A display apparatus and method of displaying an image, and a video signal processor and method of converting an input video signal into a displayable format compatible with the display, including an reproducing apparatus reading out data stored on a medium, a playback part converting the data read by the optical disk drive into a video signal compatible with the video signal processor, an interface transmitting and receiving data to and from an external device, e.g., a computer, and a switching part selectively enabling the reproducing apparatus to communicate with either the drive playback part or the external device. With this configuration, embodiments of the present invention provide a display apparatus, computer system, and methods, using a display apparatus to play back a medium, e.g., a DVD having multimedia functionality, without having to boot the computer system.