Source : Free On-Line Dictionary of Computing

Intel 486DX
     
         One of {Intel}'s {Intel 486} family of
        {microprocessors} (one of the last before the {Pentium}).  The
        486DX has a working built-in {floating point unit} (FPU).  The
        {Intel 486SX} is effectively a DX with the FPU disabled.  The
        DX has a pin to select the external {data bus} width (16 or
        32).
     
        The {Intel 487SX} is a 486DX with a 486SX pinout.
     
        (1995-05-09)