Abstract: In electronic devices such as combination CD-ROM and MP3 recorder/players power is conserved by buffering audio or visual data in a solid state memory, preferably of the FLASH or DRAM type, before writing the data to a rotating hard disk. Alternatively, audio and/or visual data, including musical works and still pictures and video, read from a rotating hard disk may be buffered in the same solid state memory while being played. By rotating the hard disk drive only for transfer of audio-visual data, which is normally compressed, in blocks, the hard drive may be stopped both during relative lengthy accumulation, and/or use, of this data, and energy conserved.