Magnetic memory cells meet the essential logical and economic requirements1,2 of a memory cell and presently play a dominant role in electronically and mechanically accessed computer memories.3,4 Electronically addressed magnetic memories typically are arranged in 3D, 2D, or 2½D organizations.5–9 Progress in electronically addressed magnetic memories has resulted from a number of basic discoveries and developments in the threshold and switching properties of ferrite cores,10–12 planar thin films,13–15 and plated wires.16 As recently summarized,17,18 mechanically accessed memories such as tapes, drums, disks and data cells have had continual improvements in magnetic materials and in cell density. Present magnetic cells typically do not approach the limits set by thermal noise,19,9 and, as a consequence, a substantial increase in density is possible. The number of magnetic memory cells produced each year is increasing by more than 30% per year3 and continued growth can be anticipated.