The hardware of a wearable computer is in some respects quite traditional, and in some respects wildly different from conventional computer hardware. In short, a wearable computer requires a small computer, some sort of output device such as a head-mounted display or audio system, and various inputs, such as a small keyboard or keyer and a pointer of some kind. Other types of input such as camera (video) input and voice input are possible, but less researched.