In the past few months numerous articles have been published that describe optical video disc systems. (Refs.1-12). In reading through these articles it soon becomes evident that a principle of convergent technical evolution has been at work: the majority of systems under development are remarkably alike in their basic aspects. This convergent evolution is no accident, of course; the criteria for survival have been common to almost all systems. They are cost, simplicity and durability so as to gain acceptance in the consumer market. In less insipid terms: the evolutionary goal that has to be reached is to mass produce an optical read only memory with a capacity of 11 about 10 bits for under $500. The 1011 bits approximately represent the information content of a half-hour T.V. program and the $500 the average cost of a color T. V. set.