Combined Reading and Writing on a Magnetic Drum

This paper points out that the characteristics of magnetic recording make it possible to combine reading and writing in the same cell as it passes just once under the head. Amplifier requirements for this method of operation are discussed and a suitable design presented. A single head is used for both reading and writing. The process can be repeated in every successive cell at a cell rate of 60 kc. The techniques described, which are applicable to either parallel or serial systems, extend the utility of magnetic drums by allowing data processing as well as data storage.