A high-speed card changeable permanent magnet memory--The inverted twistor

A high-speed card changeable permanent magnet twistor memory is described. High switching speeds at low drive current levels are obtained by inverting the twistor (using the twistor wire as the word line rather than the sense line as in previous designs). A 512-word, 24-bit memory having a cycle time capability of 250 ns has been constructed and evaluated. Bipolar drive currents of 600 mA produced switching times of 60 to 70 ns and signal levels of 12 to 16 mV. The characteristics of a 4096-word, 90-bit memory are predicted. Drive currents of 400 mA would produce outputs of 10 mV and a cycle time of less than 400 us.