Disclosed is a communication control device whose configuration is capable
of being changed flexibly without being affected by a computer's internal
bus specifications, etc. Externally to the computer, a plurality of
communication adapters are connected to a serial bus. This serial bus is
compliant with the USB or the IEEE 1394 standard. A program for
implementing part of protocol layer functions is downloaded from the
computer to each communication adapter. The computer, using an
application, implements the function of an upper layer in the protocol
layer stack, and the adapters each implement part of the protocol layer
functions using the downloaded program, and together they support a
communication protocol.
