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