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From: dpa@snow.UUCP (David Angier)
Newsgroups: net.micro.cbm
Subject: Re: Copy protected disks
Message-ID: <403@snow.UUCP>
Date: Thu, 21-Feb-85 13:42:50 EST
Article-I.D.: snow.403
Posted: Thu Feb 21 13:42:50 1985
Date-Received: Wed, 27-Feb-85 04:01:37 EST
References: <414@bonnie.UUCP>
Organization: Computer Science Department, Warwick University, UK
Lines: 46

> When I boot a protected disk into internal RAM, what's to prevent me
> from copying the program to another disk?  Someone told me that my
> drive heads will get messed up.  Is this true?  Can we discuss how
> one can copy protect their own disk?

About the heads, rubbish.

The usual method of disk protection is to have a boot up program
("loader") that brings in the bulk of the code and does many
nasty things, such as :-

	1) Checking for certain errors on the disk, these are put
	   on the disk during production and are very hard to create
	   otherwise. If the error is not on the disk the program
	   will not work.

	2) Setting up lots of horrible vectors so that there is no way
	   of reseting the machine while loading of after it is loaded.
	   (without turning off that is :-) ).
	   This stops you putting on another disk since there is no
	   way of getting to a save routine.

	3) Writing the loader with a lot of illegal opcodes, these
	   are not documented but do the same things on all 6510's.
	   These make it hard to crack the loader, so that the above
	   is no longer done.

	4) Using bugs in the 6510 to confuse people cracking the loader.

	5) Using tracks 36-40 of the disk drive!!

	6) Auto-running loader that means nothing if loaded in the
	   wrong place.

	7) Encoding the main program chunk so that it means nothing
	   without the loader.

The list goes on and on, to put in your own protection I suggest getting
'Disk Di-Sector' that allows error creation, this will stop all but
the must rabid pirates.

There is some protection that I don't understand, I could back up every
bit on a disk to another disk, find no errors and still not have it
run!

		Dave.