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: Higher data storage capacity is realized in a self contained fixed rotating disk expansion board subsystem preferably for a single electronics circuit board accessory slot of a host computer. This greater capacity, e.g. 42 megabytes of formatted storage on two 95 millimeter disks, is achieved by use of a plural zone arrangement wherein each zone contains data tracks in which user blocks are recorded and read out at a data rate unique for the zone. An improved phase locked loop within the data separator uses a separate voltage controlled oscillator for each zone and a common charge pump for generating control voltages applied to change the resonant frequency of all of the oscillators. An oscillator disable circuit disables every voltage controlled oscillator other than the selected oscillator, so that it is the only oscillator whose frequency is actually varied by the charge pump during readback/data separation and decode operations.

Abstract: Higher data storage capacity is realized in a self contained fixed rotating disk expansion board subsystem preferably for a single electronics circuit board accessory slot of a host computer. This greater capacity, e.g. 42 megabytes of formatted storage on two 95 millimeter disks, is achieved by use of a plural zone arrangement wherein each zone contains data tracks in which user blocks are recorded and read out at a data rate unique for the zone. An improved phase locked loop within the data separator uses a separate voltage controlled oscillator for each zone and a commmon charge pump for generating control voltages applied to change the resonant frequency of all of the oscillators, An oscillator disable circuit disables every voltage controlled oscillator other than the selected oscillator, so that it is the only oscillator whose frequency is actually varied by the charge pump during readback/data separation and decode operations.

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: A compact, sealed head and disk assembly for a rotating non-removable disk data storage subsystem includes a flat and thin rigid generally rectangular box housing having a length not greater than approximately 173 millimeters, a width not greater than approximately 102 millimeters and a height not greater than approximately 24.5 millimeters,; a thin spindle motor mounted within the form factor of the housing; at least one magnetic media data storage disk having a diameter of approximately 95 millimeters in the housing and mounted directly to the spindle for rotation; a limited angular displacement rotary actuator subassembly including a substantially planar limited displacement rotary actuator motor; and, a cover for closing and sealing the housing.

Abstract: A compact, sealed head and disk assembly for a rotating non-removable disk data storage subsystem includes a flat and thin rigid generally rectangular box housing; a thin spindle motor mounted within the form factor of the housing; a magnetic media data storage disk in the housing and mounted directly to the spindle for rotation; a limited angular displacement rotary actuator subassembly including a substantially planar limited displacement rotary actuator motor; and a cover for closing and sealing the housing.

Abstract: A compact polyphase optical encoder subassembly for installation in host equipment is disclosed. The subassembly includes a moveable scale; and, a unitized rotatable housing for aligning a light source, a mask and a photodetector array having at least a pair of photodetector areas symmetrically disposed about an axis of rotation of the housing and responsive to light energy from the light source in further response to relative position of the scale. The housing further includes in its preferred form a bolt having a widened head and a threaded shank for passing through an opening in a base of the host, a threaded nut engageable with the shank opposite to the head for thereby securing the bolt to the base, and a compressible washer for enabling a predetermined range of vertical compression between the head and the base as the nut is tightened on said shaft.

Abstract: An improved optical encoder is disclosed. The encoder includes a moveable scale with alternating equally dimensioned opaque and translucent regions extending generally perpendicular to the locus of scale movement; and a light source, a mask and a rectangular photodetector array having at least a pair of generally symmetrical, rectangular photodetector areas, the longitudinal dimensions of those areas being disposed relative to the regions of the scale at a predetermined acute angle of rotation. The mask defines at least two series of equally spaced apart elongated phase shifted openings aligned to be generally parallel with the regions of the scale, the mask openings being aligned at the same angle of rotation as the major lineal dimensions of the photodetector areas. The mask openings are substantially coextensive with the rectangular photodetector areas. The light source, mask and photodetector array are commonly mounted on a single axis of rotation in a rotatable stationary housing.

Abstract: An aerodynamically powered release latch mechanism for a fixed disk data file is disclosed. An airflow generator disk is commonly journalled with a single data storage disk for generating airflow in an enclosed chamber. A latch is journalled for rotation relative to a base casting and has an axis of rotation spaced a predetermined distance away from the periphery of the data storage disk. The latch includes a vane movably disposed in a space defined between the airflow generator disk and the data storage disk so as to be deflected by airflow generated by rotation thereof. A releasable engagement mechanism engages a rotary actuator assembly in a locking position in the range of relative movements therebetween whenever airflow is insufficient to deflect the vane. A bias spring is operable between the latch and the base casting for maintaining the engagement mechanism in locking position in the absence of airflow.

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.