Forms of wearable computer

This paper introduces the microprocessor, communicating and sensing technologies relevant to wearable computing. It reviews the trends and challenges that form part of the evolution of computer technology, from a computer filling a room to a room full of invisible computers. Not all wearable computing systems require the same level of computing performance or functionality. A Processor Performance and Flexibility of Function (PPaFF) scale is introduced to classify wearable computing systems and is related to the prototypes described in Weiser´s vision of the 21 ^st century computer.