| 摘要 |
PURPOSE:To prevent the lowering of the use efficiency of a magnetic disc device, by detecting an address mark again without stopping the operation when a flaw on the surface of a recording medium is mistaken for the address mark. CONSTITUTION:When an address mark detecting instruction is inputted from a terminal AM, this instruction passes through a NOR circuit 1 to set a terminal S of a flip flop 2 to ''0'' and set an output terminal SAM to ''1''. A data read signal is inputted from a terminal DATA, and the output of an AND circuit 3 becomes a signal DATA, and an AM detecting circuit 4 starts detecting an address mark AM. When a skip defect SD is mistaken for the address mark AM, a terminal AFN of the AM detecting circuit 4 becomes ''0'', and a terminal AFN' becomes ''1''. Consequently, the flip flop 2 is reset, and the terminal SAM becomes ''0''. A counter 5 starts counting bytes with byte clocks; and when five bytes are counted, a flip flop 6 is set, and a terminal SBS is set to ''1''. |
