Intel 80287 - Page 308

THE 80286 INSTRUCTION SET
PROTECTED MODE EXCEPTIONS
#GP(O) if the operand is in a non-writable segment. #GP(O) for an illegal memory operand effective
address in the CS, DS, or ES segments;
#SS(O) for an illegal address in the SS segment.
REAL ADDRESS MODE EXCEPTIONS
Interrupt 13 for a word operand at offset OFFFFH.
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