Microprocessor User's Manual

2-29
OVERVIEW OF THE 80C186 FAMILY ARCHITECTURE
Figure 2-12. Memory Address Computation
The displacement is an 8- or 16-bit number contained in the instruction. The displacement gen-
erally is derived from the position of the operand’s name (a variable or label) in the program. The
programmer can modify this value or explicitly specify the displacement.
A1015-0A
CS
0000
0000
0000
0000
SS
DS
ES
Assumed Unless
Overridden
by Prefix
Explicit
in the
Instruction
Encoded
in the
Instruction
Single Index Double Index
or
or
or
Physical Addr
Effective
Address
BX
BP
SI
DI
or
or
or
BX
BP
or
SI
DI
or
EU
BIU
Displacement
+
++
++