stepping machanism of Apple Disk ][ drive (was Re: Heatkit 5

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Fri Apr 9 15:34:50 1999

On Fri, 9 Apr 1999, Max Eskin wrote:
> On Thu, 8 Apr 1999 CLASSICCMP_at_trailing-edge.com wrote:
> >I suspect when you say "MFM" you mean "all the soft-sectored data storage
> >schemes descended from the original IBM 3740 (FM) standard", in which case
> >you're right.
> So, does that mean that those quarter-track schemes used for copy
> protection on the Apple II could also be implemented on a PC or
> Macintosh disk? The reason why I ask is because I've never heard of such a
> practice.

The PC (and TRS-80) process all of the disk I/O through a "Floppy disk
controller" chip. Which doesn't permit the stepping weirdities, but does
permit some other ways to deliberately misrecord the disk for copy
protection systems.
Received on Fri Apr 09 1999 - 15:34:50 BST