Instruction Set Architecture and Design - Fundamentals of Computer Organization and Architecture - page 26

TABLE 2.2 Summary of Addressing Modes

Addressing
mode Definition Example Operation

Immediate Value of operand is included in

the instruction

load #1000, R i R i 1000

Direct
(Absolute)

Address of operand is included
in the instruction

load 1000, R i R i M[1000]

Register
indirect

Operand is in a memory
location whose address is in
the register specified in the
instruction

load (R j ), R i R i M[R j ]

Memory
indirect

Operand is in a memory
location whose address is in
the memory location
specified in the instruction

load (1000), R i R i M[1000]

Indexed Address of operand is the sum

of an index value and the
contents of an index register

load X(R ind ), R i R i M[R ind þ X]

Relative Address of operand is the sum

of an index value and the
contents of the program
counter

load X(PC), R i R i M[PC þ X]

Autoincrement Address of operand is in a

register whose value is
incremented after fetching
the operand

load (R auto ) þ , R i R i M[R auto ]

R auto R auto þ 1

Autodecrement Address of operand is in a

register whose value is
decremented before fetching
the operand

load 2 (R auto ), R i R auto R auto 2 1

R i M[R auto ]

2.3. INSTRUCTION TYPES

The type of instructions forming the instruction set of a machine is an indication of
the power of the underlying architecture of the machine. Instructions can in general
be classified as in the following Subsections 2.3.1 to 2.3.4.

2.3.1. Data Movement Instructions

Data movement instructions are used to move data among the different units of the
machine. Most notably among these are instructions that are used to move data
among the different registers in the CPU. A simple register to register movement
of data can be made through the instruction

MOVE R i ,R j