Charles W Riggle

US Patent:

49689851, Nov 6, 1990

Filed:

Jun 6, 1988

Appl. No.:

7/202882

Inventors:

Charles M. Riggle - Colorado Springs CO

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

H03M 742

US Classification:

341106

Abstract:

A data demodulator assigns a binary value to the signal recorded in a transition cell based on the amplitude of the signal in the transition cell, the amplitudes of the signal in adjacent transition cells and system experience in categorizing how recording non-linearities and system noise effect the signals. The demodulator samples a selected number of times the recorded signal in the transition cell for which a binary value is to be determined and the recorded signal in a selected number of transition cells adjacent to that cell. It then converts the amplitude of each of the signal samples to a digital symbol. Next, it concatenates portions of the digital symbols to form an interpretation word. It uses this word to enter a stored lookup table which contains binary values, and assigns to the transition cell signal the binary value associated with the word. The table associates a value with a particular word or group of words based on system experience and the demodulation of known signals into interpretation words.

US Patent:

53771338, Dec 27, 1994

Filed:

Apr 7, 1992

Appl. No.:

7/866996

Inventors:

Charles M. Riggle - Colorado Springs CO
Nersi Nazari - Colorado Springs CO

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G06F 738

US Classification:

364736

Abstract:

An improved system and method is provided for enhanced add-compare-select (ACS) implementation which is particularly adapted to time-nesting or over-lapping of the time offsets for add and compare operations. The compare operation is implemented as a sequential bottom-up procedure whereby two numerical quantities are compared by first declaring one of the quantities as a "contingent" smaller or larger quantity. Subsequently, the least significant bits LSBs of the quantities are compared and the earlier contingent designation is retained unless the smaller of the compared bits is found to correspond to the quantity not previously designated as the "contingent" smaller quantity, whereupon the "contingent" designation is transferred to the previously un-designated quantity corresponding to the smaller of the compared bits. The process is iterated until all bit pairs in the compared quantities have been examined and the "contingent" smaller quantity remaining at that point is defined to be the "final" smaller quantity and constitutes the result of the overall compare operation. The enhanced ACS implementation compresses the computation time by almost a factor of two compared to traditional ACS implementations using top-down compare operations, without significantly affecting logic complexity of the system and eliminates the need for tie breaking.

US Patent:

57245398, Mar 3, 1998

Filed:

Apr 5, 1994

Appl. No.:

8/223378

Inventors:

Charles Michael Riggle - Colorado Springs CO
Bruce D. Buch - Westboro MA

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G06F 1200

US Classification:

395427

Abstract:

A method and apparatus for bandwidth balancing of data transfer operations between a computer and a storage subsystem are disclosed. The storage subsystem contains a number of storage devices such as magnetic disk drives. Data to be stored is supplied by the computer to the storage subsystem in the form of a transfer unit through a communication channel. The storage subsystem divides the transfer unit into a number of stripes of a pre-determined size. Each stripe is allocated to a separate disk drive whose disk surfaces are formatted into a number of track bands. Each track band is composed of several contiguous tracks associated with the same data transfer rate. Each stripe is then stored on its disk drive within a selected track band. Both data storage and retrieval from each disk drive occur at the data transfer rate associated with the accessed track band. Since all the stripes in the transfer unit are transferred to their disk drives simultaneously, the transfer operation occurs at an aggregate transfer rate equal to the sum of the individual track band transfer rates.

US Patent:

50364081, Jul 30, 1991

Filed:

May 12, 1988

Appl. No.:

7/193090

Inventors:

Michael D. Leis - Framingham MA
Bruce Leshay - Marlborough MA
Michael Muchnik - Framingham MA
Satish Rege - Groton MA
Charles M. Riggle - Colorado Springs CO

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G11B 509

US Classification:

360 48

Abstract:

A disk drive system provides all required synchronization, positioning, validation, and data functions within each disk sector. All of these functions are provided within two zones, a header section and a data section. The header section includes a preamble, a synchronization character and an address field, as well as servo information for track following. The data section of each sector includes a data preamble, a data synchronization character, a bad sector bit map, the data and data redundancy information. The header section of at least one sector in a track includes a short DC-erase field, a transitionless segment which is used in synchronization. To synchronize a read/write head to the disk, the system first detects the DC-erase field. The system next searches for the header premable and synchronization character. If it finds them within predetermined times, it then looks for a valid sector address to complete the synchronization.

US Patent:

46225161, Nov 11, 1986

Filed:

Jun 16, 1983

Appl. No.:

6/505047

Inventors:

Patrick L. Hearn - Acton MA
Charles M. Riggle - Colorado Springs CO
Shyam C. Parikh - Stow MA
Kenneth F. Veseskis - Hudson MA

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G01P 346

US Classification:

324163

Abstract:

A magnetic tachometer for generating a signal as a function of the velocity of a transducer positioning arm in a disk drive. The tachometer is formed by a pair of fixed parallel coils separated by a distance sufficient to allow a magnet, attached to a counterbalance portion of the rotary positioning arm, to move therebetween and thus to generate a voltage as a function of the velocity of the magnet. The coils are each wound over a thin armature member which is saturated by the magnet's magnetic field and they are differentially coupled to produce common mode rejection.

US Patent:

51345323, Jul 28, 1992

Filed:

Oct 30, 1990

Appl. No.:

7/607768

Inventors:

Peter R. Svendsen - Colorado Springs CO
Charles M. Riggle - Colorado Springs CO

International Classification:

G11B 555
G11B 2108

US Classification:

360106

Abstract:

A disk drive system which has a plurality of disks and a plurality of transducing head positioning across. The arms are mounted about common shaft for independent notation to desired radial position on the disk.

US Patent:

50161318, May 14, 1991

Filed:

Apr 26, 1989

Appl. No.:

7/343907

Inventors:

Charles M. Riggle - Colorado Springs CO
Peter R. Svendsen - Colorado Springs CO
John D. Read - Monument CO

Assignee:

Digital Equipment Corporation - Maynard MA

International Classification:

G11B 555

US Classification:

360106

Abstract:

A balance-moment head positioner includes a rotor assembly which rotates about a central shaft. The rotor assembly supports at the same axial location a current-carrying coil, arms for the heads, and a counterweight such that the positioner is dynamically balanced with its center of gravity at the center of rotation. The coils are arranged with legs parallel to the central shaft on diametrically opposite sides of the assembly. In addition, the positioner includes magnets and an elongated U-shaped magnetic pole member with ends facing the coils at the same axial location at the arms. Thus the torque developed when current flows through the coil, and a reactive counter-torque developed by the rotating mass coincide, substantially eliminating all torsion in the shaft, and there is no net force on the shaft.