1. Computer Organization & Assembly Language
Instructor: Nausheen Majeed

2. Course Objective To understand organization of a computer system
To gain an insight knowledge about the internal architecture and working of microprocessors.
To understand working of memory devices, interrupt controllers and I/O devices.
To learn Assembly Language

3. Course Contents Introduction to Microprocessors
History & Evolution of Intel Microprocessors
Organization of Intel 8086 Processor
Fetch-Execution Cycle
Microprocessor Bus Structure
Internal Memory, External Memory, Input Output Devices
Instruction Representation
Memory Organization & Structure
Memory Addressing
Cache
Interrupts, DMA
Pipelining

4. Contd.. Introduction of Assembly Language:
Data Declaration
Loop and Jump
Using Arithmetic and Logical Instructions
Using Shift and rotate instructions
Input / Output and display text
Stack and operations on stack
Subroutine and Procedures
Interfacing with High level languages
Overview of Debugger and practice of writing and debugging programs
Using EMU8086 to write and test assembly language programs
Introduction to Microcontroller Programming

5. Text Books
Assembly Language programming and Organization of the IBM PC by Ytha Yu and Charles Marut.
Computer Organization and Architecture, William Stallings
Kip Irvine, “Assembly Language for Intel-Based Computers”, Third Edition,, Prentice Hall Incorporated

6. Outline Introduction to Computer Organization
An Introduction to Microprocessors
History of Intel 8086 Microprocessors
An Introduction to Assembly Language

7. Introduction

8. What is Computer Organization?
Organization is how features are implemented.
How does a Computer Work?
For Example: Is there a special hardware multiply unit for multiplication operation or is it done by repeated addition?

9. Structure & Function
Structure is the way in which components relate to each other
Function is the operation of individual components as part of the structure.
Main functions performed by a computer system are:
Data processing
Data storage
Data movement
Control

10. Contd..
When data is received from or delivered by a device that is directly connected to the computer, process is called Input-Output (I/O).
When data are moved over longer distance, to or from a remote device, the process is known as Data Communication.

11. Structure - Top Level Computer Peripherals Central Main Processing
Unit
Main
Memory
Computer
Systems
Interconnection
Input
Output
Communication
lines

12. Structure - The CPU CPU Arithmetic Computer and Registers Login Unit
I/O
System
Bus
CPU
Internal CPU
Interconnection
Memory
Control
Unit

13. Structure - The Control Unit
CPU
Sequencing
Logic
ALU
Control
Unit
Internal
Bus
Control Unit
Registers and
Decoders
Registers
Control
Memory

14. Microprocessors

15. Microprocessor
Microprocessor is an electronic circuit that functions as the central processing unit (CPU) of a computer, providing computational control.
Microprocessors are also used in other advanced electronic systems, such as computer printers, automobiles, and jet airliners.

16. Processor Integration
Early computers had many separate chips for the different portions of a computer system
Registers
ALU
Memory
Control

17. CPU (ALU + Reg + control)
Microprocessors
Data Bus
CPU (ALU + Reg + control)
Address Bus
Memory
I/O
Devices
Control Bus
First microprocessors placed control, registers, arithmetic logic unit in one integrated circuit (one chip).

18. Modern Processors I/O Memory Devices
Modern microprocessors (general purpose Processors) also integrate memory onchip for faster access. External memory and I/O components still required. Memory integrated on the microprocessor is called cache memory.
Data Bus
CPU
Address Bus
Registers, ALU, Fetch, Exe Logic, Bus logic, Cache Memory
Memory
I/O
Devices
Control Bus

19. Microcontrollers
Microcontrollers integrate all of the components (control, memory, I/O) of a computer system into one integrated circuit. Microcontrollers are intended to be single chip solutions for systems requiring low to moderate processing power.
Microcontroller

20. Microprocessor vs. Microcontroller
CPU is stand-alone, RAM, ROM, I/O, timer are separate
designer can decide on the amount of ROM, RAM and I/O ports.
general-purpose
Microcontroller
CPU, RAM, ROM, I/O and timer are all on a single chip
fix amount of on-chip ROM, RAM, I/O ports
single-purpose

21. History of Intel Microprocessors
First microprocessor
All CPU components on a single chip
4 bit
Followed in 1972 by 8008
8 bit
Both designed for specific applications
Intel’s first general purpose microprocessor

22. Pentium Evolution (1)
8080
first general purpose microprocessor
8 bit data path
Used in first personal computer – Altair
8086
much more powerful
16 bit
instruction cache, prefetch few instructions
8088 (8 bit external bus) used in first IBM PC
80286
16 Mbyte memory addressable
up from 1Mb
80386
32 bit
Support for multitasking

23. Pentium Evolution (2) 80486 Pentium Pentium Pro
sophisticated powerful cache and instruction pipelining
built in maths co-processor
Pentium
Superscalar
Multiple instructions executed in parallel
Pentium Pro
Increased superscalar organization
Aggressive register renaming
branch prediction
data flow analysis
speculative execution

24. Pentium Evolution (3) Pentium II Pentium III Pentium 4 Itanium
MMX technology
graphics, video & audio processing
Pentium III
Additional floating point instructions for 3D graphics
Pentium 4
Note Arabic rather than Roman numerals
Further floating point and multimedia enhancements
Itanium
64 bit

25. Assembly Language

26. Programming Languages
High-Level Languages (HLL)
Assembly Language
Machine Language

27. High-Level Language
Allow programmers to write programs that look more like natural language.
Examples: C++, Java, C#.NET etc
A program called Compiler is needed to translate a high-level language program into machine code.
Each statement usually translates into multiple machine language instructions.

28. Machine Language The "native" language of the computer
Numeric instructions and operands that can be stored in memory and are directly executed by computer system.
Each ML instruction contains an op code (operation code) and zero or more operands.
Examples:
Opcode Operand Meaning
40 increment the AX register
add 0005 to AX

29. Assembly Language
Use instruction mnemonics that have one-to-one correspondence with machine language.
An instruction is a symbolic representation of a single machine instruction
Consists of:
label always optional
mnemonic always required
operand(s) required by some instructions
comment always optional

30. Sample Program Written in Debug

31. Figure 1. Machine Language Generation by ASM and HLL programs.

32. Why Learn Assembly Language?
Learn how a processor works
Explore the internal representation of data and instructions
Allows creation of small and efficient programs
Provides a convenient way to directly access the computers hardware
Programmers write subroutine also known as Interface Subroutine / device drivers in assembly language and call them from high-level language programs.

33. Essential Tools
Assembler is a program that converts source-code programs into a machine language (object file).
Linker joins together two or more object files and produces a single executable file.
Debugger loads an executable program, displays the source code, and lets the programmer step through the program one instruction at a time, and display and modify memory.
Emulator allows you to load and run assembly language programs, examine and change contents of registers. Example: EMU8086

34. References
Chapter 1 & 3, Ytha Yu and Charles Marut, “Assembly Language Programming and Organization of IBM PC”,
Chapter 3, William Stallings, “Computer Organization & Architecture”
Chapter 1, Kip Irvine, “Assembly Language for Intel-Based Computers”, Third Edition,, Prentice Hall Incorporated