CSA

NAME: FABIAN TERWASE MWAR

TP NUMBER: TP032588

COURSE CODE: CE00215-M-CSA

INTAKE CODE: UCMF1310COM

ASSIGNMENT TITLE: COMPUTER SYSTEMS ARCHITECTURE.

SUBMISSION DATE: 26TH MAY, 2014

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TABLE OF CONTENT

1.0 Introduction……………………………………………………3

1.1 Brief history of computers……………………………………4

1.1.1 First generation computers………………………………..5

1.1.2 Second generation computers……………………………5

1.1.3 Third generation computers……………………………….

1.1.4 Fourth generation computers……………………………..

1.1.5 Fifth generation computers………………………………..

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1.0 INTRODUCTION

Computer systems are made of both the hardware and software. For a computer

to work as a computer, the hardware and software systems must be integrated.

The neglect of either of the two can lead to massive failures. The PC has much

great success because of the Windows Operating System (Rob Williams 2006).

The information system of a computer is made up of different components. They

include:

Data element which is the fundamental representation of facts and

observations. Information is gotten from data that is processed by the

computer system.

Hardware element which is the physical components of a computer

system that process data through the execution of instructions. It accepts

data through the input device and makes information available to users

through the output devices.

The software element which forms the instructions that are executed by

the hardware element. This controls the workings of the computer.

The communication element which provides the ability to share processing

operations and data among various computers and to their users. This is

done both locally and remotely.

“The combination of hardware, software, communication and data make up the

architecture of a computer system. The architecture of a computer system is

remarkably similar whether the system is a play station, a personal computer that

sits on your lap while you work, an embedded computer that controls the

functions in your cell phones or in your car, or a large mainframe system that is

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never actually seen by the hundreds of users who access it every day” Irv

Englander, 2010.

The computer systems we use today are built on the concepts of the first

mainframe computers.

1.1 BRIEF HISTORY OF COMPUTERS

One cannot talk about computers without its history. How it all started from the

early days where it was basically only just seen as a calculating device, it went

through processes of evolution through the years up to what we have now where

computers are involved in just about every facet of human existence. This is

because what we use today all started just as a calculator and has gone through

about five generations of computers. The generations are important to discuss

here because it shows how we got having embedded chips in washing machines,

microwave ovens just to mention a few. They will be discussed just briefly just to

keep things in perspective.

By generation, it simply means the different stages of changes the computer

went through, the improvements made to it over the years. With every generation

of the computer, the circuit has become smaller and has been made more

advanced than in the previous generation. This has in more ways than one

greatly increased the power, speed and memory of the computer system. The

generations include:

First generation computer – Vacuum tubes

Second generation computer – Transistors

Third generation computer – Integrated circuits

Fourth generation computer – Microprocessors

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Fifth generation computer – Present day computer where focus is on Artificial

Intelligence and also Cloud Computing.

1.1.1 FIRST GENERATION COMPUTER

First generation computers made use of the vacuum tube as their circuit and

used magnetic drums for memory. These were very large computers, they could

take up a whole room or an entire building because they were enormous in size.

Computers in this generation include, ENIAC- Electrical Numerical Integrator And

Calculator which was the first generation purpose computer that was ever built.

EDSAC- Electronic Delay Storage Automatic Calculator, EDVAC- Electronic

Discrete Variable Automatic Computer, UNIVAC- Universal Automatic Computer

and IBM 701. They were mainly used for scientific computations. They consumed

more power but had limited performance and of course were very expensive and

difficult to assemble.

1.1.2 SECOND GENERATION COMPUTERS

The second generation computer made use of the transistors. Transistors used

discrete transistors in place of vacuum tubes which helped control the heat that

was the case with the previous generation and it increased reliability and less

bulk. Transistors generally regulate flow of electrical current. They were invented

by Bell Telephone Laboratories. These computers have the same components

as the modern computer, they had printouts, operating systems, were able to

store programs, they were smaller in size, had more speed (milliseconds to

microseconds), they used assembly language for programming. They used

magnetic tapes and disks for secondary storage. They were less expensive

compared to previous generation.

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They were used in businesses, research centers, inventory control, governments,

and universities.

1.1.3 THIRD GENERATION COMPUTERS

The second generation computer was a major improvement on the first but they

still could generate much heat that could damage computer internal parts. The

third generation was made to eliminate that via the use of an integrated circuit

where electronic components were combined on a small silicon disk. This was

developed by Jack Kilby who was an engineer.

These landmark achievement means engineers were able to combine more

components on a single chip which was called semiconductor. Computers

became smaller as more components were squeezed onto a single chip. These

changes means more speed and efficiency was attained. The third generation

computers had key boards where users could interact with the computer rather

than through the use of punched cards and printouts. They also had monitors

and the hardware and software was interfaced with an operating system (UNIX)

which enabled the computer to run different applications at the same time.

This also marked the first time computers were accessible to the general public

due to the fact that they were smaller in size and were far less expensive

compared to the first two generations.

1.1.4 FOURTH GENERATION COMPUTERS

The introduction of microprocessors ushered in the fourth generation computers

where thousands of integrated circuits were built onto a microchip. This brought

about the microcomputers. The fourth generation computers used VLSI- Very

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Large Scale Integration circuits where over 5000 transistors and other circuitry

elements were built on a single chip.

This generation of computers was more compact, highly reliable, had more

speed and above all was very affordable. These gave birth to the personal

computer (PC). The introduction of the microprocessors helped as different items

could now be embedded with these chips and they could be used as computers.

The internet also became part of the computer. There was the introduction of the

mouse and other computer handheld devices.

1.1.5 FIFTH GENERATION COMPUTERS

The VLSI technology was turned into ULSI- Ultra Large Scale Integration

technology. This brought about microprocessors which had over tens of million

electronic elements built onto the chip. It is based on Artificial Intelligence which

is still basically in the development stage. It aims to make computers work and

behave like human beings.

1.2 MICROPROCESSORS

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Microprocessor is the core of the technologies that we enjoy today. They help

process information in different computing aspects down to monitoring real time

systems. Without the microprocessors, it will be fair to say to say that,

communication through telephones, online means, etc. both at home, our work

places and even the businesses we undertake daily from our comfort zones

won’t have being easy if not impossible in most cases.

This is because, all of the electronic devices we use for our everyday needs

contain an inbuilt microprocessor embedded in them. Be it the cash registers

used in banks, traffic light control system, the laser jet printers we use in our

homes and offices, automated washing machines, refrigerators, the computers

(desktop and laptop), in our weather stations, the airplanes, televisions and so

many other appliances. All these devices won’t work with much efficiency and

speed if it’s not for these microprocessors.

Since the inception of microprocessors that changed the way computers are

used, a range of microprocessors have being made. In 1965, the co-founder of

Intel, Gordon Moore predicted that, the number of transistors on a chip would

double about every two years. His law has proved right over the years as Intel

has exponentially increased the number of transistors integrated into its

processors which enhances greater performance and energy efficiency. The

processor is usually referred to as the brain of the computer.

1.3 MICROCONTROLLERS

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In embedded systems, what is usually used is called microcontroller. A

microprocessor is a part of this microcontroller. They are a small silicon chip

which is part of the integrated circuit and contains a processor core, memory and

also has a programmable input and output hardware. These microcontrollers are

designed for embedded applications which are used for only for specific

functionality. The application software is copied or burned unto the read only

memory (ROM) of the microcontroller for the one specific task and it does only

that function only. A microcontroller is a compact microcomputer designed to

govern the operation of embedded systems in motor vehicles, robots, office

machines, complex medical devices, mobile radio transceivers, vending

machines, home appliances, and various other devices. A typical microcontroller

includes a processor, memory, and peripherals. Depending on the power and

features that are needed, you might choose a 4, 8, 16, or 32 bit microcontroller.

Standard microprocessors (such as the Motorola 68000 or National 32032) are

some of the most frequently used as powerful embedded microcontrollers.

Here is a brief look at the various Intel microprocessors powering different

computer systems, some of which are also used in embedded systems.

Intel 4004 microprocessor was introduced in 1971

Initial clock speed 108 KHz, number of transistors 2300

Intel 8008 microprocessor was introduced in 1972

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Initial clock speed 500-800 KHz, number of transistors 3500, this was twice as

powerful as the 4004

Intel 8080 microprocessor was introduced in 1974

Initial clock speed 2 MHz, number of transistors 4500, this very microprocessor

made video games and home computers possible.

Intel 8086 microprocessor was introduced in 1978

Initial clock speed 5 MHz, number of transistors 29000, this was the first 16bit

processor and had ten times the performance of the previous processors.

Intel 8080 microprocessor was introduced in 1979

Initial clock speed 5 MHz, number of transistors 29000, this was important at the

time because it ushered in the IBM personal computer.

Intel 286 microprocessor was introduced in 1982

Initial clock speed 6 MHz, number of transistors 134,000, this was the first

processor that could run all the software written by its previous predecessors.

Intel 386 microprocessor was introduced in 1985

Initial clock speed 16 MHz, number of transistors 275,000, first microprocessor to

run multiple software programs at the same time.

Intel 486 microprocessor was introduced in 1989

Initial clock speed 25 MHz, number of transistors 1,200,000, this microprocessor

introduced the floating point unit.

Intel Pentium processors was introduced in 1993

Initial clock speed 66 MHz, transistors 3,100,000, this microprocessor could

execute 112million commands per second which allowed computers to easily

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incorporate real word data such as speech recognition, sound, handwriting and

images.

Intel Pentium Pro microprocessor was introduced in 1995

Initial clock speed 200 MHz, number of transistors 5,500,000, this

microprocessor brought about dynamic execution which made it possible for the

advanced 3D visualization and other interactive capabilities.

Intel Pentium II and Intel Pentium II Xeon microprocessor was introduced

in 1997

Initial clock speed 300 MHz, number of transistors 7,500,000.

Intel Pentium III and Intel Pentium III Xeon microprocessor was introduced

in 1999

Initial clock speed 500 MHz, number of transistors 9,000,000, these

microprocessors were able to execute internet streaming and could conserve

power during idle times.

Intel Pentium 4 was introduced in 2000; Intel Xeon microprocessor was

introduced in 2001

Initial clock speed 1.5 GHz, number of transistors 42,000,000, these

microprocessors ushered in the Nano technology age.

Intel Pentium M microprocessor was introduced in2002

Initial clock speed 1.7 GHz, number of transistors 55,000,000, these were

designed for portable computing and they brought about the network

connectivity.

Intel Pentium D microprocessor was introduced in 2005

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Initial clock speed 3.2 GHz, number of transistors 291,000,000. This features first

desktop dual core design with two complete microprocessors and each can run

at the same speed in one physical package.

Intel Core” 2 Duo processor; Intel Core 2 Extreme processor; Dual-Core

Intel Xeon processor was introduced in 2006

Initial clock speed 2.93 GHz, number of transistors 291,000,000. Intel Core 2

processor optimizes mobile microarchitecture.

Dual Core Intel Itanium 2 processor 9000 series was introduced in 2006

Initial clock speed 1.66 GHz, number of transistors 1,720,000,000. This

processor doubled the performance of previous Itanium processors while also

reducing the average power consumption.

Quad-Core Intel Xeon processor (penryn);

Dual-Core Intel Xeon processor (penryn);

Quad-Core Intel Core 2 Extreme processor (penryn) was introduced in 2007.

Initial clock speed >3GHz, number of transistors 820,000,000. This improved

video, imaging and 3D content performance and also new power management

features.

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2.0 COMPUTER CLASSIFICATION BASED ON PURPOSE.

Computers are classified based on their purpose. There are two categories

based on purpose.

General Purpose computers

Specific or Special Purpose Computers.

2.1 GENERAL PURPOSE COMPUTERS

These computers have wide spread applicability and usage. Because of their

flexibility in usage and applications, one computer can perform multiple functions

such that were never thought about at the time they were being manufactured.

The computer has become such a big part of human interaction mainly because

of the flexibility of the general purpose computers. They are built for a variety of

processing applications. Different software is used to accomplish different tasks.

These different tasks may include, controlling an organizations security system,

home security, it may include word processing, database manipulation. Industries

use general purpose computers to track manufacturing inventories. General

purpose computers are also used in educational institutions to keep track of

students’ records, in hospitals with machines such as respirators performing

different functions to save lives. They are equally used for scientific calculations

and a lot more.

This is mostly made possible because of the microprocessors. When one

watches a 3D movie, it is because the need for speed and capacity needed for

such applications is made possible microprocessors such as the Quad-Core Intel

Xeon processors and Intel Premium Pro processors and so many other

microprocessors that perform so many other functions, most of which I

mentioned earlier on. Smart phones and tablets are embedded with the new Intel

Atom processors which help them perform a variety of tasks which include

texting, listening to music, watching movies, playing of games, sending and

receiving emails and a lot of other functions imaginable.

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Three Examples of General Purpose Computers

Personal Computers (PC) – Dell Inspiron 5323

The Tablet PC

Smart Phones

2.1.1 Personal Computer – Dell Inspiron 5323

Functions:

The personal computer is used for typing (word processing). It is also

used for browsing the internet, playing music, watching movies.

It is used for storing data and files and applications.

It is used for connecting with friends and family through social networks.

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The computer generally has four basic functions which are input,

processing, output and storage. It does what you command it to do

whenever you want it to all depending on installed programs and software.

How was the task performed by PCs accomplished before its inception?

In the case of word processing, manual typewriters were used.

The use of television set which was mostly black and white, radio sets

were used for music.

For storing files and data, documents were saved in office files in paper

form on the shelves in the office buildings.

For connecting with family and friends, the use of hand written letters and

then they would be posted out.

Type of microprocessor and operating system

Dell Inspiron PC uses Intel CORE i3 2.6GHz clock speed as its processor and

uses Windows 8.1for its operating system. There are so many other processors

used by desktop and laptop computers most of which I mentioned earlier and a

lot more I did not mention.

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2.1.2 The Tablet

Functions: The functions of the tablet are similar to that of a laptop PC. Some of

the most conspicuous differences are the fact that it uses a pen instead of a

mouse and the fact it can be folded to unlike the desktop or laptop. It is highly

convenient to carry about as it can easily fit into a pocket. Another important

difference is, the tablet can be connected wirelessly to a projector unlike the

other PCs. It also can be used as a notebook in classes and can be used as a

wireless sharing tool for network.

How was the task performed by the Tablet accomplished before its

inception?

Uses of desktop and laptop PCs, mouse are used on the PCs in place of the pen

and wires were used to connect projectors.

Processors and operating system

Intel Core processor, Intel Atom processors, clock speed 1.6GHz are good for

efficient performance of the tablet on Windows 8. Of course they use so many

processors too and other Windows operating systems.

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2.1.3 Smart Phones

Functions:

Smart phones can be used just like a personal computer. And they can be used

to send and receive emails, make and receive calls, used for movies, to play

music, they can be connected to a printer to and documents could be loaded to

the printer for printing just the same way you use the PC system. Smart phones

are equally used to connect through social media; they are used as TV remote

controls. The functions are too numerous to mention. It is a Personal computer in

your pocket.

How was the task performed by Smart phones accomplished before its

inception?

Obviously, these tasks were being done by the desktop and laptop PCs.

Processors and operating system

Smart phones use different kinds of processors; the HTC one family uses

Qualcomm Snapdragon 600 and Qualcomm Snapdragon 800 2.3GHz clock

speed. The operating system is android. Windows smart phones like the Nokia

Lumia uses various ARM processors and Qualcomm processors but have now

moved to Intel x86 chips. The operating system is Windows 8.

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2.2 SPECIFIC/SPECIAL PURPOSE COMPUTERS

These computers are designed for special or specific purposes only. This means,

they can only undertake a single job or operation that it was designed for. They

are designed and assigned their specific task and they perform only that and

nothing else. The problem solving capability is only narrowed to a strictly defined

range and they work with strong efficiency and precision often repeatedly and

reliably. As discussed earlier, these special purpose computers have embedded

processors called microcontrollers which are designed for such dedicated

purposes.

Specific purpose once programmed to do a certain task cannot be

reprogrammed. They can be designed to either carry out only numerical

processing task or data processing only. They mostly have preset keyboard for

the task they are designed for. Most of our home appliances are specific purpose

computers.

These types of computers are useful for traffic light control systems; they are

used in aircrafts for their navigation system, cash registers in banks. They are

used in refrigerators and much more.

Special purpose computers have all the features of general purpose computers

except that, their application to a problem are due to their functionality whereas

general purpose could be due to stored programs.

They are very fast in processing their tasks since they only perform a single one

repeatedly. The amount of memory needed in them is far less. The major

disadvantage of special purpose computers is their lack of versatility. They

cannot be used for other functions other the one they were designed for.

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Examples of Special Purpose Computers

ATM

Automated washing machine

Cash registers

Elevators

Laser jet printers

Microwave oven

Digital cameras

2.2.1 Automated Teller Machine (ATM)

How is it used?

To check account balance

To make deposits

For cash withdrawer

Cheques can also be deposited through ATM

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To make funds transfer from one account to another

Payments are made through them

To top air time on mobile devices

How was the task performed by ATMs accomplished before its inception?

Cash was withdrawn at the counters using withdrawer slip or booklet.

Cash transfer was done by requesting your bank to do so by filling forms.

Cash deposit was done through filling tellers and still is today.

Type of processors used and operating system.

Intel Pentium IV 2.8GHz embedded processor; Intel Xscale 32bit processor; Intel

Core vPro etc.

95% of ATM machines use Windows XP operating system. [1]

2.2.2 Automated Washing Machine

Functions: As the name implies, they are used for washing clothes.

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Operations: It has an agitator, inner and outer wash, tub, electric motor and has

a drain tube. It has valves, switches and a timer. Valves enable passage of hot

and cold water into washing machine. Timer for timed washing and functioning

and switches for adjustment and control of different functions.

How was the task performed by automated washing machines

accomplished before its inception?

Through the use of manual washing machines.

You could use your hands to wash.

Processors and operation system

The LG washing machine uses QuadComm snapdragon processor with 1.7GHz

Quad-Core CPU

2.2.3 Cash Registers

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Functions: A cash register is used in stores to calculate record sales

transactions. It has an attached drawer where cash is stored.

Operations: It is first programmed with date, time and tax. When items are

bought, the user will enter the value of items and it will calculate the total amount

and deduct tax and print out the receipt. It will save the records afterwards and

reset for the next usage.

How was task performed before its inception?

Cash and other sales records were recorded and stored in cash inventories in

books.

Processors and Operating System

Intel 8051 microcontroller (MCS-51 family), 60,000 transistors, CPU 4KB ROM,

128 RAM, 32bit I/O pins, serial port, two 16bit timers.

2.2.4 Laser jet Printers

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Operations: Laser jet printers use laser beams which creates an image on the

drum in the printer. When this happens, there is a change in the electrical charge

in the drum, the drum then rolls to the toner. The toner is then transferred to the

paper by a combination of pressure and heat and it then prints the content that is

sent in.

Functions: Used for printing, photocopying, scanning and some cases used as a

fax machine.

Operating system and processor

They are compatible with almost all operating systems available in the market.

Be it Windows XP, 7, 8, Linux, etc.

Uses most microcontrollers such as PMC-Sierra’s MIPs TM processor 250MHz;

PMC-Sierra’s RISCMark 7000, 64bit Super Scaler microprocessor with

integrated L2 cache; Intel 386 and above works well with these printers.

2.2.5 Elevators

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Functions: They are used to lift people or cargo from one point to another

usually in a vertical direction up and down.

Operations: Two types of elevators exist, the hydraulic and rope elevators. The

hydraulic elevator uses cylinder, piston, fluid reservoir, a rotary pump and

hydraulic fluid. They all combine to push the piston with the help of a

programmed microcontroller up and down depending on the levels the

passengers decide.

Processors and operating system

Motorolla MC68CH11 A1 microcontroller.

2.2.6 Microwave Oven

Operations: The see through oven door is open, the food or drink that is to be

heated is then placed on the ceramic tray which sits on the roller ring inside the

oven and then the door is closed back. The control panel which has predefined

keys is then used to control the amount of heat to use and time it could take for

the heating process. When the process is done, it goes off automatically and the

door opens.

Functions: Used for heating or warming of drinks and meals

Processor and operating system

They make use of the Intel 8051 microcontroller.

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2.2.7 Digital Camera

Functions: They are used to capture images and moments. Some digital

cameras also can be used as camcorders.

Processors and operating system

Intel MCR 296 16bits 50MHz clock speed microcontroller is used in most digital

cameras. Intel 80296 SA microcontroller.

3.0 HOW COMPUTER LANGUAGE DECODE FROM HIGHLEVEL LANGUAGE

TO SYMBOLIC AND FINALLY TO BINARY CODE.

Programs are a set of instructions used by the computer to execute applications

in order to solve problems. A programming language is a formal computer

language which provides communication instructions for a computer. The two

main types of programming languages are, low level and high level programming

languages.

Low level languages: These are used by the different computer hardware to

communicate with each other. They are machine oriented and usually require an

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extensive knowledge of the computer configuration. Two low level languages

exists which are the machine and assembly language.

Machine language uses binary codes which are written as a string of 1s and 0s.

This is the language understood by the computer that does not require

translation. Instructions are written in codes such as

11100010101000110100011100011. This is however difficult for humans to

understand, hence the need to use assembly languages.

Assembly language uses letters and symbols. An assembler is used to

translate it into machine understandable codes for the computer to be able to use

them. They use terms like MOVE, ADD, SUB, END, etc. instead of the usual 1s

and 0s.

High level languages: They use real English and mathematical symbols like +,-,

%,*, etc. for communication. Languages such as Java, C++, FORTRAN, etc.

which are programming languages used by programmers. Example, to write

“Hello World” in Java:

Public class MyFirstJavaProgram {

public static void main (Strings [] args) {

System.out.println (“Hello World”);

}

}

These high level languages are easier for humans to understand and use than

the 1s and 0s in binary codes. They are much closer to the logic of human

language. However the computer cannot use them directly and that is where the

use of compilers comes in (Education Portar, 2014).

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COMPILERS

When high level language is translated to machine language, compilers become

handy. Compilers are used by the computer to translate high level human

language and programmers language into machine codes which are the binary

codes understood by the computer before execution of an application. The high

level program is referred to as the source code, (Education Portar, 2014).

INTERPRETERS

The role of an interpreter in conversion of these high level languages is to make

the computer understand the high level languages. They translate high level

source codes during execution of a program, (Education Portar, 2014).

4.0 COMPUTER NETWORKS

How sending and receiving an email works with the analog and digital signal

conversion.

Sending an email from one end to another involves using the sending device

which could be a computer PC or any other capable device like a smart phone or

a tablet. First you need you need network connection to be able to achieve this.

The process works just like when you are sending a letter through the post office,

the difference here is, it uses electronic mailboxes to carry this out.

Before one is able to send an email, one need to have an email address which

you by using what is called Mail User Agent MUA. There are several examples of

MUA in use, such yahoo, Gmail, outlook, Hotmail and a whole lot of them.

Afterwards one needs to be able to compose the email and then can forward it.

The following is done using the Mail Transport Agent MTA or the Mail Delivery

Agent; they serve as the post office for emails. The mail is sent to the receivers

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MTA via the internet. Mail transport agents on both the sender and receivers side

can communicate each other the Simple Mail Transport Protocol SMTP.

Now, when an email is sent from the home computer, it connects wirelessly

through to a DSL modem and it passes onto an internet service provider ISP

through travel channels. The sent data passes through different communications

channels with different signal converters. DSL is Digital Subscriber Line modem;

it is a small physical device which provides digitized subscriber line connectivity

to the Internet and through other additional connections to a computer on the

Internet. Some DSL modem can combine the services of a router and a modem

in one, (Englander 2010, pp. 379).

Different signaling methods exist but the most commonly talked about are the

digital and analog signals. The analog signals carry continuous data of varying

wave forms. The digital carries digital signals using two values of electrical

voltage which is 1 and 0. The DSL modem mentioned above serves as a

converter of these signals usually from the senders end from digital to analog

and when it gets to the receivers end, they are converted back from analog to

digital signals.

Digital to Analog signal conversion and verse versa

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Internet

Senders Mail Client MUA

Senders Mail Server MTA

Receivers Mail Client MUA

Receivers Mail Server MTA

Company LAN

Router/Modem

Email sending and receiving process.

The signal conversion takes place in the modem (modulator) from the sender

from digital to analog signals and when it gets to the receiver, its converted

through the LAN (demodulator) back to digital signals before the receiver

retrieves it.

“Although digital transmission is favored for most use these days, analog

transmission methods are required for wireless media, such as radio and sound,

for wireless networking and for other forms of wireless data communication”,

(Englander 2010, pp. 450).

Usually the digital data is the right data but because these data travels wirelessly,

it must be converted for smooth transmission. “Digital data being carried by a

digital communication channel is already in correct format, so theoretically no

conversion is necessary. In practice, the situation is somewhat different. Since

there is no carrier present on the channel, there may be no way to detect a string

of bits at the receiving end of the channel for some signals”, (Englander 2010 pp.

460). Hence the need to convert digital signals to analog signals before they are

fully transmitted.

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Modem which converts digital signals to analog

5.0 CONCLUSION

This work talks about the history of computers as it relates to the current computers we

have in use today. The five generations of computers, this specified their different

circuits. The first generation used vacuum tubes as their circuit, second generation used

transistors, third generation made use of integrated circuits, the fourth generation was

known for the introduction of microprocessors which changed the way computers have

become so important today and also the fifth generation which involves the use of

artificial intelligence and cloud computing.

The core of this work is based of understanding the use of microprocessors in both the

general and special purpose computers and this work has gone on to give some

examples of these different computers and the processors they use with their clock

speed and in most cases the type of operating system they use. Microcontrollers which

are used in embedded systems are also discussed.

The use of compilers and interpreters in translating high level languages to machine

readable low language was also discussed as this is importing in making the computer

work as it should.

Last but not the least, the process of sending and receiving emails is discussed most

especially as it relates to the various signal conversions that usually take place. The

conversion of digital to analog signals which is necessary to enable wireless transfer of

images, sounds, etc.

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Pearson and Prentice Hall

Okoro, u., et al, 2013, Application of microprocessors, International journal

of emerging technology and advanced engineering.

Stallings, W., 2007, Data and Computer Communications. 8th Ed., New

Jersey, USA, Pearson and Prentice Hall

Williams, R., 2006, Computer Systems Architecture-A Networking

Approach. 2nd Ed. Prentice hall.

BILIOGRAPHY

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Available from, http://www.alibaba.com/showroom/wincor-atm-

embedded-processor.html, [Accessed 26th May, 2014]

2. Sadrusham, N.J.,2008, Embedded washing machine using microchip

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