This pattern can then be read back by an optical sensor inside a CD drive or player.

Suppose a computer has three CD drives and three processes.

Not all CD drives can properly extract such hidden tracks.

There can be compatibility issues with this format and some CD drives.

This system does not require user to keep the disc inside the CD drive while playing games.

Is that a mechanical problem with the CD drive?

Also, not all CD drives can read them.

On other models, you may need to unscrew the bottom of the computer or temporarily lift up the keyboard to get to the CD drive.

This version will use the CD drive for installation, running only from the hard drive.

The machines also support tower cases, making it possible to use internal CD drives.