it may help someone.  DSDD disks can be 
+ formatted for up to 800k.  This is an unusual configuration because
+ it uses 10 sectors per track which the UCSD p-System does reliably,
+ but I never figured out why MS-DOS only used a max of 9 per track.
+ The format using 9 sectors per track is 80 tracks of 8 sectors for
+ a total of 720k.  You merely need to tell DOS via DRIVPARM or by
+ using DRIVER.SYS that you have a 720k 3 1/2" drive and it will not
+ know that you really have a 720k 5 1/4".  BTW, you must have the
+ correct disk drive (like a Shugart 465).  A standard 360k drive will
+ NOT make or read 720k disks and a 720k driver will not make or read
+ 360k disks.  FASTBACK PLUS can be configured to recognize these
+ drives as 720k drives and works perfectly.  In fact, this is the
+ use I have put them to.

Along a similar line I forgetfully forgot the /4 switch with a 360K diskette
in the drive.  The program dutifully formatted the diskette.  However, I
showed a bit more than 720K on the disk and a rather large number of bad 
sectors to make up the remaining 1.2M.  I went ahead and copied a large
number of files onto the diskette and it copied okay.  Reading the disk
presented no problem and copying from it worked fine.  

However, I'm not going trust this to keep my important files on.
-- 
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=             I know it's petty..........                                     =
-                  But I have to justify my salary!                           -
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