Method and apparatus for accessing target data in a data storage medium

An apparatus for accessing target data in a data storage medium having sequentially arranged data sectors recorded therein, each of the data sectors containing at least identification data, an identification error detection code and main data, said apparatus comprising:

• a pick-up head adapted for reading one of the data sectors recorded in the data storage medium;
• a demodulator coupled to said pick-up head and operable so as to demodulate said one of the data sectors to generate a block unit that contains the identification data, the identification error detection code and the main data of said one of the data sectors, and that further contains an inner-code parity for the block unit;
• an error correction code decoder coupled to said demodulator and operable so as to verify accuracy of the identification data in the block unit, said error correction code decoder enabling said demodulator to generate the block unit for a succeeding one of the data sectors recorded in the data storage medium when the identification data in the block unit for a current one of the data sectors is found to be inaccurate;
• said demodulator being under the control of said error correction code decoder to enable said pick-up head to find a target data sector that corresponds to starting location of the target data in the data storage medium with reference to the block unit having accurate identification data, and to read the data sectors recorded in the data storage medium in sequence starting from the target data sector;
• said demodulator demodulating the data sectors from said pick-up head to generate the corresponding block units;
• and
• a data buffer coupled to said demodulator for storing the block units generated thereby to form a block in said data buffer;
• said error correction code decoder being further coupled to said data buffer and being further operable so as to decode the block formed in said data buffer.