Source : Free On-Line Dictionary of Computing

D-type
     
        1.  A type of computer peripheral connector so named
        because one side is shorter (with one less pin) than the other
        giving a (squarish) "D" shape.  The connectors have two rows
        of pins (or holes).  Common types are 25-way (13+12 pins) and
        9-way (5+4 pins).  They are often used for serial lines,
        especially {EIA-232}.
     
        (1995-01-05)
     
        2. {D-type flip-flop}.