Battery information is transmitted from a recording and playback apparatus
to a host computer. In the host computer, based on the time for which operation
can be continued, corresponding to the current operating status and the remaining
battery level, which is stored in battery information, a warning is output, the
data of a cache memory is written, data writing prohibition is set, and a forced
closing process is performed. With this construction, in a system formed of a recording
and playback apparatus, such as a CD-R/RW drive unit and a personal computer, a
proper system operation corresponding to the remaining battery level of the recording
and playback apparatus is obtained, and the data recorded in the recording medium
is prevented from being destroyed as a result of operation stopping due to, for
example, the remaining battery level becoming zero.
