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From:	"arizvi" <ahmadwaris AT hotmail DOT com>
Newsgroups:	comp.os.msdos.programmer,comp.os.msdos.djgpp
Subject:	Creating a copy protected floppy
Date:	12 Jul 2005 13:22:11 -0700
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Hi everyone,

I am trying to create a copy-protected floppy for distributing my
application. I searched online and decided on bit-counting as perhaps
the best way for me to implement copy protection. A description of bit
counting is given below:

"Two disk drives do not turn at precisely the same speed. Even the same
disk has small variations in its speed. When a disk is formatted, there
is some empty space remaining on each track between the end of the last
sector and the beginning of the first sector. The formatting program
fills this space with meaningless bits. The size of the space (the
number of bits), and therefore the total number of bits on the track,
depends on the rotational speed of the disk drive. If the bits are
counted, and the count is recorded somewhere else in the disk, the
software can find if the disk is original or copied and can bail out."

However, I dont know how to implement this feature. If I use bios calls
to read a sector, I believe that I will read exactly 512 bytes or the
size of a standard sector. This will defeat my attempt to find the
exact # of bits on a track.

Is there some code to get at the number of bits directly from the
floppy drive controller? Or can I somehow use the standard bios calls
to read the number of bits?

Any help will be appreciated. 
Thanks,
Ahmad Rizvi

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