Computer memories and the impact of semiconductor technology

The universality of the stored program computer depends on electrically addressable memories. The standard memory today is the core array. Historically preceded by electrostatic tubes it has been followed by a variety of other magnetic memories, such as thin films and the plated wire, by superconductive memories, and more recently by semiconductor memories. All these memories are electronic systems in which storing elements are arranged in a matrix, each at the intersection of two or more conductors, and so endowed that the energization of address-selecting combination of matrix line conductors results in the almost immediate and exclusive access to the desired group of cells. It is not surprising, therefore, that many system aspects are similar despite the diversity of physical phenomena utilized, e.g., the minimization of disturb signals due to unavoidably partially energized cells, organizations by bit or word with two or three "2-1/2" signals per cell and the resulting effects on driving circuitry requirements and speed, etc. The system point of view will be taken in a brief history and state-of-the-art account of all computer memories.