Intel 80286

THE 80286 INSTRUCTION SET
Table B·1. ModRM Values
Rb
=
AL CL
OL BL AH CH OH BH
Rw
=
AX CX OX
BX
SP
BP
SI 01
REG
=
0
1
2 3 4
5
6 7
ModRM values
Effective address
00 08 10 18
20 28
30 38
[BX +
SI]
01 09 11 19 21 29 31
39
[BX +
01]
02 OA 12 1A 22 2A 32 3A [BP + SI]
mod=OO
03 OB 13 1B 23 2B 33 3B [BP + 01]
04
OC 14 1C
24
2C
34
3C [SI]
05
00 15 10 25
20 35 30 [01]
06
OE 16 1E 26 2E
36 3E
016 (simple var)
07
OF 17 1F 27 2F 37
3F [BX]
40 48
50
58 60 68
70 78
[BX + SI] + OS(l)
41 49 51
59
61
69
71 79
[BX + 01] + OS
42 4A 52 5A 62 6A 72 7A
[BP + SI] + OS
mod=01
43 4B 53 5B 63 6B 73 7B [BP + 01] + OS
44 4C 54 5C 64
6C
74 7C
[SI] + OS
45 40
55
50 65 60 75 70 [01] + OS
46 4E
56
5E 66 6E 76 7E
[BP] + DS(2)
47 4F 57
5F
67 6F 77 7F [BX] + D8
SO 88 90
98
AO AS BO BS
[BX + SI] + 016(3)
81 89
91
99
A1
A9
B1
B9 [BX + 01] + 016
S2 8A 92 9A A2 AA B2 BA
[BP
+SI] + 016
mod=10
S3 SB
93
9B
A3 AB B3 BB [BP + 01] + 016
S4 SC 94 9C A4 AC B4 BC
[SI] + 016
S5 SO 95 90 A5 AO B5 BO
[01] + 016
S6 SE
96 .
9E A6 AE B6 BE
[BP] + 016(2)
87 SF 97 9F A7 AF B7 BF [BX] + 016
CO CS 00 OS EO ES FO FS Ew=AX Eb=AL
C1 C9 01 09 E1 E9 F1 F9 Ew=CX Eb=CL
C2
CA 02 OA E2 EA
F2
FA
Ew=OX
Eb=OL
mod=11
C3 CB
03 OB
E3 EB
F3 FB Ew=BX Eb=BL
C4
CC
04
OC
E4
EC
F4
FC Ew=SP
Eb=AH
C5 CO 05 00 E5
EO
F5
FO
Ew=BP Eb=CH
C6 CE 06 OE E6 EE F6 FE Ew=SI Eb=OH
C7
CF 07 OF E7 EF F7 FF
Ew=OI
Eb=BH
NOTES:
1. OS denotes an 8-bit displacement following the ModRM byte that is sign-extended and added to the
index.
2. Oefault segment register is SS for effective addresses containing a BP index; OS is for other memory
effective addresses.
3. 016 denotes the 16-bit displacement following the ModRM byte that is added to the index.
B-3
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