Abstract: A system for controlling the operation of a polyphase DC motor having a rotor and a plurality of phase windings with separate outer terminals and a common center tap terminal supplies electrical energy sequentially to the phase windings to produce rotation of the rotor relative to the phase windings. The voltage between the outer terminal of one of the phase windings and the center tap terminal is sensed during periods when that one phase winding is not energized to control the sequential supplying of electrical energy to the phase windings.

Abstract: A read/write apparatus for magnetic recorders including a decoder for converting input digital control and data signals into a plurality of select signals, a voltage source switchably connected to the read/write heads of the apparatus such that individual select lines are enabled for determining which recording head is actuated for writing on a chosen magnetic medium, what orientation of magnetic flux will be written, and what magnitude of flux will be written. Also, the select lines operate, when the voltage source is disabled, to condition the heads to allow read-out of data recorded on the magnetic media, and to select which head is to perform this read-out. Also included in the recorder is a signal redigitizer to digitize data read from the magnetic media, and erase means for reducing edge and transient effects on the magnetic media.

Abstract: Decoding apparatus for separating clock and data pulses from a double-frequency pulse train, including a retriggerable window one-shot, a bit shift compensation circuit, clock rate tracking means, data bit and clock bit gates, means for keeping track of whether a specific pulse is a data pulse or a clock pulse, and means for actuating the data bit and clock bit gates, based on the status of the system and the state of the window one-shot. The apparatus also provides means for detecting when a clock pulse is missing, including circuitry which simulates the detection of a clock pulse to the rest of the device to keep the system status and timing properly synchronized to the pulse train data.