Source : Free On-Line Dictionary of Computing

compute server
     
         A kind of {parallel processor} where the
        parallel processors have no I/O except via a bus or other
        connection to a {front-end processor} which handles all I/O to
        disks, {terminals} and network.
     
        In some antiquated {IBM} {mainframe}s, a second CPU was
        provided that could not access I/O devices, known as the slave
        or attached processor, while the CPU having access to all
        devices was known as the master processor.
     
        (1995-03-19)