A low-power audio CD player for portable computers permits operation of
the CD-ROM subsystem when power is not being supplied to the computer
subsystem. In one embodiment of the invention, the computer subsystem
comprises a system CPU, a digital-audio generating circuit, a digital
computer bus coupling the CPU and the digital-audio generator circuit,
and a digital computer bus controller. The CD audio subsystem comprises
an audio device capable of playing an audio CD and coupled to the digital
computer bus controller, an audio amplifier circuit coupled to the audio
device, and an audio interface coupled to the digital computer bus in
parallel to the digital computer bus controller and the audio device. The
audio interface is adapted to generate signals to operate the audio
device and play the audio CD when power is not being supplied to the
computer subsystem or to the CPU. In method form, a method for playing an
audio CD in a computer system comprises deenergizing a computer CPU; and
controlling, using an audio interface coupled to a digital computer bus
in parallel to a digital computer bus controller and an audio device
capable of playing an audio CD, the audio device and a computer audio
amplifier to play an audio CD without supplying energy to the CPU.