Date   : Fri, 28 Oct 2005 00:01:03 +0100
From   : "David Hunt" <dm.hunt@...>
Subject: Re: Formatting a disk beyond 80 tracks

> -----Original Message-----
> From: Majordomo List Manager [mailto:majordomo@...] On Behalf Of
> A. J. Davis
> Sent: 27 October 2005 22:18
> To: BBC Micro Mailing List
> Subject: [BBC-Micro] Formatting a disk beyond 80 tracks
> 
> Has anyone ever done any experiments with formatting a disk beyond 80
> tracks?  I first noticed you could get a few more out of a disk about
> ten years ago with a 5.25" drive on a Sinclair Spectrum (with +D
> interface).
> 
> The format command was built in, but you were able to modify the DOS
> (ironically it had to be loaded in on disk first!) to the number of
> drives, whether they were single or double sided and the number of
> tracks. (it was a 10 sectors per track, 40 or 80 tracks per disk
> arrangement).
> 
> While 3.5" disks would usually only format to 81 tracks I found I could
> get upto 85 on the 5.25" disks.
> 
> This gave birth to some pretty good copy protection techniques where a
> hidden piece of code would search for a verification code on the hidden
> track and if it wasn't present would format the disk.
> 
> I was playing around with J.G. Hartson's disk format program -
> http://www.mdfs.net/Software/BBC/FormDFS.txt - and got some interesting
> results testing it on Beebem. I've not had the time to try it on my twin
> drives on the Master yet.

I got 86 tracks on one of two identical TEAC drives, only 85 on the other.
Basil Bloom would copy the whole disc though. I used Disc Doctor to format
the discs. Quite a few drives choked after 82 tracks though.

In a similar vein, I used to have a program that staggered the sectors of a
disc so a track could be read without waiting for a revolution of the disc
to pass first. You could hear the drive head clicking across at almost twice
the speed. This made loading programs so much faster. Mind you with the
GoMMC card lightning speed is the order of the day anyway!

Dave ;)