Patent ID: 7245575

Claim:
A method for overwriting data in a storage device, wherein data bits are represented by at least one of a presence and an absence of pits formed at a plurality of bit positions on a storage surface, the plurality of bit positions being spaced such that writing a pit at each bit position can cause a previously-written pit within r bit positions to be erased, where r is a predetermined number 1, the method comprising: coding data such that successive bits of a value x in a coded bit sequence are separated by at least d bits of value x , where d is a predetermined number r; reading an amount of an old bit sequence to be overwritten by the coded bit sequence sufficient to locate at least one excess pit, wherein each excess pit is a pit not within r bit positions of a bit position where a coded bit of the value x is to be recorded; writing, at respective bit positions, each pit required to erase each excess pit in the old bit sequence; and writing, at respective bit positions, each pit required to maintain a pit at each bit position where the coded bit of the value x is to be recorded.