Path: utzoo!attcan!uunet!ubvax!ardent!rap
From: rap@ardent.UUCP (Rob Peck)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Copy Protection Schemes
Summary: defeats "standard" Amiga used as a copier
Keywords: Copy Protection Schemes, MFM format
Message-ID: <2075@ardent.UUCP>
Date: 25 Jan 89 19:35:13 GMT
References: <1411@anuck.UUCP>
Organization: Dana Computer, Inc., Sunnyvale, CA
Lines: 28

In article <1411@anuck.UUCP>, ksp@anuck.UUCP (p.s.kasten) writes:
> I hope this doesn't start a discussion of the pros and cons of copy
> protection.  All I'm looking for is some info...
> 
> How do these schemes work?  If the AMIGA can read a RAW track and write a
> RAW track, how does the copy become different from the original?  Especially

The one copy protection scheme that I don't believe can be broken for a
standard Amiga to be used as a raw track copier is based on the syncing
ability of the Paula chip (I believe this is the correct one...).  The
disk read circuitry can synchronize to a faster bit rate than, under
actual clock control, it can write.  Thus if the standard number of
sectors on a track is 11, as I recall by writing the disk on a special
machine with a faster bit rate than the Amiga, one could squeeze 12
sectors, formatted normally so to speak, on the same track.  The Amiga
could sync to this higher rate, but using a standard clock, like "Joe Breaker"
has in his machine, it would be possible to READ this data, but not
enough room on the disk to WRITE it out again for the copy in a single
revolution.  Thus unless the program code was hacked as well, this
would make it a lot harder to break and impossible on a standard
machine to copy.  (My exposure to Amy hardware is over 2 years old,
so I might not be correct, but this is something I recall from some
time past).

I don't know about any other schemes, but this one always impressed me
as pretty good.

Rob Peck