DiscSys was a commonly used Disk Protection format in the 80s for the Amstrad CPC. For a protection system it was very basic, relying on modifying track and sector information to non standard formats to prevent copying with the supplied tools. Though it was very trivial to bypass the protection system and copy the disk anyway. Whilst reminiscing about the past, I discovered a small flaw with implementation in the game XOR, here’s what I found…