INT 31H 0213H: Set Exception Handler Vector (Real Mode)

                                                    Compatibility: DPMI 0.9+ 
 Expects: AX    0213H
          BL    exception number (00h-ffH)
          CX:DX (or CX:EDX) selector:offset of exception handler
 Returns: CF    NC (clear) if successful; else AX = DPMI Error Code
    Info: Sets the address to handle a specified CPU exception, when that
          exception occurs while the CPU is in real mode.

          Note that CX is a protected mode selector.  When a CPU exception
          occurs while in real-mode, the host switches to protected mode
          and calls this address.

See Also: DPMI API
          INT 2fH: Multiplex Interrupt
          DOS Functions