MEMORIES.

A redundancy feature incorporated in large semiconductor memories as a cure for some yield problems is investigated. For each memory type that now incorporates redundancy there is a corresponding version of that chip from another vender who maintains that the feature is unnecessary. There is, however, almost unanimous agreement that redundancy is an absolute must for 256-K RAM. Electrical fuses and laser targets, two programming elements for removing bad memory cells are presented. The use of more than one redundancy programming method at a time, depending upon the type of device, is also discussed.