| 摘要 |
PURPOSE:To read out an address mark of a record surely, by stopping the address mark detection in a certain section by an index mark. CONSTITUTION:A counter 1 is counted up by a byte clock (a) and is reset by an index mark detection signal (b). When the counter 1 counts the time from the read-out of the index mark to the time when a magnetic head reaches the last position of a data field D of a record R0, namely, the time when the magnetic head runs for a length l, the counter 1 transmits a signal to a decoder 2, and the decoder 2 transmits a pulse to an output C to reset a flip flop 3. Since the flip flop 3 is set by the index mark detection signal (b), the Q terminal falls by the index mark detection signal (b) and rises by the output C of the decoder 2. |
