Set Processor Exception Handler Vector

Sets the address of a handler for a CPU exception or fault,
allowing a protected mode application to intercept processor
exceptions (such as segment not present faults) that are not
handled by the DPMI host and would otherwise generate a
fatal error.  This function should be avoided by DPMI 1.0
clients (see Notes).

Call With:

   AX     = 0203H
   BL     = exception/fault number (00H-1FH)
   CX:(E)DX= selector:offset of exception handler

Returns:

   if function successful
   Carry flag= clear

   if function unsuccessful
   Carry flag= set
   AX     = error code
           8021H   invalid value (BL not in range 0-1FH)
           8022H   invalid selector

Notes:

o  The value passed in CX should  be a valid protected mode
   code (executable) selector, not a real mode segment
   address.
o  32-bit clients must supply a 32-bit offset in the EDX
   register.  If the client's handler chains to the next
   exception handler, it must do so using a 32-bit interrupt
   stack frame.
o  Every exception is first examined by the DPMI host.  If
   the host does not handle the exception, it reflects the
   exception to the first handler in the protected mode
   exception handler chain.  See page 30 for a complete
   discussion of the environment and responsibilities of
   protected mode exception handlers installed with this
   function.
o  Clients which run under DPMI 1.0 should use Int 31H
   Functions 0212H and 0213H to set the addresses of
   exception handlers.  This function is supported by DPMI
   1.0 hosts solely for compatibility with DPMI 0.9.
o  Refer to the rules for descriptor usage in Appendix D.