TECHNOLOGICAL SUBSTITUTIONS IN THE COMPUTER INDUSTRY

Substitution among computer products is treated as a natural process amenable to a description by a logistic growth function. The Fisher-Pry model generalized by Marchetti and Nakicenovic works well for such technological transitions as Digital's PDP to VAX. Examples are given for product substitutions in the low end of the product range, the microcomputers. The most important factor which influences the rate of substitution is compatibility of software. With high compatibility a substitution goes from 20% to 80% in less than one year. With low compatibility, a new tecnnology may take up to three times as long.