Disk Erasure Method for Direct Access Storage Device
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
This invention relates to a method for effectuating a complete erasure of a set of (d,k) RLL-encoded transitions written on the tracks of a cyclically reusable recording device. The recording device is of the type wherein all number patterns applied thereto become (d,k) RLL-code converted and recorded. The method comprises the step of rewriting the entire extent of the tracks with the (d,k) RLL-encoded image of a suitably applied and shifted permutative number pattern (ABCCABBCA) selected to yield the highest density RLL code transitions per track extent. The (d,k) parameters typically are (2,7) for which a fortuitous permutative number pattern is (2,4,9). The rewriting of the entire track extent includes those portions of a track containing known defects and over which writing would have ordinarily been suspended.