User's Manual

THE 80286 U\lSTRUCTION SET
Ir Instruction Byte Format
"mod" Field Bit Assignments
mod
Displacement
00
DISP - 0(2), disp-Iow and disp-high are absent
01 OISP - disp-Iow sign-extended to 16-bits, disp-high is absent
10 OISP - disp-high; disp-Iow
11 rIm is treated as a "reg" field
"r" Field Bit Assignments
16-Blt (w - 1) B-Blt (w - 0)
Segment
000
AX 000 AL
001 CX 001 CL
010
OX 010 OL
011 BX 011 BL
100 SP 100 AH
101 BP 101 CH
110 SI 1100H
111 01 111 BH
"rim" Field Bit Assignments
rim
000
001
010
'011
100
101
110
111
OISP follows 2nd byte of ,instruction (before data if required).
NOTES:
, ,1. Opcode indicates presence and size of immediate field.
Operand Address
(BX) + (SI) + OISP
(BX) + (01) + OISP
(BP) + (SI) + OISP
(BP) + (01) + OISP
(SI) +OISP
(01) + OISP
(BP) + 0ISP(2)
(BX) + OISP
2. Except If mod-OO and r/m-110 then EA-disp-high: disp-Iow.
Figure B-2_ Ir Instruction Byte Format
8-4
00 ES
01 CS
10 SS
11 OS