Source : Free On-Line Dictionary of Computing

Read-Only Memory
     
         (ROM) A type of data storage device which is
        manufactured with fixed contents.  In its most general sense,
        the term might be used for any storage system whose contents
        cannot be altered, such as a gramophone record or a printed
        book; however, the term is most often applied to
        {semiconductor} {integrated circuit} memories, of which there
        are several types, and {CD-ROM}.
     
        ROM is inherently {non-volatile storage} - it retains its
        contents even when the power is switched off, in contrast to
        {RAM}.
     
        ROM is often used to hold programs for {embedded system}s
        since these usually have a fixed purpose.  ROM is also used
        for storage of the lowest level {bootstrap} software
        (firmware) in a computer.
     
        See also {Programmable Read-Only Memory}.
     
        (1995-05-09)