Re: Did Commodore cheat with the quad density floppies?

From: afachat_at_gmx.de
Date: Fri, 04 Jan 2019 23:08:23 +0100
Message-ID: <4374150.zDoJRMQzFb@euler>
On Freitag, 4. Januar 2019 22:08:33 CET Francesco Messineo wrote:

> 8 inch drives have another interesting characteristic: they need to
> reduce the write current when writing on the upper half (tracks 43-77) of
> the media. 8-inch floppies are huge, linear velocity of the actual media
> under the R/W head varies a lot between track 0 and track 77, so (I'm
> assuming) using the same current when the linear velocity of the media gets
> too slow (on inner tracks 43-77) produced probably too
> large flux areas and needed to be reduced in order to maintain small
> enough magnetic areas. If someone has an official explanation why the
> 8-inch drives needed to reduce the write current, I'd appreciate to
> know it.

Maybe you can find something in these links:
https://archive.org/details/
bitsavers_motorolaapndWritingInFloppyDiskSystems_1029819/page/n1

http://www.lintech.org/comp-per/07MAGREC.pdf

https://www.birmingham.ac.uk/Documents/college-eps/metallurgy/research/
Magnetic-Materials-Background/Magnetic-Materials-Background-11-Magnetic-
Recording-Media.pdf

André
Received on 2019-01-05 00:00:07

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