Abstract: A fixed disk memory subsystem connects to digital signal buses and a power supply of a host computer and includes a printed circuit board forming a subsystem mounting substrate for mounting and connecting a head and disk assembly and drive electronics. The head and disk assembly includes a radially positionable head transducer for flying in close proximity to a data storage surface of at least one rotating data storage disk, an actuator for positioning the data transducer at concentric data tracks defined on the surface, and a DC brushless spindle motor for rotating the data storage disk.

Abstract: In a rotating disk drive for storing and retrieving data used by a host system computer, a narrow gap is provided within a data sector format for each concentric data track of the drive. This gap may be normally located at the end of the track, in a speed tolerance buffer region following the last sector. In the event a media defect is detected which otherwise falls within a NAR area for a particular sector, this gap may be shifted to the beginning of the data track, thereby shifting all of the sectors and their NAR areas backward by the width of the gap. The media defect otherwise falling into the NAR area of a particular sector then falls harmlessly into a data field of a preceding sector, and this preceding sector may then be read and mapped out of service by insertion of a spare sector within the physical track without any loss of user data storage capability.

Abstract: A control system for a micro-Winchester or smaller disk file includes head position control circuitry including at least one servo loop for controlling an electromechanical head positioner relative to a rotating data storage disk, a data controller for controlling reading and writing of data blocks from and to a storage surface of the disk, an interface circuit for connecting the disk file directly to data, address and control buses of a host computer, and a single microprocessor programmed to supervise operations of the head position control circuitry, data controller and interface circuit.

Abstract: A modular unitary disk file subsystem is used directly with a host computer. The subsystem includes a common unitary mounting substrate for power and signal connections to the host and for supplying control and data signals back via data, address and control buses to the host computer through a direct plug-in connection without any cabling between the subsystem and the host. The substrate carries and interconnects a unitary disk store head and disk assembly, a disk store control, a disk file controller, and a data and control interface with the computer. The modular unitary plugin form factor, a single supervisory microcomputer controller and a memory containing basic input/output driver routines directly executable by the host computer allow the subsystem to be transported easily between host computers.

Abstract: An improved control system for a disk file includes head position control circuitry including at least one servo loop for controlling an electromechanical head positioner relative to a rotating data storage disk, a data controller for controlling reading and writing of data blocks from and to a storage surface of the disk, an interface circuit for connecting the disk file directly to data, address and control buses of a host computer, and a single microprocessor programmed to supervise operations of the head position control circuitry, data controller and interface circuit.

Abstract: An optical encoder having controllable lead lag phase trim sensitivity includes a light source, and a pair of coplanar photodetectors adjacent each another for generating phased electrical signals in response to light energy generated by the light source. A scale between the light source and photodetectors has alternating opaque and translucent regions extending substantially perpendicular to a locus of relative movement. A reticle has alternating opaque and translucent regions parallel to the regions of the scale so that relative movement of the scale and reticle alternately blocks and transmits light to the pair of photodetectors which put out phased electrical signals indicative of relative position and direction of movement of the scale and reticle. A substantially lineal light blocking zone formed on the reticle is arranged at a predetermined acute rotational angle relative to the locus of relative movement between the scale and reticle.

Abstract: A disk drive storage device employs two control subsystems, one for transducer position digital control and the other to control and precisely regulate spindle motor angular velocity in accordance with a crystal reference and a speed correction made at least once each revolution. A single servo sector on a data surface provides prerecorded track centering information. Overall electromechanical operations during track following activities are synchronized by the crystal controlled disk spindle motor subsystem which locates the position in time and space of the servo sector and which also interrupts program execution of the transducer position digital control subsystem and causes it to execute a subroutine for track centerline position correction. Direct digital commutation of the brushless DC spindle motor by a programmed digital microprocessor is an aspect of the present invention.

Abstract: A self contained fixed rotating disk expansion board subsystem may be installed and connected at an expansion slot location of a host computer. The subsystem includes an enclosed head/disk assembly, and circuit elements mounted on a printed circuit board which includes a connector for connecting to the control, data and address buses of the host computer at the expansion slot location. The head/disk assembly is mounted to a mounting substrate which may be the circuit board or which may be a frame to which the circuit board is also attached. Input/output routines are preferably provided to enable the host computer to make use of the subsystem without software driver modifications in the host operating system.

Abstract: In an optical encoder with a single light source, an array of a plurality of spaced photodetectors formed on a common substrate, a reticle disposed in fixed position relative to said photodetector array, and a scale of alternating translucent and opaque regions relatively moveable between said light source and said reticle so as to cause said array to provide a plurality of phase related analog signals whose amplitudes vary with the position of said scale, an improved digital automatic gain control is disclosed. A digital switch selects one of said analog signals and an analog to digital converter converts and puts out the selected signal as a digital value. A programmed microprocessor reads each such digitized signal, determines the signal value corresponding to maximum light transmission, compares said value with a nominal reference value, and computes a correction value therefrom.