| 摘要 |
PURPOSE:To observe a clear waveform having no jitters by generating a trigger signal for waveform display just before a flaw position which is stored previously on a magnetic disk medium. CONSTITUTION:When an index signal is inputted first, the contents of a counter 1 are cleared. Then a signal written on the magnetic disk medium is read out and inputted as a clock signal to the counter 1, which counts up. When the flaw position is encountered and the flaw position detecting circuit of a measuring instrument generates an error signal, the signal is used as a latch signal to store the current positioned data in a register 2. When the magnetic disk medium further make one round and an index signal is generated again, the position data on the flaw part which is stored in the register 2 is loaded in a counter 3, which counts down. Thus, the counter 3 counts down successively and outputs a borrow signal in counting down to 0. This borrow signal is used to generate the trigger signal just before the flaw position.
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