Abstract: A method and apparatus are provided for thermal asperity detection in a direct access storage device. A data signal is received from a data channel in the direct access storage device. A level threshold comparator compares data samples of the data signal with a selected level threshold. Consecutive zero level data samples are detected. Responsive to each identified data sample above the selected level threshold and not an identified consecutive zero level data sample, a counter value is incremented. The counter value is compared with a predefined count threshold. A thermal asperity event is identified responsive to the counter value above the predefined count threshold.

Abstract: A data encoding method and apparatus are provided for implementing a predefined rate code, such as a 16/17 rate code for a data detection channel in a direct access storage device. A binary data stream is received and sequential symbols of the received binary data stream are identified. Sequential alternate symbols of the binary data stream are encoded into first codewords. Sequential alternate other symbols are encoded into second codewords. The alternating first and second codewords are sequentially combined. For a rate 16/17 rate code, the first codewords include 9-bit codewords and the second codewords include 8-bit codewords. The second 8-bit codewords are either raw symbols of the received binary data stream or remapped symbols of the received binary data stream. All likely error events are limited to within three consecutive bytes in a user data stream with a 16/17 rate code of the preferred embodiment.