| 摘要 |
PURPOSE:To detect miscorrection at the time of error correction and to prevent an error correcting circuit previously from miscorrection by comparing the code length with the data length and finding AND of a signal forming code length < data length and a correctable signal. CONSTITUTION:When correcting operation is started, a counter 3 is cleared and an ECC code generator 1 is shifted by a clock so that the input terminal (a) of an AND gate 11 becomes ''1''. When the input terminal (a) is turned to ''1'', correcting data is outputted from the lower bit of the ECC code generator 1. The output of a counter 3 is inputted to a comparator 12 and compared with the data length and a signal indicating the size relation between the code length and the data length is inputted to the input terminal (b) of the AND gate 11. If the value of the counter 3 is larger than the data length, the input terminal (b) is turned to ''1'', the AND gate 11 is turned on and a correctable signal is generated. If the value of the counter 3 is smaller than the data length, the input terminal (b) is turned to ''0'' and an uncorrectable signal is outputted. |
