A computer subsystem of a computer includes a CPU, RAM, display, storage device, input device(s), and a digital-audio generating IC. A CD-ROM subsystem of the computer includes a CD-ROM drive and CD-ROM control buttons for controlling CD-ROM drive's operation while playing audio CDs. An audio-interface IC of the CD-ROM subsystem couples a bus of the computer subsystem to the CD-ROM drive, and to the control buttons. The audio-interface IC, in one operating mode, relays commands and data between the bus and the CD-ROM drive. A second operating mode permits turning the computer subsystem off while the audio-interface IC autonomously responds to the control buttons and transmits commands to the CD-ROM drive for playing an audio CD.