Xerox Corporation

Maxtor Corporation

Dennis C Stark

Peter D Doninelli

Marc J Lalouette

Kenneth A Weza

William D Huber

Rod J Swanson

James V Schimandle

Nicholas Bucska

Gerald J Joyce

A searching and block access method on a digitally recorded continuous web media. The method enables a digitally recorded tape to be randomly positioned to access a specific requested data block. This method does not rely on scanning the information recorded on the tape to locate a requested data block. The tape is shuttled at high speeds to randomly requested locations. Tape positioning and control is accomplished by profiling the motion required to position the tape at the requested block relative to any current tape position. A tape directory of contents and tape position is recorded on the tape and cached within the drive controller. The cached version of the tape directory is used for random accesses. The random access ability enables the tape implementation to perform disk storage emulation.

High speed searching of digital cassette

A tape transport system has a cassette housing with two stationary generally cylindrical guide members. The bottom wall has two openings extending therethrough, each of which receive one end of a respective one of the guide members. Each guide member is bonded to the bottom wall by an epoxy resin which forms the sole connection of each of the guide members to the cassette housing. Each of the guide members has an outer exposed substantially precise registration surface at the one end which is received in the bottom wall opening. A cassette tape drive has a pair of spaced apart substantially precise registration and support surfaces which is of a dimension to engage solely the precise registration surface of a respective one of the guide members. The registration surfaces of the guide members and the cassette tape drive are all aligned in the same plane and form a reference plane.

Tape drive and cassette with precise registration

In a tape drive system, a cassette comprises a pair of spaced apart flangeless hubs and an access opening between the hubs. Each hub is provided with a cap of magnetically attractive material. Each hub receives a rotatable spindle which has a magnetic portion at its upper end. There are abutting surfaces on each hub and spindle which act as registration surfaces to provide a contiguous but non engaging relationship between the spindle magnetic portion and the hub cap of magnetically attractive material. The magnetic attraction between the magnetic portion of each spindle and its respective hub is the sole force urging each hub into engagement with its respective spindle. The abutting registration surfaces are located on each spindle relative to the bottom wall of the cassette so as to suspend its respective hub between the housing top and bottom walls. On each side of the access opening, there is mounted a cylindrical guide member which has a stationary flange at each end and a stationary central grooved portion between the flanges. The grooved surface comprises concave grooves providing a surface roughness average between 20 and 40 microinches. Each of said hubs has a tape engagement portion which has a tape center line axially located at the center thereof and each of the guide members has a tape center line axially located thereon at the center of said grooved central portion. When connected to a tape drive, the tape center line of each of the guide members and the hubs are substantially aligned with each other in the same plane. The tape extends in a tape transport path from one hub directly to and engaging the grooved central portion of one guide member and across the access opening directly to and engaging the grooved central portion of the other guide member and directly to the other hub. The guide members are the sole members in the cassette engaged by the tape in the tape transport path between said hubs.

High speed tape transport system

A media flaw detection apparatus having a sensitivity which is independent of the location of the flaw relative to the written test signal. The apparatus is equally sensitive to missing or extra bit defects. According to the invention, in-phase and quadrature-phase signals are heterodyned against the analog playback input signal. The resulting signals are squared and summed to produce a signal analogous to the effect of the flaw.

Growing community of inventors

Los Gatos, CA, United States of America

Dennis C Stark