Newsgroups: comp.sys.ibm.pc
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!hellgate.utah.edu!hellgate!jacobs
From: jacobs@cs.utah.edu (Steven R. Jacobs)
Subject: Re: Formatting 1.2 Meg disks to 360K question
Message-ID: <JACOBS.90Jan9093359@cmos.cs.utah.edu>
In-reply-to: jacobs@chocolate.it.udel.edu's message of 9 Jan 90 00:12:47 GMT
Organization: University of Utah CS Dept
References: <3226@ucrmath.UCR.EDU> <7715@nigel.udel.EDU>
Date: 9 Jan 90 09:33:59

In article <7715@nigel.udel.EDU> jacobs@chocolate.it.udel.edu (michael jacobs) writes:
>In article <3226@ucrmath.UCR.EDU> lulu@ucrmath.UUCP (david lu) writes:
>=>I just tried to format some 1.2 Meg, high density disks in my
>=>360K drive (as 360K), and I got the following error message:
>=>
>=>	Invalid media or Track 0 bad - disk unusable
>=>
>=>Now, I know that I can't format 360K disks to 1.2 Meg in a
>=>1.2 Meg drive, but why can't I format 1.2 Meg disks to 360K
>=>in a 360K drive?  I thought that "blank" disks are just that
>=>-- blank.  They can be reformatted as long as the density is
>=>"thick" enought, right?
>
>Having just had this problem, I asked around and it seems that High Density
>disks and Double Density disks (used for 360k) do have physical differences.
>On the High Density disks, there are only certain places for the sectors
>while the DD's are more flexible since there's less stuff to squeze 
>together.

The person that told you this was either joking or making it up to
disguise their ignorance.  Physically, the two types of disks are
similar, with oxide covering the entire surface of the disk.  The
difference is in the oxide itself.  On the high density disks, the
oxide is a different material which requires a stronger magnetic
field to record information.  The heads in many 360K drives are
not designed to produce a strong enough magnetic field to record
data on the high density floppies.
--
Steve Jacobs  ({bellcore,hplabs,uunet}!utah-cs!jacobs, jacobs@cs.utah.edu)
