No-cd patches are practically self-explanatory. The patch allows you to play a game without the CD in the drive. Reasons for using no-cd patches vary, but most want to use the patch in order to avoid constantly switching or searching for CDs. They are also used with warez copies of games, making some people wary of sharing and downloading the patches. Game publishers and developers do not support the use of No-CD patches. You game may not work correctly with one.
How No-CD Patches Work
When games are launched they usually look to make sure the CD is in the drive. Usually files aren't being accessed to play the game, but instead to make sure you have a copy of it. No-CD patches take care of this problem.
Gamers will edit the exe file of the game, and take out the command lines to verify the CD is in the CD-drive. When you download a no-cd patch, you'll probably download a zip file with an exe file and text instructions.
similar to No CD Patch:
Game Jackal
virtual CD software
No-CD patches Download:
http://www.g-play.ru/en/download/default.asp?type=nocd
hope it helps.