Double-layer word straps as a diagnostic technique for use in plated wire studies

A test technique for plated wire memories, which uses two layers of word straps in the read-write operations, is described. Thus a rather wide bit may be established using two 10-mil word straps spaced 5 mils apart. This can then be read using the smaller 5-mil interrogate straps with a 5-mil spacing giving the magnetization distribution at 10-mil increments along the plated wire. Theoretical relationships are developed between the voltages sensed on the digit line upon applying word currents through either of the word straps. Such a configuration is used to estimate the width of material switched by each strap while in a memory mode of operation. Families of curves are given showing how different digit currents, write-word currents, read-word currents, and a number of disturb repeats affect the domain magnetization and readout voltage.