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Browse Prior Art Database

Programmable Write Equalizer

IP.com Disclosure Number: IPCOM000037711D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Karp, JM: AUTHOR

Abstract

Write equalizers are digital filters used to alter phase and frequency characteristics of recorded data on disk, tape and optical storage products.

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Programmable Write Equalizer

Write equalizers are digital filters used to alter phase and frequency characteristics of recorded data on disk, tape and optical storage products.

Three-term write equalizers alter the write data output based upon the present data bit (Yn), the last data bit (Yn-1), and the next data bit (Yn+1) to be written. This incoming pattern determines the output write data pulses to be written.

The output data bit cell is divided into two half-cells, ø1 and /2 . At the beginning of each half-cell, the logic must produce a pulse in the opposite direction of the last pulse (Toggle), or in the same polarity (same). This circuit uses two eight bit registers and two eight-to-one multiplexers to make this toggle logic completely flexible under microcode control for both half-cells /1 and ø2 . This circuit can, for example, write 3480 data pulses and 441 or 423 pulses. This allows the same circuit to be backward compatible with existing products under microcode control.

Any 3-term write equalizer can be implemented with this circuit. This includes 3480 code and follow ons, and the write equalizer is easily modified "on the fly" by the microprocessor. This allows the circuit to write tapes of different formats under microcode control.

Disclosed anonymously.

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