Browse Prior Art Database

Testing of Read-Only Optical Disks

IP.com Disclosure Number: IPCOM000039788D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Arter, NK: AUTHOR [+3]

Abstract

The manufacturing quality of read-only optical disks is checked by reading a disk, manipulating the data to generate the intended image of the disk's data, and then comparing that data to the originally read data, one track at a time. This scheme eliminates the need to maintain files containing billions of data bits. A fault which is common to a number of disks indicates that a faulty stamper was used to manufacture the disk. The disk to be tested is inserted into drive 10, and read into computer memory 11. Thereafter, this raw data image is corrected, using an error correction code. The resulting correct data image is stored in memory 12. The computer now generates a pseudo disk image in memory 13.

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Testing of Read-Only Optical Disks

The manufacturing quality of read-only optical disks is checked by reading a disk, manipulating the data to generate the intended image of the disk's data, and then comparing that data to the originally read data, one track at a time. This scheme eliminates the need to maintain files containing billions of data bits. A fault which is common to a number of disks indicates that a faulty stamper was used to manufacture the disk. The disk to be tested is inserted into drive 10, and read into computer memory 11. Thereafter, this raw data image is corrected, using an error correction code. The resulting correct data image is stored in memory 12. The computer now generates a pseudo disk image in memory 13. This pseudo image includes the original disk's entire data image, track by track, including all sector identifiers, track identifiers, gaps, data encoding, etc. The disk is now read again, and its entire image, i.e., the disk's data and the track identifiers, etc., is compared, bit by bit, to the pseudo image. In this way, any defect, in any part of the disk, is identified. An analysis program also provides a summary of the measured bit error rate and the mean error length.

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