Int 09  - CPU-generated (80286,80386) - Processor Extension Protection Er  [C]

Desc:  called if the coprocessor attempts to access memory outside a segment
     boundary; it may occur at an arbitrary time after the coprocessor
     instruction was issued

Note:  until the condition is cleared or the coprocessor is reset, the only
     coprocessor instruction which may be used is FNINIT; WAIT or other
     coprocessor instructions will cause a deadlock because the
     coprocessor is still busy waiting for data

See Also: INT 07"CPU"