Computer system with enhanced docking support

Abstract

A computer system including a programmable bridge logic device to disable various peripheral device functions is disclosed. The bridge logic device preferably includes an address decoder and one or more peripheral bus controllers. The address decoder preferably includes a configuration disable unit comprising one or more programmable status bits. Each status bit is associated with a particular peripheral device function, such as a IDE or USB functions. When a status bit is set, configuration cycles to the function corresponding to that bit are disabled. In one aspect of the invention, the computer system comprises a laptop computer that can be docked to an expansion base. The laptop and the expansion base may duplicate one or more functions. When docked, the status bit in the bridge device associated with a function also provided in the expansion base is set disabling the duplicate function in the laptop in favor of the function in the expansion base. In this manner, only the peripheral device function in the expansion base is enabled, avoiding confusion to the computer system. When the bridge device receives a configuration cycle targeting a peripheral device function, the address decoder determines whether the status bit associated with that function is set. If the bit is indeed set, indicating that function is disabled in favor of expansion base, the bridge device does not claim the cycle. The CPU, or other device that initiated the cycle determines that the cycle has not been claimed by the bridge device and tries the cycle on the expansion base. If that function is available in the expansion base, then the CPU enables that expansion base peripheral for operation.