Table of Content

Atari FD Copy Protection Mechanisms

I have created a document that describes the copy protection mechanisms used on Atari mainly from a "hardware point of view" (e.g. detail analysis of the flux transitions sampled from FD) and not from a "software point of view" (how a program tests these protections). If you are interested at the software side of the protections you can go to pages like Atari ST Protections from Markus Fritze or Les Protections sur Atari ST/AMIGA (in French) de DlFrSilver.

It is highly recommended that you first read my document Atari Copy Protection Based on Key Disk that provides detailed information about most of the floppy disk protection mechanisms used on the Atari platform.

Analysis of protections at the flux transition level has been done using my new Aufit Program as well as my older Analyzer programs. The flux transitions samples are created using the Discovery Cartridge (on Atari) or the Kryoflux and Supercard Pro devices on PC.

To look at actual analysis of games please go to my Atari Game Protection Analysis page

For follow-up and questions please use the following thread on Atari-Forum.

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Various Protection methods used on the Atari Platform

Many commercial Atari programs/games use some sort of protection mechanism to protect the publishing companies from unauthorized copy of the originals. As for other platforms the protection mechanism has evolved over time from very simple to very sophisticated. The protection mechanisms used on the Atari computers fall into three main categories:
  1. User input based protections
    This first mechanism is requesting the user to type information at the start of (and/or even many times during) the program/game. This information was provided in "documents" that were difficult to reproduce in the 90s (remember that at that time scanners, color copy, etc. where not easily available). For example the documentation could contain colored text that could only be read with special filtering glasses (red and green) or text appearing behind rotating wheels... This kind of protection is relatively cheap to produce (part of the normal documentation) and usually allow to install the program on a hard disk.
  2. Hardware / Dongle Protections
    This second mechanism requires to use an hardware key (also called a dongle) that plugs into an Atari port: usually the cartridge port but sometimes the joystick, or parallel ports. This kind of protection is relatively expensive. It was therefore not used very much in games but was largely used by "professional" programs like musical programs from Steinberg (using dongles plugged on on the cartridge port). Normally programs protected with dongles can be installed on hard disks.
  3. Key disk Protections
    This third mechanism uses a "copy protected disk" or "key disk". In this protection the commercial software manufacturers uses specially formated disk that can not be reproduced by a standard Atari system as a mean to protect their programs. By using special commands the software can verify that an original disk is used and not a copy. This verification is usually done at load time, and the program would refuse to run if the "protection information" was not correctly detected. The copy protection mechanisms on Atari started with simple tricks that could be reproduced by specialized copy software to end up with very sophisticated mechanism that requires special hardware (e.g. Blitz cable, Discovery Cartridge, KryoFlux ...). Note that most key disk protected programs cannot be installed on a hard disk.
    For more information on this type of protection read my document Atari Copy Protection Based on Key Disk.

Note on usage of disk images for running protected programs / games with emulators:

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Program Protection Patents

In the area of protection of computer disc against unauthorized copying many patents exists. Some of them are presented below as they are of interest to understand Atari protections:

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Atari Protection References


As many of the documents referenced here are difficult to find, you will find a local copy of these documents.

Forums Threads

Web Links

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