Intel 80286

THE 80286 INSTRUCTION SET
pp/n Instruction Byte Format
ModRM
"mod" Field Bit Assignments
mod
Displacement
00
OISP = 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
"rim" Field Bit Assignments
rIm Operand Address
000 (BX)
+ (SI) + OISP
001 (BX) + (01) + OISP
010
(BP)
+ (SI) + OISP
011
(BP) + (01) + OISP
100 (SI) + OISP
101
(01) + OISP
110
(BP)
+ 0ISP(2)
111 (BX) + OISP
OISP
follows 2nd byte of instruction (before data if required).
NOTES;
1 .. Opcode indicates presence and size of immediate value.
2. Except if mod=OO and r/m=110 then EA=disp-high: disp-Iow.
Figure B-1. In Instruction Byte Format
8-2
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