| 摘要 |
PURPOSE:To enable high concentrated storage without containing direct current components in writing signals and to simplify an encoding and a decoding circuits by handling bit systems corresponding to continuous data with any of two, three and four bit codes, and converting the systems into any of four, six and eight bit codes where no direct current components exist at the time of modulation. CONSTITUTION:For storing data as shown in Fig. A, when the first two bit data word is coincident with any one of ''11'' and ''01'', such data word is converted into four bit code word according to a conversion list I , and when the data word does not correspond to any of them, one bit following a conversion list II is added to the data word to form three bit data words. When the data words are coincident with any of ''000'', ''001'' and ''100'', the data words are converted into six bit code words according to the conversion list II, and when the data words do not correspond to any of them, the four bit data words formed after addition of one following these data words are converted into eight bit code words according to the conversion list III. Code words as shown in Fig. B are obtained after repeating conversion of bigger bits following the four bit data words, which are modulated into NRZI to obtain writing electric current as shown in Fig. C. |
