David B Graves

US Patent:

62595784, Jul 10, 2001

Filed:

Jun 11, 1996

Appl. No.:

8/664279

Inventors:

Dale Allen Christiansen - Tucson AZ
Kenneth Dean Cummings - Tucson AZ
David Conrad Graves - Tucson AZ
James Lee Lentz - Tucson AZ
Donald Ernest Lockett - Tucson AZ
Guillermo Santamaria Robles - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 1568

US Classification:

360 92

Abstract:

An automatic cartridge feeder includes a magazine slot that receives a cartridge magazine and includes a priority slot that directly receives single cartridges. The automatic cartridge feeder can receive a cartridge through the priority slot regardless of the condition of the cartridge magazine. In an automatic mode, cartridges are taken sequentially from the magazine and are processed. Any cartridge placed in the priority slot by an operator will be processed immediately after any in-progress cartridge processing. In an accumulate mode, cartridges are received through the priority slot for processing and are returned in sequence to an empty cartridge magazine.

US Patent:

53942809, Feb 28, 1995

Filed:

Jun 14, 1993

Appl. No.:

8/075622

Inventors:

Alex Chliwnyj - Tucson AZ
David C. Graves - Tucson AZ
Scott M. Fry - Tucson AZ
Habib M. Torab - Tucson AZ
Will A. Wright - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584
G11B 509
G11B 5596

US Classification:

360 7712

Abstract:

A magnetic tape drive simultaneously senses on a magnetic tape three evenly spaced-apart servo track areas for servoing a multi-track magnetic head to follow a concurrent set of data tracks on the magnetic tape. The data tracks are arranged into a plurality of track groups. Each track group has a first and second subgroup of data tracks. The first subgroup of tracks are scanned in a first relative motion of the magnetic tape and magnetic head as a forward direction (tape is being spooled from a supply tape reel). The second subgroup of tracks are scanned in a second relative motion of the magnetic tape and magnetic head that is opposite in direction to the first relative direction and is a forward direction of scanning. While writing data in any one of the plural track groups, a servo dropout affecting most of the servo track areas is detected and indicated as a servo error. Writing is aborted.

US Patent:

52650820, Nov 23, 1993

Filed:

Oct 3, 1991

Appl. No.:

7/770378

Inventors:

John J. Gniewek - Tucson AZ
David C. Graves - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 509

US Classification:

369 53

Abstract:

A system uses prevent and detect mechanisms to enable rewritable data storage media to be operated as a written-once-only media. A physical indication of the media casing serves as an indicator of the write-once-only status of the media. A watermark is magnetically recorded on the media at the factory with a portion of the mark detectable by the system and a portion only detectable by returning to an inspection station for verification. This protects against a complete erasure of all data from the media. A segment write status indication serves to indicate the write-once-only status of each segment of the written data. A portion of the written region, such as the preamble or control field of each segment, contains a status mark written randomly within the area as a status indication that the data was written once or multiple times within that segment. Three status mark areas in each segment write status region provides the minimum space overhead for achieving the desired degree of protection against overwrite or a pattern repetition.

US Patent:

62798456, Aug 28, 2001

Filed:

Sep 12, 2000

Appl. No.:

9/660109

Inventors:

Wayne R. Hemzacek - Westminster CO
David T. Hoge - Westminster CO
Joseph P. Falace - Louisville CO
David C. Graves - Fort Collins CO
Clark Janssen - Loveland CO
Michael W. Johnson - Cottage Grove MN
Steven A. Bendson - Edina MN

Assignee:

Storage Technology Corporation - Louisville CO

International Classification:

G11B 2304

US Classification:

242340

Abstract:

A coupling for driving a magnetic tape reel uses the interface between a flat surface on the coupling and datum pads on the reel to locate the reel. The coupling includes a drive ring with ring teeth located around a drive shaft. The ring teeth engage mating teeth on the tape reel. The coupling also includes a datum ring having an annular surface located about the drive shaft. The annular surface contacts datum pads on the tape reel to axially position the tape reel relative to the drive shaft.

US Patent:

45801762, Apr 1, 1986

Filed:

Nov 21, 1983

Appl. No.:

6/553938

Inventors:

David C. Graves - Tucson AZ
Richard C. Schneider - Tucson AZ
Volker Zimmermann - Sindelfingen, DE

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 502
G11B 509

US Classification:

360 45

Abstract:

An adaptive equalization circuit for magnetic recording channels which derives an error signal to change the equalizer compensation value from the timing of random signal data and provides continuous feedback compensation.

US Patent:

54326524, Jul 11, 1995

Filed:

Jun 14, 1993

Appl. No.:

8/075625

Inventors:

Wayne T. Comeaux - Tucson AZ
David C. Graves - Tucson AZ
Douglas W. Johnson - Rochester MN

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5584

US Classification:

360 7712

Abstract:

A magnetic tape has three evenly spaced-apart longitudinally-extending servo track areas. Four equal-sized longitudinally-extending data track areas are disposed between said servo track areas and between longitudinal edges of the tape and one of said longitudinally-extending data track areas. For track following, all servo track areas are simultaneously sensed for producing one head positioning signal. Data tracks are arranged into four groups of tracks, one-half of the data tracks in each group are concurrently accessed. The data tracks on the tape are arranged in clusters. Each cluster has one track from each of the groups of tracks. Two laterally-adjacent track clusters constitute four data track wraps for serpentine scanning of data tracks. The concurrent track accessing respectively occurs in first and second halves of a data track wrap (there is a number of wraps equal to one half the number of track clusters). Each servo area indicates two lateral positions of the tape to the head.

US Patent:

56594402, Aug 19, 1997

Filed:

Mar 14, 1995

Appl. No.:

8/404401

Inventors:

Donald Charles Acosta - San Jose CA
David Conrad Graves - Tucson AZ
Paul Yu-Fei Hu - Tucson AZ
James Alfred Jackmond - Tuscon AZ
Loyal Keith Whitted - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 15675

US Classification:

360 92

Abstract:

A cartridge magazine with interfaces to automatic cartridge feeder devices. On one side, the magazine has an open interface that provides unencumbered access by a robotic picker that accesses cartridges for a library. The magazine is accessible on another side by a transport mechanism of an automatic cartridge feeder (ACF). The transport carries a cartridge from the magazine to a drive unit where the data stored on the cartridge is read or new data is written. The interface to the ACF includes a handle member for placing the magazine into the feeder. The magazine is mounted by loading it into the feeder and pushing the handle inward allowing a plunger on the ACF to engage a groove on the handle member that locks the magazine into place. Locking the magazine in place activates a sensor, thereby enabling the operation of the feeder. The interface securely engages the ACF so that the magazine cannot be accidentally dislodged from it.