Douglas G Gray

US Patent:

54446856, Aug 22, 1995

Filed:

Jun 1, 1994

Appl. No.:

8/252377

Inventors:

Shakeel Masood - Sunnyvale CA
Douglas G. Gray - Santa Clara CA

Assignee:

Advanced Micro Devices, Inc. - Sunnyvale CA

International Classification:

G11B 1928

US Classification:

369 47

Abstract:

In a normal sector mark detection routine, using a wide open search window bits read from an optical data disk are searched for the presence of a sector mark pattern. Following detection of the pattern, using a search window of programmable width, a predefined region of the next sector is searched to locate a sector mark pattern. If the pattern is found, a sector mark found signal is generated. If the pattern is not found, a pseudo sector mark signal is generated. This sequence is repeated until either a subsequent sector mark pattern is detected, a predetermined number of pseudo sector mark signals generated or an exit command is received. Data is read from a sector in response to a sector mark found signal or pseudo sector mark signal. In a constant sector mark mode, the disk is searched, with the window wide open. Sector mark patterns are detected continuously to carry out media certification.

US Patent:

48111244, Mar 7, 1989

Filed:

Jul 24, 1987

Appl. No.:

7/077252

Inventors:

Vineet Dujari - Sunnyvale CA
Nicos S. Syrimis - Santa Clara CA
Douglas G. Gray - Santa Clara CA

Assignee:

Advanced Micro Devices, Inc. - Sunnyvale CA

International Classification:

G11B 2700
G11B 2012

US Classification:

360 49

Abstract:

A novel technique for skipping defects on a magnetic or writable optical disk is described. The technique includes a sector format comprising a header (24) and data area (28), wherein the data area can include one or more "bad areas" (108, 116) which will be skipped when data is being written to or read from the sector. The bad areas are variable in size and may be located anywhere in the data area, including in an EDAC. The header includes a defect descriptor (48) comprising a defect pointer (70, 72) for each of the bad areas supported. Each defect pointer contains a value (74, 78) indicating the number of bytes in the good data area (106, 114) preceding the bad area pointed to by the defect pointer, and a value (76, 80) indicating the number of bytes in the bad area. The value indicating the number of bytes in a good area is set to a value indicating a number of bytes at least as large as the sector size if there is no subsequent bad area in the data area.