Set Extended Processor Exception Handler Vector (Real Mode)
Sets the address of the client's protected mode handler for the
specified real mode exception.
AX = 0213H
BL = exception/fault number (00H-1FH)
CX:(E)DX = selector:offset of exception handler
if function successful
Carry flag = clear
if function unsuccessful
Carry flag = set
AX = error code
|8021H||invalid value (BL not in range 00H-1FH)|
- CX:(E)DX does not specify a real-mode segment:offset. The reason
is that this function allows a client to set the address of an
exception handler which will receive control in protected mode when
the specified exception occurs in real mode (i.e. the host will
provide an implied mode switch for the purposes of servicing the
exception, then return to real mode after the handler exits).
- Real mode exceptions are sent to the primary client of the virtual
machine. (See Appendix A: Glossary for definition of primary
- Refer to the rules for descriptor usage in Appendix D.