8-bit to 9-bit code conversion system and 8/9 converter

摘要

An 8/9 code conversion system (11) for performing the code conversion of 8-bit data into 9-bit data, the 8/9 code conversion system being characterized in that a pair of conversion tables (A1,A2) which are differentiated based upon whether the digital sum variation (DSV), which indicates the direct current balance of the 9-bit data after their code conversion, is positive or negative. The appropriate conversion table (A1,A2) is selected in accordance with the positive or negative polarity of the integrated DSV value, which is updated at the time of each conversion. The code conversion is then performed in such a manner that the integrated DSV value converges on zero.