Computer Architecture and Organization - Addressing Modes 2, Study notes of Computer Architecture and Organization

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Unit-1: Addressing Modes



Recap



Session Objectives & Teaching Learning Material



Session Plan



Introduction to Addressing modes



Algorithm, Advantages and Disadvantages

◦ Implied

◦ Immediate

◦ Direct

Indirect

◦ Register Direct

◦ Register Indirect



Assignment



References

OutLine

Session Objectives

◦ To teach the instruction set category based on

addressing modes and types addressing modes

that enable the students to visualize the

internal operations of various addressing

modes

Teaching Learning Material

◦ LCD, White board Marker, Presentation slides

Objectives & Teaching

Learning Material

Session Plan

Time

(in min)

Content

Learning Aid

and

Methodology

Faculty

Approach

Typical

Student

Activity

Skill and

Competency

Developed

Re-Cap

Quiz

Presentation

Questions

Organizes

Answers

Identifies

Knowledge

Evaluation

Assembly

Language

programming

Explains Presentation Listens Application

Computation of

performance

factors

Explains

Presentatio

n

Listens Analytical

10 Drawing graphs Explains

Presentatio

n

Observes Synthesis

Conclusion and

Summary

Summary Facilitates

Listens

Participates

Comprehensio

n

Immediate Addressing Mode

Opcode

Opcode

The simplest form of addressing is immediate addressing

Example:- MOVE #100H, R

Here the data 100h is moved to R1.

MVI A, 01

• MVI stands for Move Immediate. This basically implies move

01 to A.

Advantage:

This mode can be used to define and use constants

or set of initials values of variables.

No memory references

Advantage:

Limited Operand size

data is a part of instruction itself.

Operand

Operand

Direct/Absolute Addressing Mode

Opcode

Opcode

The address where data is available is part of the instruction

Example:- MOVE 30A4, R

• (^) The memory location 50A4 is accessed
• (^) The data from this location is copied onto Register R1.

Advantage:

Large operand Magnitude

Disadvantage:

Limited Address Size

The change in the location of the program is

associated with the change in all absolute memory

references.

The address field contains th effective address of the operand.

EA

EA

Main Memory

Operan

d

Register Direct Addressing Mode

Opcode

Opcode

The only difference is that the address field refers to a register

rather than a main memory address

Example:- MOVE R2, R

• (^) The content of register R2 is copied into register R

Advantage:

No memory Reference

Disadvantage:

Limited number of registers

Register addressing is similar to direct

addressing

R

R

Registers

Operan

d

Register Indirect Addressing Mode

Opcode

Opcode

Register indirect is just analogous to indirect addressing in

the both cases; the only difference is whether the address

field refers to memory location or a register.

Example:- MOVE (R2), R

The content of address availble in register is copied into

Register R

Advantage:

Large address space

Disadvantage:

Extra memory space

(R)

(R)

Main Memory

Operan

d

Registers

EA



You are asked to collect a instruction set of any

processor and categorize them based on

Addressing modes.

( Note: There are 160+ processors are there. So

that no two students should select same

processor. )

Assignmet

Text Book

William Stallings “Computer Organization

and architecture” Prentice Hall, 7th edition,

References