Development of an e-core read-only memory

Electronic memories in data processing equipment can be divided into two categories. In the first category are easily alterable memories such as ferrite core matrices, ultrasonic delay lines and thin films. These are used for temporary storage of information, for example, the program of instructions for a particular calculation, initial data and intermediate results. In the second category are fixed or "read-only" memories used to store information that is seldom, if ever, changed. Writing the information into these memories is part of the manufacturing process, and in order to change it one has either to replace a part of the memory or to alter its construction in some way.