Magnetic drum recording of digital data

MAGNETIC recording has attained an important position in the field of digital data storage because of its simplicity and economy. Information is handled in binary form, requiring a discrimination between only two states. These states correspond to two opposite senses of saturation, and new information is then merely recorded over that previously contained, erasing being unnecessary. This paper is primarily concerned with the development of a useful mathematical description of the process of magnetic recording of binary information. A concept of this process is developed which furnishes an analytical basis for design evaluation. While a large part of the following is applicable to binary storage on a continuous magnetic medium in general, the paper is specifically concerned with a magnetic drum unit using a ring-type magnetic recording head, wherein the type of magnetization is referred to as longitudinal. This is at present the most common form for a magnetic drum memory system.