Abstract: A peripheral interface system and apparatus including a pair of integrated circuits, referred to as a system adapter and a socket controller, use a communication protocol, referred to as a windowed-interchip-communication protocol, to interface peripherals, such as PCMCIA cards or infrared devices, and other subsystems having different formats with a CPU system bus. The system adapter communicates to a hard disk drive subsystem using the ATA communication standards to interface an ATA hard disk drive with the CPU system bus. Communication between the system adapter and the socket controller, which communicates with PCMCIA peripheral cards and IR peripherals, is accomplished using the windowed-interchip-communication protocol which may share hardware resources with other communication protocols. Communication between the system adapter and the hard disk drive and between the system adapter and the socket controller may be provided on the same chain of a standard 40 signal ribbon cable.