Source : Free On-Line Dictionary of Computing

symmetric multiprocessing
     
         (SMP) Two or more similar {processor}s connected
        via a high-{bandwidth} link and managed by one {operating
        system}, where each processor has equal access to I/O devices.
        This is in contrast to the "{compute server}" kind of
        {parallel processor} where a {front-end processor} handles all
        I/O to disks, terminals and {local area network} etc.
     
        The processors are treated more or less equally, with
        {application program}s able to run on any or perhaps all
        processors in the system, interchangeably, at the operating
        system's discretion.  Simple MP usually involves assigning
        each processor to a fixed task (such as managing the file
        system), reserving the single main CPU for general tasks.
     
        {OS/2} currently supports so-called HMP (Hybrid
        Multiprocessing), which provides some elements of symmetric
        multiprocessing, using add-on IBM software called MP/2.  OS/2
        SMP was planned for release in late 1993.
     
        (1995-03-19)