Introduction to Computers and Computing

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COMPUTING AND HISTORY OF COMPUTERS

What is a computer?

A computer has no single definition as it can be defined from so many views and opinion. Therefore, to give an

exhaustive definition of a computer, we look at three (3) descriptions.

1. A computer is a set of interrelated and interactive devices which use electronic components to

perform a predefined operation with accuracy.

2. A computer is also a collection of electronic components or hardware that has a set of electronic

instructions called software, and can perform enormous calculations.

3. A computer is also an electronic device capable of computing, processing, manipulation and storage

of data.

Brief History of ComputersComputers have been around for almost 5000 years. One of the earliest computers was the abacus – a series of

beads arranged on metal rods. Shown below is the picture of an early abacus computer.

Fig . 1. An early Abacus Computer

Computer history and development would not be absolute without mentioning Charles Babbage. He is widely

regarded as the father of computer, and is widely credited with being the first to invent a mechanical computer

that led to so many complex designs found today. He invented what is today referred to as the analytical engine,

designed in 1837. This was one of the earliest forms of computer. A picture of the analytical engine is shown

below.



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Fig. 2. The Analytical engine

Computer history and development can be subdivided into five (5) distinct generations.

1. The First Generation Computers 1944-1959

This generation of computers was characterized with the vacuum tube technology. They used vacuum

tubes as memory devices, they were bulky, expensive, dissipated a lot of heat, took a lot of space, used the

assembly language for programming and were very slow (they could take days to solve a problem a modern

computer would solve in 5 micro seconds). They also needed a special coding system. Such computersinclude:

i. The ENIAC (Electronic Numerical Integrator and Calculator): this was the very first electronic general

purpose computer capable of being programmed over and over again to solve different computing

problems.

ii. EDSAC (Electronic Delay Storage Automatic Computer)

iii. UNIVAC I & II (Universal Automatic Computer)

iv. IBM 604, 650, 701, 702v. SSEC (Selective Sequence Electronic Calculator)

It was also during this generation that the first version of FORTRAN (Formula Translator) was published by

IBM in 1954. FOTRAN is the earliest high-level computer programming language for general purpose.



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Fig. 3. A First Generation Computer

2. The second generation computers (1959-1964)

The new transistor technology was the distinguishing characteristic of this generation of computers. It

marked the start of this generation. This new technology was discovered at the Bells telephone laboratory and

was largely used in the electronic world, but was introduced into the manufacture of computers in 1959. These

transistors began replacing the vacuum tubes leading to a reduction in size, increased reliability, reduction in

power requirements and lower cost of manufacture of computers. This generation of computers started showing

the features of modern day computers such as, disk storage, printer, and operating systems. Also, this generation

replaced machine language with assembly language and high-level programming languages like COBOL

(Common Business Oriented Language). Though the assembly language was tedious, it was easy compared to

writing binary codes. A setback of this generation of computers was the heat dissipated by the transistors, which

caused damage to sensitive parts of the computer. Second generation computers include:

i. IBM 7030

ii. IBM 7070

iii. IBM 7090, 7094

iv. Boroughs 200 series

v. UNIVAC III

vi. Honeywell 800



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Fig. 4. IBM 7094 (a second generation computer)

Third Generation Computers (1964-1971)

It was the development of the integrated circuit (IC) technology that ushered in the third generation of

computers. This was the beginning of the revolution of computer technology itself. The IC technology

combined electronic components in form of a circuit onto a small silicon wafer or chip made from quartz. This

technology started out from small scale integration (SSI) which contained about twenty (20) transistors and

diodes on a single chip, to large scale integration (LSI) of over ten thousand (10, 000) transistors and diodes ona single chip. This led to the manufacture of better, faster, more reliable, cheap, and extremely small sized

computers compared to previous ones. They were extremely faster than those of earlier generations, and

operating systems started allowing other applications to run on them. Third generation computers include:

i. IBM 31360-31370 series

ii. CDC (Control Data Corporation)6600, 7600

iii. Boroughs B5000

iv. PDP II (Personal Data Processor) seriesv. UNIVAC 1107



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Fig. 5. A third generation Apple computer Fig. 6. An IC Chip (Consider revising)

Fourth Generation Computers (1971-Present)

This generation of computers was characterized by Very Large Scale Integration (VLSI), and Ultra Large

Scale Integration (ULSI) which ensured that millions of electronic components could fit into a very small

silicon chip. This reduced the cost of manufacturing and cost of buying a computer. VLSICs had between 5,

000 and 50, 000 gates (Combination of transistors and Diodes) upon which microprocessors were built. This

technology resulted in further reduction of the size of IC chips that led to the huge reduction in size of

computers compared to earlier versions, very powerful, and very fast in such a way that its predecessors were

considered ordinary. The Intel 4004 chip, developed in 1971 took the IC one step further by combining all the

components of a computer (The Central Processing Unit, memory, input and output controls) onto a single tiny

chip. This generation also ushered in new application software such as word processing packages, graphics,

games, multimedia, etc. year by year, computer sizes kept reducing in size, and increasing availability for home

and office use.

Examples of fourth generation computers include:

i. Altair 8800 (1975)

ii. Apple II (1976)

iii. Lisa (1983)

iv. Apple Macintosh (1984)

v. All computers manufactured today.



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Fifth Generation Computers (Present and Beyond)

This is the era of artificial intelligence (AI). Fifth generation computers are still at the developmental stage

of design. They are only in the minds of research scientist. Though a lot of research has gone into this

generation of computers, testing is still being carried out in laboratories. These computers will work under the

influence of AI, i.e. such computers would be able to take instructions in audio-visual forms, and perform

instructions based on this, learn, and being capable of self-organization. Many of the operations which require

low human intelligence would be performed by such computers. Such operations include, opening a door,

responding to a knock on the door, running errands, walking, and carrying load from one point to another, etc.

They are also characterized by super large scale integration (SLSI), parallel processing, pattern recognition, etc.

they possess magnificent speed, and processing power.

Fig. 7. A robot working with a fifth generation computer



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BASICS OF COMPUTING

Switching on a Computer

A computer is usually switched on by pressing or sliding the power button or mechanism depending

(assuming a fresh startup). The location of the power button varies from system to system, but they all look the

same. Below are pictures of how a power button looks like in different colours and forms:

Fig. 2.1. Various forms of power button

The moment the button is punched the computer starts up (in some cases one may have to hold the button for

about three seconds).

Components of a Computer

Computers have two (2) main components viz.

1. Hardware

2. Software

HARDWARE

This is a collective name for all the parts or components physical to the computer (internal or external). They

can be touched, or felt. It includes the computer processor, memory, monitor, keyboard, mouse, and all

peripherals connected to the system unit.

Internal Hardware

These are components located inside the system i.e. they can‟t be seen first sight except if the system unit is

opened up during routine checks and so on. These include but not limited to the following:

i. The CPU (Central Processing Unit): This is the main physical component of a computer. It does all

the calculations, logical operation, and controls all the components on the system board (Motherboard).

It is the main microchip in the computer that assigns functions to other parts of the system.



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ii. Memory: The memory can be quite confusing at times, but it is usually one of the easiest pieces of

hardware to add to your computer. It is very common to confuse the chip memory with disk storage

which is the external memory. But our main focus is the chip memory which is an area that maintains

information for instant retrieval and processing, as distinct from the disk storage. The main memory are

RAM (Random Access Memory) and ROM (Read only Memory).

RAM: This is the memory that the computer uses to temporarily store the information as it is

being processed. The more the information a computer would process, the more the RAM the

computer would need. RAM memory chips come in different sizes and speed, and can usually be

expanded using the free expansion slots. RAM is usually referred to as a volatile memory

because the information stored in it disappears as soon as power is cut off or power is lost. Hard

drives and flash drives on the other hand, contain non-volatile memory which is like paper – ca

be destroyed or erased, but when properly taken care of can last forever.

ROM (Read only Memory): This is another type of storage medium widely used in electronicdevices for permanently storing information. It is a non-volatile memory i.e. it retains its

information even after power is lost. Data stored on a ROM cannot be modified. Although

modern technology has made that possible, though with difficulty compared to reading data from

it. The ROM in computers usually contains the Firmware (Specific instructions from the

manufacturers in reference to a specific hardware that cannot be changed). ROM is also used for

applications on various processors

Hard Disk Drive (HDD): As explained earlier, this is the external storage device in the computer.

Data to be stored permanently are stored in this device (though one can choose to erase it). It

retains data even after the power is removed. Sizes of hard drives these days are usually

measured in GB (Gigabyte). Most hard drives contain at least one motor inside which determines

the speed, though other factors contribute to the effective speed of a hard drive. The speed is

measured in RPM (rotations per minute). Most HDD today have a speed of 7200 RPM, with

4200 RPM models used in laptops, and 10000 RPM HDDs generally seen only in gaming and

other high performance computers due to their cost, and required high speed. Today we have

HDDs of sizes in Terabytes (1000 GB), and soon to be available Petabytes (1000 TB), and

Exabyte (1000 PB).



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Fig. 2.2. Section of an opened hard disk drive (HDD)

Memory Conversion Units

This is a way of measuring or quantifying memory allocations and sizes. Although, most external storage

devices are measured in GB, the can be effectively converted to other units for varying purposes. The least unit

of memory measurement in a computer is the bits (coined form two words, Bi nary, and digi ts ). The conversion

units are detailed below.

8 bits = 1 byte

1024 byte = 1 Kilobyte (KB)

1024 KB = 1 Megabyte (MB)

1024 MB = 1 Gigabyte (GB)

1024 GB = 1 Terabyte (TB)

1024 TB = 1 Petabytes (PB)

1024 PB = 1 Exabyte (EB)

It is a very common and generally acceptable practice of approximating the 1024 to 1000. But as a matter of

fact, it is wrongly conceived.

External Hardware

These are the devices and components attached to the computer, but are external to the main casing that

houses the CPU, HDD, RAM, and other such equipment. They are basically devices that help humans

communicate effectively with the computer. The most important are the keyboard, and the mouse, others



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include but not limited to, printer, game console keypad, joystick, modem, external HDD, projector, etc. we

can classify external hardware into the following categories:

a) Input devices

b) Output devices

a) Input Devices

These are devices/components that provide raw data to the computer to process and take necessary actions.

They are also devices that pass on information to the computer in suitable form for processing. Examples are

scanner, keyboard, joystick, keypads, mouse, microphone, etc.

The following are the most basic input devices usually provided with a computer.

i. Keyboard : this is the main input device provided with the system unit. The keyboard is the most widely

used device for interacting with a computer. Operating system (OS) such as Microsoft Windows XP can

be operated with nothing but the keyboard. Keyboards vary in appearance, and shapes. The standard

keyboard is called the QWERTY keyboard (Coined from the first row of alphabetical characters),

pron ounced as “kwurtee” keyboard. The standard QWERTY keyboard has five main types of keys viz.

Function keys: These include keys F1 – F12. They are used in performing different tasks

depending on the software running on the system.

Numeric keys: this include numbers 0-9, basic arithmetic signs (+, -, *, /), and are used to enter

numeric data into the system.

Navigation keys or arrow keys: These are the four (directional) arrows for moving up, down,

left, and right on the computer.

Alphanumeric keys (Typewriter keys): these include characters for typing and inputting data into

the system.

Special computer keys: This include all non-printable character such as, CTRL key, FN key,

ALT key, SHIFT key, SYSTRQ key, PRTSC, BREAK, PAUSE, ESC. These keys are usually

not found on a typical typewriter.

Others keys include the status indicator keys such as, CAPS LOCK, NUM LOCK, SCROLL LOCK, etc. these

keys toggle their respective modes ON or OFF each time they are pressed. When they are ON, an indicator light

is ON, and vice versa.



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Another type of keyboard is the Dvorak keyboard which is not well accepted around the world. The QWERTY

keyboard was preferred since it‟s the same as that which typewriters used, and also because of the rarity of

form, despite the Dvorak being more easy to use. Till date, Dvorak layout has not been able to replace the

QWERTY layout.

Fig. 2.3. A standard QWERTY keyboard showing the different keys and their locations

i. Mouse : This is also an input device primarily used by physically moving the device during which a

pointed arrow or cursor moves with the corresponding direction on the surface of the screen. Secondly,

the device is used in “clicking” or selecting after the mouse is used in moving the cursor over the surface

of an object or icon on which an operation is to be performed. Mice usually have at least one (1) button

on them.

One button mice : The Apple mouse is the only mouse known to most people which use a single

button. This button is usually activated by pushing on the front of the mouse, or pushing the

entire mouse down. This has the benefit of being a simpler interface, and arguably more

attractive with a better design, but suffers from the fact that it is slightly more of a hassle to use,

with the traditional "right click" needs being changed to pressing a "control" or "ctrl" key on the

keyboard while pressing the main button. These are only used with Macintosh OS, such as MacOS X. (Consider revision).



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Fig. 2.4. A one button mouse (Apple‟s Mighty mouse)

Two button mice: This is the second most common design known to most people. It has one

button on the left (for the index finger), and one on the right (for the middle finger). When a two

button mouse is combined with the keyboard, they can perform virtually all the tasks on a

computer system.

Fig. 2.5. Standard two button mouse



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Three button mice: These are no different from a two button mouse, except that, there is a third

button in between the left and right click buttons, called a scroll wheel. A mouse technically has

three buttons, this may be confusing to users as the centre click button is also the scroll key.

When a user wants to scroll through a document, instead of using the arrow keys, the middle

button is rolled toward the direction of scroll, up or down. Now, the middle button can also be

pressed down, to scroll through documents while moving the mouse towards the direction of

scroll, up or down (while the button is still pressed). Also, depending on the program running,

clicking the middle button may perform operations specific to a program.

Fig. 2.6. Standard three button mouse

Four button mice: These are specialized mice seen only in gaming and multimedia applications.These extra buttons usually do not have a predefined function as other buttons, but are usually

assigned tasks to perform by the user.

Fig. 2.7. A four button mouse (Consider changing picture)



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Usually, all the above mice can either be laser/optical controlled or track ball controlled, called ball mice.

Laser/optical mice have already phased out ball mice, as they are more accurate, no difficulties in using them,

and they can be used on more surfaces, but the ball mice are cheaper. On a final note, when buying a mouse,

consider the size of your hand. If it feels awkward, too small, big, long short, change it and get a better one.

a) Output devices

These are devices/components used to obtain, extract information from the computer. They are also used to

provide hard or soft copies of the processed information. Examples are monitor, printer, speakers, projector, etc.

The most basic of these required is the monitor.

Monitor: This is the most important output device without which a computer cannot be complete. It displays

videos, images, and documents processed by a computer.

Fig. 2.8. Picture of a Monitor

SOFTWARE

This is a very important component of the computer. It is the component that cannot be seen with the

physical eyes. By definition, software is set of computer instructions or machine-readable instructions that

direct the processor to perform specific tasks . Without a software, all the hardware on a computer are literally

“dummies ” as they cannot perform any task without instructions on how to perform assigned tasks. Software

provides the detailed and complete instructions required for the hardware to perform tasks. Software can be

thought of as the variable component of a computer system, i.e. it can change. While the hardware can be

thought of as the invariable component as it cannot change. The whole computer in itself is also a hardware,

which also requires its own software for operations. This is usually the operating system.

Classification of Software

There are two (2) major classes of software viz. system software, and application software. The third being

firmware is not widely accepted as a type of software by itself. Some IT (information technology) supporters

classify it under system software, some under application software.

a. System software or utility software: System software is a program that coordinates and controls the

activities and functions of all the hardware, numerous other programs, and act as an interface with

application programs. They perform functions such as, efficient use of resources (CPU, I/O, and



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memory), file editing, queuing operations, etc. System software includes compilers and language

translators, operating systems (OS) which help various programs interact with the hardware, managing

and execution of user programs, coordinates multitasking operations, management and access of

memory and storage, time-sharing operations, etc. examples of operating systems are:

Microsoft Windows

Linux

Macintosh Mac OS

Assembler and compiler software

b. Application software: These are programs that perform specific tasks for users. They are designed and

tailored to suit specific needs of users in business, personal, research, computation, etc. They assist users

in increasing productivity in business, support household activities, education, facilitate effective

communication, assist with multimedia and graphics project, etc. Classes of application software include

but not limited to: Business/productivity software such as, word processing programs (Microsoft word, Latex,

Notepad, etc.), spreadsheet applications (MS-Excel, Lotus 123, Peachtree, etc.), data base

management programs (MS-Access), etc.

Graphics design/Multimedia: These include Corel draw, Desktop publisher, Adobe Photoshop,

Dreamweaver, fireworks, CAD/CAM etc.

Antivirus programs: this will be discussed in details later. Examples include, Norton, Kaspersky,

Quick heal, NOD 32, Avira, AVG, etc.

And the last, industry specific software.

c. Firmware: This is not widely accepted as a class of software, as it has both characteristics of hardware

and software. By definition, it is a combination of memory and program code meant for the smooth

operation of a device. Typical examples of devices containing firmware are embedded systems such as,

remotes (for TVs, DVDs, and associated devices), cameras, phone, traffic lights, computer and computer

peripherals (Printers, Web cams, Flash drives, game keypads, mouse, etc.), etc. The firmware provides a

control program for the device. Such program is usually held or stored in the ROM. Another name for

firmware is device driver software.

Steps to Create a New Folder

Locate where you want the folder to be

Right click on a free space in the location

Point at „New‟



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Select folder

Name the folder (Rules of naming documents must be adhered to ).

Steps to Delete a File or Folder

There are two (2) types of delete viz. temporary delete (which moves files and documents to recycle bin), and

permanent delete (which deletes file, folder or document permanently from the computer) .

Temporary Delete

Select the file, folder or document to delete by clicking on them

Press the „ DEL ‟ or „DELETE ‟ key

Permanent Delete

Select the file, folder or document to delete

Press SHIFT+DELETE or SHIFT+DEL (Done by holding down the shift key, and pressing the delete

key)

Quitting a Program

To quit or close a running program, the following steps are required:

Click the close button at the extreme top- right corner of the window (usually has an „X‟ symbol on it)

Or, click file on the menu bar of the application or program, click on „Exit‟ on the drop down list

Switching off a Computer

A computer cannot, and must not be switched off the same way it was switched on, as this may interrupt several

important processes, temporary loss of data, computer mis operation, might make the computer behave

haphazardly and sometimes cause irrecoverable loss of data. The following steps must be taken to switch off or

“shut down” as it is commonly known:

For Windows XP users

i. Click on the “START” button.

ii. Click on “Turn off Computer”, after which a box appears on screen.



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Start Button Turn off Computer

Fig. 3.2 . Diagram showing steps 1 of how to “shut down a computer”

iii. Click on “Turn off ”.

Fig. 3.3. Diagram showing step 2 of how to “shut down” a computer .



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For Windows Vista, 7, and 8 users

i. Click on the “ START ” button (located at the extreme bottom left)

ii. Click “ SHUT DOWN ”

The steps are shown graphically below:

Start button Shutdown button

Fig. 3.3 . Picture showing the shutdown procedures for Windows 7 users



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BASIC COMPUTER PROGRAMMING CONCEPTS

INTRODUCTION

Computer programming (sometimes known as coding) is the process of designing, writing, testing, debugging,

and maintaining source code of computer programs. It is a software design process. This source code is usually

written in one or more programming language, and then interpreted or translated into machine language by an

interface for the computer to execute the required tasks.

Programming is a way of creating a set of instructions for a computer to execute. Such instructions might be

solution to a problem, therefore, programming is an art of problem solving. The process of writing source codes

requires a lot of experience in different subject areas, including the domain of the application in question.

The earliest computer programming language was the machine language. This is the natural language of the

computer, and it consists of binary digits called bits (0, 1). This language was redundant, repetitive, tedious,

frustrating, very unreliable, and largely inefficient. Then the assembly language which is a low level language

(LLL) was developed to address this issue. Assembly language used human readable text mnemonics to

represent variables, such as but an assembler (some kind of interpreter) was required as an interface to translate

assembly language statements into machine language which the computer understood. Examples of assembly

language statements are; LCALL (Local call), BEGIN, START, MOV (move), JMP (jump), RET (return), CLR

(clear), SETB (set bit), etc. other languages after assembly language were classified under high level languages

(HLL).

Classification of Programming Languages

There are majorly two classes of programming language, with sub-classes, namely;

1. Low level languages (LLL): These are the earliest languages, and they are machine or architecture

dependent i.e. for instance, every machine has its own form of the language. Examples include machine

language, assembly language.

2. High level language (HLL): This can be further classified into:

i.

Object Oriented Languages: These languages allow users to create and define their own functions asrequired. Examples are C++ (pronounced Cee plus plus), JAVA, VB.net (VBASIC.net), C#

(Pronounced Cee sharp), Python, etc.

ii. Procedural Languages or Procedure oriented languages: Most HLLs fall under this category, and are

known for their step by step method (or procedure method) of solving problems. With these kinds of

languages, one or more related blocks of statement that perform the same function are grouped together



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under a common procedure of module. Examples are BASIC, C, FORTRAN, COBOL, PASCAL, Ada,

VBASIC (Visual BASIC), etc.

iii. Non-Procedural or Logic Languages: These programming languages do not follow a step-by-step

procedure in solving problems. All you need to do is specify what the program should do, rather than

outlining the steps to do it. Popular examples are, MySQL (My Structure Queried Language), PROLOG.

Programming Languages

Low Level Languages (LLL) High Level Languages (HLL)

E.g. Machine language, assembly language

Object Oriented Languages (OOL) Procedural Languages Non-Procedural languages

C++, Java, C# VBASIC, FORTRAN, BASIC, C, Ada, PASCAL MySQL

Fig. 3.1 . Classification tree for Programming languages

GUI

This is an acronym for Graphical User Interface, and is sometimes pronounced as “Gooee”. It is a pictorial

interface to a program. It is basically a user friendly environment, easy to learn, and easy to use environment

since it is based on what we already know. GUI makes a program easier to use by providing a neat appearance

with intuitive controls like push buttons, icons, sliders, menus, list boxes, and so forth. GUI usually has an

understandable and predictable manner in such a way that a user knows what to expect when he/she performsan action. It allows users to interact with electronic devices using images rather than text commands. GUI is

used in almost all electronic devices such as computers, hand-held devices, phones, and a host of industrial

equipment.



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HARDWARE BASICS

THE MOTHERBOARD

The motherboard is the main printed circuit board (PCB) of the computer. It refers to a PCB with expansion

capabilities. It is sometimes referred to as MB, Mobo, system board, or logic board. Everything on the computer

connects directly or indirectly to the motherboard; the peripheral devices, sound cards, video cards, optical

drives, etc. all connects to the motherboard. The name “mother” was coined because it is the mother of all

components attached to it. It feeds them with information, provides a path for all the components to

communicate with each other, and supplies them with power supply to function. The motherboard serves one

major function; to act as a central terminal where everything else connects to it. It also holds the computer‟s

microprocessor chip, and let everything else connect to it.

There are various configurations, designs, and architectures (Layout of design) of motherboards based on

different needs and budget. Many computer stalwarts and enthusiasts favour one kind of motherboard over

another, and choose based on the hardware it can support. Motherboards have a huge effect on the capabilities

of a computer, as such, care attention must be taken when purchasing a new motherboard, or replacing an old

one. Desktop and laptop motherboards vary in so many instances. For example, when a component on a desktop

PC motherboard is faulty, such component can be replaced if the fault has not spread to other components. But

a faulty component on a laptop computer would almost result to complete replacement of the whole

motherboard. Also, laptop motherboards are more compact, highly integrated, and much smaller than desktop

PCs. With laptop MBs everything is soldered onto the board with sockets with which to connect devices. Belowis a picture of a generic motherboard.



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Fig. 4.1. A generic motherboard

Fig. 4.2. A typical Intel Motherboard

BIOS (Basic Input Output System)

BIOS is an acronym for Basic Input Output System. It is special software called firmware that interfaces the

major hardware components of the computer. The BIOS is virtually on every computer available, and it makes

sure all other chips, hard drives, ports, and CPU (Central Processing Unit) function together. The firmware for

BIOS has a number of different roles but the most important is the loading of the OS into the memory at startup.

The first instruction the microprocessor executes comes from the BIOS chip. The BIOS is also responsible for

checking and activating other BIOS chips (Hardware specific BIOS) installed on the computer e.g. graphics

card often have their own in-built BIOS chip.



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VIRUSES and ANTIVIRUS

VIRUS

Viruses are small executable software programs that can replicate themselves, and are designed to spread

from one computer to another, disrupt, and interfere with computer operations. Virus is most commonly and

wrongly used to refer to all malware (Malicious software). Malware include all computer viruses, worms,

Trojan horses, key loggers, backdoors, spyware, etc. all viruses are malware, but not all malware are viruses.

Malware such as spyware, adware, etc., do not have reproductive capabilities.

Trojan horses and worms are sometimes confused with viruses but they are technically different. A worm

can exploit security weaknesses to spread itself automatically, while a Trojan horse is a program that appears

harmless but hides malicious functions (Got this name from the movie “Achilles” where a wooden horse called

Trojan horse was used). Most malwares seen and observed these days are usually Trojans or worms rather than

viruses. Some viruses do nothing beyond replicate themselves, taking up useful space in the memory, thereby

reducing the system speed and overall performance. Viruses are created by programmers for pleasure or for

malicious intentions like data mining, interfering and disrupting proper operation of a computer system, causing

panic in the users mind, and spread are through telecommunication networks, shared flash drives or storage

media, internet, etc.

Some viruses require a host program to activate them. Whenever such program is loaded onto the memory,

they are activated, installed, and they begin to replicate themselves until the program is closed.

Types of Virus

1. Parasitic Virus: this kind of virus attaches itself to other programs, and is activated when the host

program is loaded to the memory, they starts execution and reproduction, attaching itself to more

programs thereby increasing its chance of being activated. This process continues on and on until the

system crashes if nothing is done to eliminate the threat.

2. Boot Virus: This is designed to enter the boot sector of a hard drive. Once there, they replace the boot

sector with their own self, and hides itself elsewhere on the drive with a copy of the first in the sector.As the computer is started from power off, the virus loads, installs itself, hides, and then loads the host

program. This kind of virus is the most dangerous, as they directly attack the operating system, not just a

program.



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Names of viruses may not be mentioned in this text as this will led to ambiguity and confusion. This is because,

as a new virus appears and developers begin the rush to identify it, understand it, give a name to it based on its

behavior, and mode of operation, as well as develop counter-measure against its propagation. These developers

attach a name to such virus independently. By the time the virus is properly identified, many names already

denote the same virus. This calls for confusion and ambiguity, and for this reason, examples of virus would not

be mentioned as they may all mean the same thing.

ANTI-VIRUS

This is also a software program used to prevent, detect, remove malware of all types, provide security for

computers, and takes action to disarm or remove malicious software. A lot of techniques and strategies are used

in detection. Such include signature based detection, where the antivirus searches for known patterns of data

within executable codes. Also, heuristic approach can be used with a new malware, i.e. trial by error, whereby a

new virus is a variant of an existing one with known signatures. Some antivirus tries running a file or

executable code to see if it performs malicious function.

There is no antivirus software that can perfectly detect all possible viruses. But the best offer as much as

99.6% detection rate with the least offering 88.1%. Most antivirus offer real-time protection, resident shield,

auto-protect, etc. To help prevent most current viruses, users must update their anti-virus software regularly.

Most antivirus can be set to automatically update regularly. Examples of known antivirus software are, McAfee,

Bit defender, Norton, AVG, Avira, Nod32, Avast, etc.

Draw Backs of Antivirus

i. Antiviruses impair a computer‟s ability to function properly by taking memory space, and slowing down

the system when running.

ii. Antiviruses generate random errors that user may not understand, leading them to take an incorrect

decision.

iii. Some antiviruses send messages that constantly interrupt and disrupt the user when they are performing

tasks that require maximum attention.

Some antivirus might identify a non-malicious and sometimes very important documents (such as operating

system binary files) as a virus which may be quarantined or deleted immediately without approval from the

user, rendering some programs or even the operating system itself unusable.



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PIONEERS IN COMPUTER DEVELOPMENT

1. Blaise Pascal (1623-1662): He was a French mathematician, physicist, inventor, writer, and a Christian

philosopher. He designed the first mechanical calculator based on gears. It performed addition and

subtraction.

2. Wilhelm Von Leibnitz (1646-1716): He was a German mathematician, and he built the first calculator to

do multiplication and division.

3. Charles Babbage (1791- 1871): He was a British inventor who designed an “analytical engine”

incorporating the ideas of memory and card input/output for data instructions. The current technology as

at then did not permit the completion of the machine. Babbage was largely remembered because of the

works of Ada Augusta on the analytical engine, who is arguably the first computer programmer.

4. Williams S. Burroughs (1857-1898): Introduced the first commercially successful mechanical adding

machine which sold a million by 1926.

5. Herman Hollerith (1860-1929): He was an American statistician and inventor. He developed an

electromechanical punch card tabulator to tabulate data for the 1890 US census. He later formed the

tabulating machine company International Business Machine (IBM). IBM is still one of the largest

computer companies in the world. They actually started the business of commercially available

computer.

6. Howard H. Aiken (1900-1973): He was a Harvard professor who built the Harvard mark I in 1944. It

was based on relays (which are electromagnetic) as opposed to the use of gears (which is mechanical).

7.

Eckert and Mauchly: They designed and built the ENIAC in 1946 for military applications. It was basedon vacuum tubes which is completely electronic.

8. John V. Atanasoff (1903-1995): He was an American physicist and inventor best known for the first

digital computer. He built a specialized computer in 1941 and was visited by Mauchly before the

construction of ENIAC. He sued Mauchly in a case which was decided in his favour in 1974.

9. Von Neumann (1912-1954): He was a British mathematician who also made contributions to early

development of computing. He is credited with developing the Von Neumann architecture.



26

IMPORTANT WINDOWS OS KEYBOARD SHORTCUTS

A keyboard shortcut is a single key or combination of keyboard strokes (For combination shortcuts, all keys

must be punched in the order shown ALT+DEL is not the same as DEL+ALT) on a computer to invoke or call a

specific command in software. They allow for easy and fast navigation of the computer system, help with wrist

fatigue, and in some cases my save power consumption (where more keystrokes will consume more power).

Commonly used keyboards on WINDOWS OS and their description include, but not limited to the following;

HOME To go to the beginning of a page, folder, line, or sentence.

END To go to the end of a page, folder, line, or sentence

DELETE (DEL) To delete to recycle bin

F2 Rename a selected item

ESC To cancel the current task

F3 Search for a folder or file in the computer (excluding system folders and file like “Program File”)

BACKSPACE To view the folder one level up (or previous folder) in “My Computer” or windows

explorer

SHIFT+DEL To delete a selected item permanently from the computer without sending it to the

recycle bin

CTRL Used for selecting more than one item by holding down the key while selecting the items

CTRL+A Select all

CTRL+F4 Close the active document in programs that allow multiple documents to be open at the

same time

CTRL+ESC Display the start menu (this shortcut cannot replace the windows key in other shortcuts)

CTRL+C To copy

CTRL+X To cut

CTRL+V To paste

CTRL+Z To undo (the previous task performed) CTRL + +F To search for computers (On a network)

CTRL+SHIFT+ESC To open task manager

CTRL+SHIFT+N Creates a new folder in your current directory

ALT+ENTER View the properties of a selected item



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ALT+TAB Switch between running applications or items

ALT+F “File” menu drop down list (displays the contents of the file menu when running an

application)

ALT+E “Edit” menu drop down list (displays the contents of “edit” menu when running an

application)

ALT+F4 To quit or close a program

+M To minimize ALL the windows running, and show desktop

+D To display desktop

+E To open “My Computer”

+F Search for a file (same as F3)

+L To lock keyboard or desktop

+1, 2, 3, 4 … etc. To launch each program on the taskbar in the order they have been lined up

+HOME Minimizes all windows or application except the one running

+PAUSE To open system properties window

+ALT+1, 2, 3 …etc. to open the jump list for each program in the order they appear on the taskbar

+SHIFT+M Restore minimized windows

Displays start menu

*********** Take note that represents the windows key



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LIST OF IMPORTANT COMPUTER ABBREVIATIONS

A

ALU – Arithmetic Logic Unit

AMD – Advanced Micro Devices

ASCII – American Standard Code for Information Interchange

ATA – Advanced Technology Attachment

AMOLED – Active Matrix Organic Light Emitting Diode

B

BIOS – Basic Input Output System

C

CD – Compact Disc

CR-RW – Compact Disc Rewritable

CD-ROM – Compact Disk Read Only Memory

CMOS – Complementary Metal Oxide Semiconductor

CPU – Central Processing Unit

CAD – Computer Aided Design

CDMA – Code Division Multiple Access

D

DDR – Double Data Rate

DDR-SDRAM - Double Data Rate Synchronous Dynamic Random Access memory

DIMM – Dual Inline Memory Module

DPI – Dots per Inch

DVD – Digital Versatile Disc

DVD+RW – Digital Versatile Disc Rewritable



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E

EEPROM – Electrically Erasable Programmable Read Only Memory

EPROM – Erasable Programmable Read Only Memory

G

GB – Giga Byte

GHz – Giga Hertz

GIGO – Garbage in Garbage Out

GUI – Graphic User Interface

H

HDD – Hard Disk Drive

HDMI – High Definition Media Interface

HDTV – High Definition Television

Hi-Fi – High Fidelity

HTTP – Hyper Text Transfer Protocol

I

IBM – International Business Computer

IC – Integrated Circuit

IDE – Integrated Drive Electronics

ISA – Industry Standard Architecture

I/O – Input Output

IP – Internet Protocol

J

JPEG – Joint Picture Experts group



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K KBps – Kilobytes per Second

Kbps – Kilobits per second

L

LAN – Local Area Network

LCD – Liquid Crystal Display

LED – Light Emitting Diode

M

MB – Mother Board

MBps – Megabytes per second

Mbps – Megabits per seconds

MIPS – Million Instructions per second

MODEM – MOdulate DEModulate

MPEG – Moving Picture Expert Group

O

OCR – Optical Character Recognition

OMR – Optical Mark Recognition

P

PC – Personal Computer

PCB – Printed Circuit Board

PCI – Peripheral Component Interconnect

PDA – Personal Digital Assistant

PGA – Portable Graphics Array

PnP – Plug „n‟ Play



PDF – Portable Document Format

PHP – Hyper Text Preprocessor

PNG – Portable Network Graphics

R

RAM – Random Access Memory

ROM – Read Only Memory

RPM – Revolutions per Minute

T

TB – Terabytes

TFT – Thin Film Transistor

U

USB – Universal Serial Bus

V VGA – Video Graphics Array

VDU – Visual Display Unit

W

WAN – Wide Area Network

WYSIWYG – What You See is What You Get (Pronounced Wizeewig)

Wi-Fi – Wireless Fidelity

WWW – World Wide Web

Documents

Introduction to Computers and Computing