Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!apple!vsi1!octopus!pete
From: pete@Octopus.COM (Pete Holzmann)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Low Density Disks in High Density Drives
Summary: It usually works, just not always
Keywords: HD Disk 1.2M 360K
Message-ID: <1989Aug23.152504.2710@Octopus.COM>
Date: 23 Aug 89 15:25:04 GMT
References: <1293@cbnewsd.ATT.COM> <1836@garcon.cso.uiuc.edu>
Reply-To: pete@octopus.UUCP (Pete Holzmann)
Organization: Octopus Enterprises, Cupertino CA
Lines: 37

In article <1836@garcon.cso.uiuc.edu> kubla@uiuc.edu (Kubla Khan) writes:
>In article <1293@cbnewsd.ATT.COM> bryan@cbnewsd.ATT.COM (bryan.k.delaney) writes:
>>1.2M disks require a different write current
>>than the 360/720K disks so you should not use them at 360/720K
>>either.  
>
>This raises yet another question: I have a 1.2M 5-1/4" drive in my AT clone.
>It is able to read/write low density 360K diskettes (using the 360K format)
>with no problems, and I swap 360K diskettes with my XT clone all the time
>with no problems. How does the 1.2M drive know to change its write current
>in order to successfully write a 360K floppy? Or, if it does not change its
>write current, the how do you explain the ability of thousands to read/write
>low density floppies in their high density drives?

You happen to be lucky. It will work for most of the people, most of the
time. It will not work for everyone, all of the time. Failures seem to
depend on particular diskette drive samples. In other words, your AT and
XT happen to be a good match. But if I were you, I wouldn't try sending one
of your 360K-written-on-1.2 diskettes in an expensive-important mailing to
somebody across the country-- they might not be able to read it! If it is
easy to re-do the process, then by all means, go ahead and write the 360K
in the 1.2 drive.

Perhaps the most important situation in which most of us need to be careful:
If installing software that comes on 360K diskettes, into a 1.2 drive, I get
VERY nervous if the diskettes are not write protected. I either write protect
them first, or copy the originals and run the install from the backup (unless
I am sure that the install process doesn't involve writing to the diskettes.)
I've seen too many examples of original-floppies becoming unreadable after
having been 'touched' by the install program.

Pete
-- 
Peter Holzmann, Octopus Enterprises   |(if you're a techie Christian & are
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