Ferrite films - New logic and storage devices

Magnetic devices for storage and switching applications in digital computers have been fabricated in the form of open flux path elements. The geometry employed is that of a planar film with thicknesses in the range of 5 to 50 μ and other dimensions in the fractional inch range. These elements have the advantages of a ferrite composition and of open flux paths without many of the disadvantages present in similar metallic devices. For use in storage systems, these devices possess excellent squareness characteristics and have coincident selection times comparable with ferrite-toroidal devices. Properties of these devices are given in terms of switching curves, low-frequency hysteresis loops, and one to zero-signal ratios. Other aspects that are discussed include disturb sensitivity of storage elements, heating effects due to high pulse repetition frequency, and mechanical properties. For each of these, comparison is made with other types of magnetic elements such as toroids and metallic films. Applications are discussed in terms of drive requirements, packing densities, and switching times. © 1960 The American Institute of Physics.