| 摘要 |
PURPOSE: To provide a magnetic storage device which is immune to illegal data, through-put decrease, error-rate worsening, and an uncorrectable error occurrence. CONSTITUTION: This information storage device has a means for recognizing how often the overwrite has been done when overwrite-recording on the same data sector, and the device changes and records a code of code modulation or an initial value of scramble according to the number of times of overwritings. The above modulation code has the same code rate so that the data length does not vary at each recording. A number corresponding to the present modulation code of each data sector is stored in memory, and at the same time, the number is recorded in the data sector on the medium as an additional bit. When reproducing the data, the modulation code number on the memory is compared with that in the medium, and reproducing operation is carried out only when they are coincident. When they are not coincident, they are made to coincide with each other through offset reproduction, and then the reproducing operation is carried out.
|
