(12) United States Patent
(io) Patent No.: (45) Date of Patent:
US 6,577,460 Bl Jun. 10,2003
(54) METHOD AND APPARATUS FOR
IMPROVING TRACK FORMAT EFFICIENCY
IN A DIRECT ACCESS STORAGE DEVICE
(75) Inventor: Weldon Mark Hanson, Rochester, MN (US)
(73) Assignee: International Business Machines Corporation, Armonk, NY (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
Primary Examiner—David Hudspeth
Assistant Examiner—-Varsha A. Kapadia
(74) Attorney, Agent, or Firm—Crawford & Maunu, PLLC;
Mark A. Hollingsworth
An apparatus and method for transferring data between a read/write transducer and a data storage medium provides for improved track format efficiency. Data is written to a data sector of the data storage medium using a write current waveform developed in the read/write transducer. The write current waveform is typically at one of several possible states following writing of the data to the data sector. According to the present invention, a transition pattern is generated and used for transitioning the write current waveform from the state following writing of the data to a known state consistent with coding constraints of the data channel. A predetermined data pattern associated with the known state of the write current waveform is written to a pad field of the data sector. The transition pattern and the predetermined data pattern are used to resolve detector and parity post-processor closure decisions during a sector read operation.
23 Claims, 16 Drawing Sheets