Today's FPGA technology allows reconfigurable hardware to be integrated into standard PC hardware. A hardware like this allows for on-the- fly reconfigurable hardware. It is possible to remove and insert complete subsystems just by reinitializing the configurable components. These systems make new demands on software that often can't be fulfilled by the classical device driver concept used in today's operating systems.This paper presents a flexible and on-the- fly reconfigurable hardware subsystem for interworking systems. Furthermore, a software integration for fast and efficient reconfiguration of the hardware is introduced. It provides a flexible integration into a Unix environment.