The process of applying a no-CD patch involved downloading a small software file from the internet, which was then applied to the game. This modified the game's code in memory, allowing it to skip the CD authentication process. The patch did not alter the game's functionality or content; it merely removed the need for the physical media.
Disclaimer: This guide is for educational purposes and for users who own a legal, physical copy of the game. Modifying executable files may be flagged by antivirus software (more on that below). Always scan files before running them. simcity 3000 no cd patch