| 摘要 |
PURPOSE: To make it possible to easily detect formatted blocks and decide their validity by coping with a format entity pattern by using a programmable corresponding threshold value in each required mode. CONSTITUTION: In a read-only (R) mode and a read-while-write(RWW) mode, PLL 40 of a block/validity detection system 36 detects a synchronous character, and at the same time, a burst detection logic circuit 42 detects an interblock gap (IBG), a synchronous burst, by using a threshold value of a parameter/ threshold circuit 48. These detection patterns are decided as valid for threshold values higher than the detected ones from the circuit 48 by the individual logic circuits 64-66 of synchronization, IBG, and burst qualification, and when the validity are not satisfied, a status message requesting forΘ-block rewrite is generated, and it is possible to easily detect blocks and decide their validity.
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