| 摘要 |
A phase change overwrite system that reduces the phase change material flow which results from the repeated overwrites of the same data on the media. Two techniques can be used to solve the overwrite degradation problem. The first is to exploit the fact that a given data sequence can be represented by multiple bit patterns. This choice in bit patterns is primarily for use in reducing the low frequency content of the bit pattern. However, some of the choice available may be used for other purposes, such as ensuring the same bit pattern is not always used. The second technique is to vary the point in the bit pattern at which writing begins. This is possible in a ROM type format because the new data are written in exactly the same location as the old data. Therefore, if the old data are exactly the same as the new data, it is optional whether or not to overwrite the old data. Note that typically the header information for old and new data is the same. Accordingly, this opportunity for varying the location of where writing begins is available even when the new user data are completely different from the older data.
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