A data transfer protocol encapsulates legacy transport protocols (e.g., TCP/IP, UDP/IP, IPX/SPX, etc.) for transfer of data over a memory mapped, high-speed serial bus conforming, to the IEEE 1394 standard. The data transfer protocol is implemented as a databus manager layer interposed between the 1394 bus and an existing network layer (e.g., SCSI, Ethernet, FDDI, token ring, etc.). A databus manager resides at every node on the 1394 bus. Each databus manager has an array of memory cells to temporarily hold discrete data units transferred over the serial bus from a remote node. Each databus manager also has a cell availability register and a cell servicing register. The cell availability register holds information indicating whether one or more remote memory cells at the remote node are available to receive a data unit to be transferred over the serial bus. The cell servicing register holds information indicating whether one or more of the local memory cells are ready to be serviced.
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