Set Extended Processor Exception Handler Vector (Real Mode)

Call With

AX = 0213H
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 00H-1FH)
8022H	invalid selector

Notes

• 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 client.)

• Refer to the rules for descriptor usage in Appendix D.