assembly language 1 introduction

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Assembly Language

Introduction

Sahar Mukhairez


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Introduction

At the beginning use of computer, Machinelanguage ML is used for computer programmingwhich is understood directly by the machine

without the use of interpreters. Machine language is stored in binary as a

combination of zeros and ones (0s, 1s) tocompose an instruction of 8bit (1 byte).

Later, programmers define a simple humanreadable language, instead of ML. This languageis called Assembly.


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Assembly Language

Assembly is a low level programming language

consists of a series of instruction each instruction

represents one machine instruction.

Assembler is a utility program that converts

source code programs from assembly language

into machine language.

Linker is a utility program that combinesindividual files created by an assembler into a

single executable program.


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Converting Source into Executable

Files

Source

fileCompiler

Assembler

file

Object

fileAssembler

Linker

Source

fileCompiler

Assembler

file

Object

fileAssembler

Sourcefile Compiler Assemblerfile ObjectfileAssembler

Program

library

Program

library

Executable

file

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Basic System Components

The basic operational design of a computer systemis called its architecture.

Computer System has three major components:

the central processing unit (or CPU), memory, and

input/output (or I/O). The way a system designer

combines these components impacts system

performance.

The CPU is where all the action takes place. Allcomputations occur inside the CPU.


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Basic System Components


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Is Assembly Language Portable?

Assembly language is not portable because it isdesigned for a specific processor family.

There are a number of different assembly

languages widely used today, each based on a

processor family.

Some well-known processor families are Motorola

68x00, x86, SUN Sparc, Vax, and IBM-370.

In this course, we will talk about AssemblyLanguage for x86 Processors that focuses on

programming microprocessors compatible with

the Intel IA-32 and AMD x86 processors running

under Microsoft Windows.


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Architectures

x86 (including Intel IA-32)

HP/Compaq Alpha AXP

Sun SPARC

Sun UltraSPARC

Motorola 68000

PowerPC

PowerPC64

ARM

Hitachi SuperH IBM S/390 and zSeries

MIPS

HP PA-RISC

Intel IA-64

AMD x86-64

H8/300

V850 and CRIS.

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How Does Assembly Language Relate

to Machine Language?

Machine language is a numeric language specifically

understood by a computers processor (the CPU).

All x86 processors understand a common machine

language. Assembly language consists of statements written

with short mnemonics such as ADD, MOV, SUB, and

CALL.

Assembly language has a one-to-one relationshipwith machine language: Each assembly language

instruction corresponds to a single machine-language

instruction.


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Below Your Program

High-levellanguage

program in C

void swap(int v[ ], int k){int temp;temp = v[k];v[k] = v[k+1];

v[k+1] = temp;}

swap:muli $2, $5, 4add $2, $4, $2lw $15, 0($2)lw $16, 4($2)

sw $16, 0($2)sw $15, 4($2)

jr $31

Compiler

Assemblylanguage

Program(for MIPS)

00000000101000010000000000011000000000001000111000011000001000011000110001100010000000000000000010001100111100100000000000000100101011001111001000000000000000001010110001100010000000000000010000000011111000000000000000001000

Assembler

Binarymachinelanguageprogram

(for MIPS)

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When to use Assembly Language?

When you dont have the tools to program in

higher level:

New embedded processors

Compilers that check deadlines for real time system donot exist yet

When the tools fail:

Compilers still generate sub-optimal code

When you are building the tools:

Compiler designer/builders must know assembly well

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Why to use Assembly Language?

Assembly provides direct access to computerhardware, requiring you to understand much aboutyour computers architecture and operating system. Itis more powerful and more efficient than high level

languages in dealing with hardware. Assembly language has several benefits:

Speed. Assembly language programs are generally thefastest programs around.

Space. Assembly language programs are often the smallest.

Capability. You can do things in assembly which are difficultor impossible in High Level Languages.

Assembly language is an ideal tool for writingembedded programs because of its economical use ofmemory.


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Booting process

What is booting?

The process of starting or restarting a computer

cold boot

Process of turning ona computer after it

has been powered off

completely

warm boot

Process ofrestarting a

computer that isalready powered on

Also called a warmstart

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Booting process

processor

BIOS

hard disk

CD-ROM drive

(RAM) memorymodules

CMOS

floppy disk drive

Step 6

expansion cards

How does a personal

computer boot up?

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How does a personal computer boot

up?

Step 1: The power supply sends a signal to

components in the system unit.

Step 2: The processor looks for the BIOS (BasicInput/Output system)

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up?

Step 3: The BIOS performs the POST, which

checks components such as the mouse, keyboard

connectors, and expansion cards. (Power On Self

Test)

Step 4: The results of the POST are compared

with data in the CMOS chip. (battery power)

Step 5: The BIOS looks for the system files in drive

A (floppy disk drive) and then drive C (hard disk).

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up?

Step 6: The boot program loads the kernel of

the operating system into RAM from storage

(hard disk).

The operating system in memory takes control of

the computer.

Step 7: The operating system loadsconfiguration information and displays the

desktop on the screen.

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up?

The operating system executes programs in

the StartUp folder

Registry - Several files that contain the system

configuration information

Registry is constantly accessed during the computer's

operation

StartUp folder - Contains a list of programs that

open automatically when you boot the computer

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Loading Operating System

CPU

Bus

Main

MemorySecondary

Memory

DiskRAMCPU

Bus

OS


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Loading Application from HD to

Memory by OS

App

DiskRAMCPU

Bus

OSApp

App

DiskRAMCPU

Bus

OS

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