| 摘要 |
PURPOSE: To provide a CD-ROM decoder in which work load of a control microcomputer is reduced and format discrimination of each sector is surely conducted even when a higher operating speed is desired as a system. CONSTITUTION: A sector information converting circuit 14, which constitutes of the CD-ROM decoder, discriminates the format of each sector of CD-ROM data based on the information of headers and subheaders of CD-ROM data taken into a header information register 13 and the information on error flags of the subheaders taken into an error flag register 30. When an error flag is raised on a subheader or the front half four bytes of the subheader are equal to the back half four bytes, it is discriminated to be a mode 2 form 1 or a mode 2 form 2. When the front half four bytes of the subheader are not equal to the back half four bytes, on the other hand, it is discriminated to be a mode 2 formless.
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