Intel 80286, 80287 manual 1REG, Oreg, Fstswax, Xxx

MACHINE INSTRUCTION ENCODING AND DECODING

Table A-2. Machine Instruction Decoding Guide (Cont'd.)

	1st Byte					ASM286 Instruction
			2nd Byte		Bytes 3, 4
Hex	Binary					Format
DF	1101	1111	1100	1REG		*(7)
OF	1101	1111	1101	OREG		*(8)
OF	1101	1111	1101	1REG		*(9)
OF	1101	1111	1110	000		FSTSWAX
OF	1101	1111	1111	XXX		reserved

NOTE:

*The marked encodings are not generated by the language translators. If, however, the 80287 encounters one of these encodings in the instruction stream, it will execute it as follows:

(1)FSTP STeil

(2)FCOM STeil

(3)FCOMP STeil

(4)FXCH STeil

(5)FCOMP STeil

(6)FFREE STeil and pop stack

(7)FXCH STeil

(8)FSTP STeil

(9)FSTP STeil

A-5