Copy Protection: Key Disk
One or more of the original game disks included a mechanism to prevent copying via common commands or utilities; each time the game was played, an original disk needed to be in the disk drive in order to run. The mechanisms to achieve this were varied and ranged from using non-standard sector sizes to using a laser to physically damage a given sector. Generally, the disk was formatted in such a manner that could be created by professional disk duplicators but could not be written using commercially available consumer disk drives.
Copy Protection: Key Disk is part of the tagging category Copy Protection.