New HD disks not working in 1541?

From: Pete Turnbull <pete_at_dunnington.u-net.com>
Date: Wed May 30 14:39:19 2001

On May 30, 14:23, Roger Merchberger wrote:

> HD disks AFAIK won't work at all in any DD drive - the TPI (Tracks Per
> Inch) are different. DD disks are 48TPI, HD disks are 96TPI.

I have to say that this is not true.

Plenty of DD disks are rated for 96 or 100 tpi. Furthermore, at the
microscopic level, there is no difference between a DD disk sold for 96 tpi
and one sold as 48 tpi. There might be more gross defects in older
sold-as-48 tpi disk than in 96 tpi ones, I admit, and that could produce an
error when narrow tracks are written. Nevertheless, the magnetic
coercivity of the disk is the same in both cases.

The difference between HD and DD is NOTHING to do with tracks per inch,
it's ENTIRELY to do with the coercivity (which is a measure of the field
strength required to produce the magentic polarisation used to write the
data).



-- 
Pete						Peter Turnbull
						Network Manager
						University of York
Received on Wed May 30 2001 - 14:39:19 BST

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