Hewlett-packard Company

Erik R Habbinga

Mark Millican

Lawrence Nathaniel Taugher

Kenneth G Richardson

Mark E Nash

Kerry J Monroe

Mark E Mills

Stephen G Uhlmann

Christian J Warling

William P Repasky

Steven G Hall

Thomas L Bloom

Tod Earhart

A circuit and method for generating write compensated write data signals in magnetic data recording. The circuitry is programmable to enable generation of write compensation meeting a variety of write compensation specifications. In particular, the circuitry can be programmed to generate extra write pulses, to adjust the pulse width and to adjust the pulse spacing within data cells. In an example embodiment, an input waveform drives a reset input on a state machine. An output waveform shape is stored as a pattern of bits in a register. The state of the state machine determines which register bits are selected by a multiplexer for output as a new write compensated write data signal.

Programmable write equalization for magnetic data recording

A method for reliably measuring preformatted servo patterns, on a magnetic tape, for positioning a magnetic head. The tape has constant frequency stripes marking servo pattern areas. The drive reading the preformatted tape has a read channel amplifier with automatic gain control (AGC). When a stripe is detected, AGC is enabled. Before leaving a stripe, AGC is placed on hold. The amplitudes of two servo bursts are then measured with a gain that has been calibrated by a signal from a stripe. During the time AGC is enabled, the amplifier peak output is limited to less than half the maximum amplifier peak output. The servo pattern signal amplitude is about twice the signal amplitude of a stripe, so that servo patterns are measured with almost the maximum signal-to-noise ratio. When a stripe is detected, a counter counts pulses resulting from the stripe signal, for a fixed time, to ensure that the stripe detection is valid. If the stripe is qualified, the servo pattern measurements are used for head alignment adjustment. If the strip is not qualified, the servo pattern measurements are discarded.

Accurate measurement of preformatted track servo patterns by a magnetic

A digital line driver circuit with active pull-down, high transient pull-up current, and limited steady-state pull-up current. Steady-state pull-up current is provided through a pull-up resistor. Transient pull-up current is provided by a capacitively coupled active pull-up circuit.

Logic output circuit with high transient pull-up current

Growing community of inventors

Longmont, CO, United States of America

Erik R Habbinga