PURPOSE:To reduce the circuit scale used for an optical card, a magnetooptical disk, a DAT, by multiplying an output of an EXOR circuit by alpha (m) times and latching each output thereof the a register by different clocks, in an encoding/decoding circuit in a field for correcting an error. CONSTITUTION:Syndromes S0-S3 are constituted of a bus line, and a clock CK and an OE (output enable) are used so as to complete with each other among the syndromes S0-S3. Therefore, the clock and the OE used for each of the syndromes S0-S3 are controlled by a signal shown in the figure. The clocks CKB1, 3, 5 and 7 are inversion signals H L and L H of CK1, 3, 5 and 7. In this way, as for an input J, it is necessary to input it in synchronism with the clock CK1 at every ji. Also, SCL is a signal which becomes L, when a first receiving word j1 is inputted. In this way, in a syndrome S, its S0-S3 are outputted at every four periods, and at every SCL, the final answer is generated.
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