Patent ID: 7196987

Claim:
A controller for controlling interruption and restarting data writing to a recording medium, wherein the data writing is performed by emitting a laser beam against the recording medium at a write level that is used when data read from a buffer memory is recorded on the recording medium, the controller comprising: an address memory for storing at least one of an address of the recording medium and an address of the buffer memory when the writing of data to the recording medium is interrupted, each address indicating a data location where the writing interruption occurred; a synchronizing circuit for reading the data written to the recording medium prior to the interruption by emitting the laser beam at a read level, reading the data stored in the buffer memory, and synchronizing the written data and the stored data; and a restart circuit for restarting the data writing based on the address stored in the address memory, wherein the restart circuit switches the laser beam from the read level to the write level before the restart circuit restarts the data writing.