Source : Free On-Line Dictionary of Computing

raw mode
     
         A mode that allows a program to transfer
        {bits} directly to or from an {I/O} device without any
        processing, abstraction, or interpretation by the {operating
        system}.
     
        Systems that make this distinction for a disk file are
        generally regarded as broken.
     
        Compare {rare mode}, {cooked mode}.
     
        [{Jargon File}]
     
        (2002-04-14)