The RPC project group is investigating high performance communication network interface structures which are compatible with existing operating systems, in this instance SunOS 4.1 Unix. The use of parallel processing in the marshalling and unmarshalling of RPC arguments together with direct I/O to and from the user's data area and early scheduling of user processes, are expected to give a higher throughput than more traditional implementations. The network front end comprises PC based TRAM's. The Unix machine is a Sun SPARC1+ running SunOS 4.1.3. The interconnection between the two systems is by the SCSI bus. To implement this structure requires a kernel device driver to act as a bridge between the Unix environment on the SPARC station and the TRAM's in the PC. This report describes the structure and implementation of this device driver, showing the design adopted to provide multiple rpc interfaces over a single SCSI bus