System for sharing human-computer interface of a legacy device with expansion units

摘要

A system for sharing a human-computer interface between a legacy device and an expansion unit for supplementing operation of the legacy device includes a logic device configured to selectively route input and output signals between the human-computer interface and the legacy device or the expansion unit. The expansion unit monitors input signals from the human-computer interface for control codes designating usage of the human-computer interface by either the expansion unit or the legacy device. The logic device includes a switching device that selectively decouples inputs from the human-computer interface from the legacy device during usage of the interface by the expansion unit to isolate the legacy device from input signals not intended for the legacy device.