Abstract: A magnetic transducing assembly including an elongate magnetic flux carrying core member, a substrate with a flat multi-turn spiral on a surface thereof and slit opening at the center of the spiral. The core is so engaged in the slit that the plane of the spiral is aligned with the elongate direction of the core and so that the spiral forms a coil about the core member.

Abstract: In a magnetic disc data storage device using exchangeable magnetic discs for recording data signals, a track containing reference signals is provided and a read-write head is moved to the reference track and as the disc rotates, the position of the head relative to the axis of rotation of the head is sampled. Any errors in the position of the reference signals due to eccentricity of the track are stored and are used during subsequent accesses of data tracks on the disc to modify the head position so as to ensure that the head follows a track having a predetermined spatial relationship with the reference track.

Abstract: An interactive display having an array of independently labelled display elements such as LEDs. The output of a recirculating shift register is supplied as long or short pulses which are scanned across the array. Each element in response emits either long flashes and appears lit or short flashes and appears unlit. A light-pen, when pointed at an element, detects the flash from that element, and causes a bit of the opposite sense to be introduced into the shift register in place of the recirculated bit. The display state of each element can thus be changed, both from lit to unlit or vice versa. The contents of the shift register can also be transferred to exterior equipment or supplied by it, allowing the display to act as an input/out device.