CD-ROM decoder

摘要

A CD-ROM decoder for decreasing the load on a microcomputer. The CD-ROM decoder stores in a buffer memory in sector units digital data. The CD-ROM decoder includes a check head register for storing a first address of the buffer memory when storing the processed digital data in the buffer memory. A check sector counter counts the number of sectors of the processed digital data stored in the buffer memory to generate a count value. A command decision circuit decides whether digital data requested to be transferred is stored in the buffer memory based on the first address, the count value, and a head address of the digital data. The command decision circuit permits the CD-ROM decoder to transfer the processed digital data when deciding that the digital data requested to be transferred is stored in the buffer memory.