Magnetostrictive delay-line stores operating at 1 Mc/s using transistor circuits

The paper describes two magnetostrictive delay-line stores which have been developed for use in data processing. The use of transistors has enabled the stores to be constructed in the form of compact plug-in units using printed wiring. One delay line has a delay time of 100 microsec and the other has a delay of 1 millisec. Both use a repetition rate of 1 Mc/s. They therefore store 100 and 1000 binary digits, respectively. The lines use Permendur wire to transmit a longitudinal stress wave. The 1 millisec line has a temperature-compensating device which adjusts the distance between the transducer coils in order to keep the delay time-constant to within ±0.1 microsec over a temperature range of 20°C. The recirculation path of the store is provided by a transistor circuit. The small output signal from the receiving coil of the line is amplified by multi-stage negative-feedback amplifier. Output pulses from the amplifier are shaped by a transistor clipping stage and then lengthened by a novel circuit utilizing the hole-storage effect. The output of the pulse lengthener is gated by clock pulses. This arrangement permits the delay time of the line to vary by 0.6 microsec without affecting the timing of the gated pulses. These pulses are lengthened by a further hole-storage circuit and they supply an output to external circuits via an emitter-follower. The output pulses are of 8 volts amplitude and have rise and fall times of 60 millimicrosec. The output pulses are also fed via `write¿ and `erase¿ gates to the transistor amplifier which drives the sending coil of the line. A companion paper describes circuits for performing logical operations in association with these delay-line stores.