Abstract: The hammer of a serial impact printer comprises a solenoid including a stationary magnetic structure with an opening extending therethrough and a movable magnetic structure adapted to move through the opening. The movable magnetic structure is accelerated by the flux path from the stationary magnetic structure and through the movable magnetic structure as the gap between the movable and stationary magnetic structures closes such that the movable magnetic structure is in substantially unobstructed free flight before the impact area coupled to the movable magnetic structure strikes the character element. The character element in turn strikes a print receiving medium supported by a platen, typically through an ink-bearing ribbon.

Abstract: A variable reluctance motor of the stepper type is operated as a brushless constant speed DC motor by sensing the position of the rotor during rotation and generating a tachometric signal representing the speed of the rotor in response to the sensed position of the rotor. The tachometric signal is compared with a reference signal to generate a supply voltage to the windings of the stepper motor which will maintain the speed of the rotor substantially constant. The windings of the stepper motor are sequentially energized by the supply voltage in response to sensed position of the rotor. During start-up and prior to the time the motor reaches the predetermined speed, a start-up signal is utilized in addition to the sensed rotary position to sequentially energize the windings with the supplied voltage. The motor is utilized to drive a floppy magnetic data storage disc.

Abstract: A data separator circuit for use in decoding single density encoded data retrieved from a floppy disc, the circuit comprising a phased lock loop edge aligning circuit in combination with logic circuitry for providing a first output of separated data and a second output of the separated clock signals. The separator circuit generates an approximately periodic data window which is held in phased alignment with respect to the approximately periodic clock signal, the data window being utilized to gate out, or separate out only the single density encoded data.