First-and Second-Order Ferrite Memory Core Characteristics and Their Relationship to System Performance

The characteristics of ferrite memory cores are discussed and it is shown how these characteristics relate to the performance of memories with different organizations. First to be discussed are the different memory organizations (3D, 2¿D, and 2D) in which ferrite cores are used. The sense-digit plane configurations for typical systems are discussed and illustrated. Also discussed and illustrated are the primary and secondary response characteristics and it is shown how these characteristics affect the sense output voltage. Test procedures for determining these characteristics, without the necessity for building a complete memory plane, are given. The general considerations are discussed for selecting a core for an application using these test results; this is illustrated with a tabulation of results derived from the testing of a series of 30-mil memory cores. The paper concludes with a brief discussion of core stress sensitivity and temperature characteristics.