41 is equal to 8 existing errors cannot be corrected by any combination of the mode a mode b and mode c signals and the control is ended as an error end in this manner eight combinations of the on off states of the mode a mode b and mode c signals are selectively determined on the basis of the counter value in the retry counter 41 it is possible to arbitrarily select any combination of the on off states of the mode a mode b and mode c signals on the basis of the counter value in the retry counter 41 for example all the mode signals are set off initially the pointer generators 62 63 and 64 are not reset in response to the detection of the the re synchronous frame in this case it is possible to add an error track pointer generator which is reset each time a request to read information again is generated it is preferable that a sequence of selecting one or more selecting generators 62 64 be directed to reducing the number of times that the request to read information again is generated in actuality some error track pointers certainly indicate the real occurrence of errors and some error track pointers indicate a.