Hewlett-packard Company

Hoyle L Curtis

Terry L Loseke

Disclosed is an apparatus and method for defining magneto-optical disk media and an optical data storage device that allows the media to be convertible from writable to read-only. The media has a media descriptor table contained within a control track which is modified to define the media as a new media type. Previously manufactured drives will not recognize the media type, and therefore, will not read or write the media, so the data on the media is protected from being destroyed by such drives. The invention also defines a storage state bit within each sector of each track of the media, that defines whether the sector is writable or read-only. With this bit set into the writable state, the sector can be written many times. Once the bit is changed to read-only, however, the sector can no longer be written. The data storage device of the invention will not reset the bit, once it is set to the read-only state. The invention defines two locations for the storage state bit. In one embodiment of the invention the storage state bit is located in the sector mark field area of each sector, prior to the data portion of the sector. In a second embodiment of the invention, the storage state bit is placed in the data field area of each sector. Using the above described apparatus and method, the invention provides the same level of security as current WORM drives.

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Loveland, CO, United States of America

Hoyle L Curtis