introduction to information and communication techonology

Computers should have alarm systems to guard them from any attacks such as viruses and data corruption. The alarm system is the security measures that we take to ensure its safety.

DATA PROTECTION
We need to protect the data in the computer as it may somehow get lost or corrupted due to some viruses or mishap like fire, flood, lightning, machine failures and even human errors.

There are a few ways to protect the information namely:
• make backup files
• detect the virus and clean the computer
• warn others on virus attacks

1) BACKUP FILES
Users can do backups of file systems by:

 keeping the duplicated files in external storage such as in the floppy disk and thumb drive
 do backup frequently

2) DETECT VIRUS AND DO CLEANUP
A computer virus is able to affect and infect the way the computer works. Viruses can be detected when we run an antivirus. We can also delete the infected files and documents.

3) WARN OTHERS ON VIRUS ATTACK
We can warn others on virus attacks or new viruses by sending e-mails to them.
DETECTING ILLEGAL ACCESS TO SYSTEMS
The computer system is able to detect any illegal access to the system by a user who does not have any authorisation. Basically, a corporation will simply use tcpwrappers and tripwire to detect any illegal access to their system. User's access will be reviewed periodically by computer operations. On going internal audits will be made to ensure detection of violations of security and unauthorised modifications to software and data .

TCPWRAPPERS

Tcpwrappers stop the attempted connection


examines its configuration files


will decide whether to accept or reject the request.

Tcpwrappers will control access at the application level, rather than at the socket level like iptables and ipchains. The system will run tcpwrappers to log access to ftp, tftp, rch, rlogin, rexec and telnet.

TRIPWIRE
Tripwire will detect and report on any changes in the thousands of strategic system files.
The system will run tripwire to determine if system files have changed.

PREVENTING ILLEGAL ACCESS TO SYSTEMS
Ways to prevent illegal access to systems:
1. Run anlpassword to make password cracking difficult.
2. Run tcpwrappers to check if the name for an ip address can be provided by DNC
3. Use a callback system to prevent unauthorised use of stolen passwords.

PREVENTING ILLEGAL ROOT ACCESS

Sudo stands for (Superuser do) and is a program in Unix, Linux and similar operating systems such as Mac OS X that allows users to run programs in the form of another user (normally in the form of the system's superuser).

Sudo allows a permitted user to execute a command as the superuser or another user, as specified in the sudoers file.

PATCH
Patch supplies small updates to software, provided that the source code is available.
Patch is a name of an UNIX utility. It applies a script generated by the different program to a set of files that allows changes from one file to be directly applied to another file.

Resources are not enough to patch all security holes that we hear about through the bugtraq list.

L19: RELATIONSHIP BETWEEN SECURITY THREATS AND SECURITY MEASURES

SECURITY THREADS

Security threats may come from in many forms. For example, when someone is invading your account information from a trusted bank, this act is considered as a security threat.

Security measures can be used to prevent this invader from getting the account information. For example, the bank can use a firewall to prevent
unauthorised access to its database.

MALICIOUS CODE THREATS VS. ANTIVIRUS AND ANTI-SPYWARE
Security threats include virus, Trojan horse, logic bomb, trapdoor and backdoor, and worm.

Antivirus and anti-spyware can be used to protect the computer from the threats by:
 limiting connectivity
 allowing only authorised media for loading data and software
 enforcing mandatory access controls
 blocking the virus from the computer program

HACKING VS. FIREWALL
Hacking is an unauthorised access to the computer system done by a hacker. We can use firewall or cryptography to prevent the hacker from accessing our computers.

A firewall permits limited access to unauthorised users or any activities from the network environment. Cryptography is a process of hiding information by changing the actual information into different representation, for example, an APA can be written as 7&*.


NATURAL DISASTER VS. DATA BACKUP
The natural and environmental disasters may include:
• flood
• fire
• earthquakes
• storms
• tornados

The backup system is needed to backup all data and applications in the computer. With the backup system, data can be recovered in case of an emergency.

THEFT VS. HUMAN ASPECTS
Computer theft can be of two kinds:
 can be used to steal money, goods, information and computer resources
 the actual stealing of computers, especially notebooks and PDAs

Measures that can be taken to prevent theft:
 prevent access by using locks, smart-card or password
 prevent portability by restricting the hardware from being moved
 detect and guard all exits and record any hardware transported

BE SUPSPICIOUS OF ALL RESULTS

There are many instances where non-programmers develop applications which are not built with proper understanding of software engineering practices. Data produced by such applications may not be correct and may risk corrupting data received from other sources that are not compatible with the application.

L18: SECURITY MEASURES

Security measures mean the precautionary measures taken toward possible danger or damage. There are 6 type of security measures.

1) DATA BACKUP
Data Backup is a program of file duplication. Backups of data applications are necessary so that they can be recovered in case of an emergency.

2) CRYPTOGRAPHY
Cryptography is a process of hiding information by altering the actual information into different representation, for example, an APA can be written as I? X.

Almost all cryptosystems depend on a key such as a password like the numbers or a phrase that can be used to encrypt or decrypt a message.

The traditional type of cryptosystem used on a computer network is called a symmetric secret key system.

3) ANTIVIRUS
An antivirus program protects a computer against viruses by identifying and removing any computer viruses found in the computer memory, on storage media or incoming e-mail files. An antivirus program scans for programs that attempt to modify the boot program, the operating system and other programs that normally are read from but not modified.

IDENTIFYING VIRUS
Two technique are used to identify the virus.

If an antivirus program identifies an infected file, it attempts to remove its virus, worm or Trojan horse. If the antivirus program cannot remove the infection, it often quarantines the infected file. Quarantine is a separate area of a hard disk that holds the infected file until the infection can be removed. This step ensures other files will not become infected. Patents for inventions Utility, design or plant patents that protect inventions and improvements to existing inventions

4) ANTI-SPYWARE
Spyware is a program placed on a computer without the user’s knowledge. It secretly collects information about the user.

The spyware program communicates information to the outside source.

An anti-spyware application program sometime called tracking software or a spybot is used to remove spyware.

Among of the popular anti-spyware programs are:
• Spybot Search and Destroy
• Ad-aware
• Spyware Blaster

5) FIREWALL
Firewall is a piece of hardware or software which functions in a networked environment to prevent some communications forbidden by the security policy.

Firewall implement a security policy. It might permit limited access from in or outside the network perimeters or from certain user or for certain activities.



6) HUMAN ASPECTS OF SECURITY MEASURES
Human aspects refer to the user and also the intruder of a computer system.
It is one of the hardest aspects to give protection to.

The most common problem is the lack of achieving a good information security procedure

L17: INTRODUCTION COMPUTER THREATS

The computer is a great tool to store important information. In certain cases, the information is very vital that losing it will harm the computer system.

Computer threats can come from many ways either from human or natural disasters. For example, when someone is stealing your account information from a trusted bank, this threat is considered as a human threat. However, when your computer is soaked in heavy rain, then that is a natural disaster threat.

MALICIOUS CODE
Malicious code is also known as a rogue program. It is a threat to computing assets by causing undesired effects in the programmer’s part. The effect is caused by an agent, with the intention to cause damage.

The agent for malicious code is the writer of the code, or any person who causes its distribution. There are various kinds of malicious code. They include virus, Trojan horse, logic door, trapdoor and backdoor, worm and many others.
a) VIRUS
• a program that can pass on the malicious code to other programs by modifying them
• attaches itself to the program, usually files with .doc, .xls and .exe extensions
• destroys or co-exists with the program
• can overtake the entire computing system and spread to other systems

b) TROJAN HORSE
• a program which can perform useful and unexpected action
• must be installed by users or intruders before it can affect the system’s assets
• an example of a Trojan horse is the login script that requests for users’ login ID and password
• the information is then used for malicious purposes

c) LOGIC BOMB
• logic bomb is a malicious code that goes off when a specific condition occurs.
• an example of a logic bomb is the time bomb
• it goes off and causes threats at a specified time or date

e) TRAPDOOR OR BACKDOOR
• a feature in a program that allows someone to access the program with special privileges

f) WORM
• a program that copies and spreads itself through a network

Primary Differences Between Worms And viruses

Worm Virus
Operates through the network Spreads through any medium
Spreads copies of itself as a standalone program Spreads copies of itself as a program that attaches to other
programs
HACKER
Hacking is a source of threat to security in computer. It is defined as unauthorised access to the computer system by a hacker. Hackers are persons who learn about the computer system in detail. They write program referred to as hacks. Hackers may use a modem or cable to hack the targeted computers.

NATURAL AND ENVIRONMENTAL THREATS
Computers are also threatened by natural or environmental disaster. Be it at home, stores, offices and also automobiles.Examples of natural and environmental disasters:
 Flood
 Fire
 Earthquakes, storms and tornados
 Excessive Heat
 Inadequate Power Supply

THEFT
Two types of computer theft:
1) Computer is used to steal money, goods, information and resources.
2) Stealing of computer, especially notebook and PDAs.

Three approaches to prevent theft:
1) prevent access by using locks, smart-card or password
2) prevent portability by restricting the hardware from being moved
3) detect and guard all exits and record any hardware transported

L16: COMPUTER SECURITY

DEFINITION OF COMPUTER SECURITY
Computer security means protecting our computer systems and the information they contain against unwanted access, damage, destruction or modification.

We need to protect our computer from any intruders such as hackers, crackers and script kiddie.

We do not want strangers to read our e-mail, use our computer to
attack other systems, send forged e-mail from our computer, or examine personal information stored on our computer such as financial statements.


TYPES OF COMPUTER SECURITY
Three types of computer security are:
a) hardware security
b) software security/data security
c) network security

a) HARDWARE SECURITY
Hardware security refers to security measures used to protect the hardware specifically the computer and its related documents.

The examples of security measures used to protect the hardware include PC-locks, keyboard-locks, smart cards and biometric devices.

b) SOFTWARE AND DATA SECURITY
Software and data security refers to the security measures used to protect the software and the loss of data files.

Examples of security measures used to protect the software are activation code and serial number.

c) NETWORK SECURITY
The transfer of data through network has become a common practice and the need to implement network security has become significant.

PERSONAL COMPUTER SECURITY CHECKLIST
In order to make sure our computers are secured, here are the computer
security checklist to follow.
 Do not eat, drink or smoke near the computer
 Do not place the computer near open windows or doors
 Do not subject the computer to extreme temperatures
 Clean the equipment regularly
 Place a cable lock on the computer
 Use a surge protector
 Store disks properly in a locked container
 Maintain backup copies of all files
 Stores copies of critical files off sites
 Scan a floppy disk before you open it
 Do not open any unknown email received

L15: COMPUTER CRIMES

COMPUTER CRIMES
A computer crime is defined as any criminal activity that is related to the use of computers. These activities include computer fraud, copyright infringement, computer theft and computer attack.

COMPUTER FRAUD
Computer fraud is defined as having an intention to take advantage over or causing loss to other people, mainly on monetary basis through the use of computers.

COPYRIGHT INFRINGEMENT
Copyright infringement is defined as a violation of the rights secured by a copyright. Copyright infringement involves illegal copy or reproduction of copyrights material by the black market group. The open commercial sale of pirated item is also illegal.

COMPUTER THEFT
Computer theft is defined as the unauthorised use of another person’s property with the intention to deny the owner the rightful possession of that property or its use.
Examples of computer theft include:
• transfer of payments to the wrong accounts
• tap into data transmission lines on database at no cost
• divert goods to the wrong destination

COMPUTER ATTACK
Computer attack may be defined as any activities taken to disrupt the equipment of computer systems, change processing control or corrupt stored data.
Computer attack can be in the forms of:
• physical attack that disrupt the computer facility or its transmission lines.
• an electronic attack that uses the power of electromagnetic energy to overload computer circuitry.
• a computer network attack that uses a malicious code to exploit a weakness in software, or in the computer security practices of a computer user

L14: CYBER LAW

What is Cyber Law?
Cyber law refers to any laws relating to protecting the Internet and other online communication technologies.

NEEDS FOR CYBER LAW
These concerns and issues clearly indicate why cyber laws are needed in online activities.

THE CYBER LAW ACTS IN MALAYSIA
The Malaysian Government has already passed several cyber laws to control and reduce the Internet abuse. These cyber laws include:
• Digital Signature Act 1997
• Computer Crimes Act 1997
• Telemedicine Act 1997
• Communications and Multimedia Act 1998

DIGITAL SIGNATURE ACT 1997
The Digital Signature Act 1997 secures electronic communications especially on the Internet. Digital Signature is an identity verification standard that uses encryption techniques to protect against e-mail forgery. The encrypted code consists of the user’s name and a hash of all the parts of the message.

COMPUTER CRIMES ACT 1997
The Computer Crimes Act 1997 gives protection against the misuses of computers and computer criminal activities such as unauthorised use of programmes, illegal transmission of data or messages over computers and hacking and cracking of computer systems and networks. By implementing the Computer Crimes Act 1997, users can protect their rights to privacy and build trust in the computer system. At the same time, the government can have control at a certain level over cyberspace to reduce cyber crime activities.

TELEMEDICINE ACT 1997
The Telemedicine Act 1997 ensures that only qualified medical practitioners can practice telemedicine and that their patient's rights and interests are protected.

These act provides the future development and delivery of healthcare in Malaysia.
COMMUNICATIONS AND MULTIMEDIA ACT 1998
The implementation of Communication and Telecommunication Act 1998 ensures that information is secure, the network is reliable and the service is affordable all over Malaysia.

This Act also ensures high level of user's confidence in the information and communication technology industry.

computer network and communication

10 INTRODUCTION

The purpose of a computer communications network is to allow moving information from one point to another inside the network. The information could be stored on a device, such as a personal computer in the network, it could be generated live outside the network, such as speech, or could be generated by a process on another piece of information, such as automatic sales transactions at the end of a business day. The device does not necessarily have to be a computer; it could be a hard disk, a camera or even a printer on the network. Due to a large variety of information to be moved, and due to the fact that each type of information has its own conditions for intelligibility, the computer network has evolved into a highly complex system. Specialized knowledge from many areas of science and engineering goes into the design of networks. It is practically impossible for a single area of science or engineering to be entirely responsible for the design of all the components. Therefore, a study of computer networks branches into many

areas as we go up from fundamentals to the advanced levels.

20 MOBILE COMPUTING

2.1 DEFINITION

Using a computing device while in transit. Mobile computing implies wireless
transmission, but wireless transmission does not necessarily imply mobile
computing. Fixed wireless applications use satellites, radio systems and lasers to
transmit between permanent objects such as buildings and towers.

2.2 SPECFIACTION, SERVICES AND FREQUENCIES OF MOBILE

COMPUTING

SPECIFICATIONUser Interface

•

S60 5th Edition

Display

•

3.5-inch TFT

•

16 Million Colors

•

mHD 16:9 Widescreen

•

640×360 pixels

Battery

•

Nokia Batter BP-4L

•

1500 mAh

Memory

•

Up to 48GB

•

32GB Internal Memory

•

16GB Micro SD Expansion Slot

Main Camera

•

Carl Zeiss Tessar Lens

•

5MP (2584 x 1938)

•

JPEG/EXIF (16.7 Million / 24-bit color)

•

Video Capture MPEG-4 VGA, 640×480 at 30fps

•

Aperture: F2.8

•

Focal Length: 5.4mm

•

Flash: Dual LED Camera

SERVICES

•

WLAN IEEE 802.11 b/g with UPnP support

•

Micro USB Connector

•

3.5 mm stereo headphone plug

•

TV-Out Support

•

Data transfer via Bluetooth 2.0

•

A-GPS

•

Internet surfing

FREQUENCIES

•

2G Network GSM 850 / 900 / 1800 / 1900

•

3G Network HSDPA 900 / 1900 / 2100

30 INTERNET TECHNOLOGY AND SERVICES

3.1 VoIP

Voice over Internet Protocol(VoIP) is a general term for a family of transmission

technologies for delivery of voice communications over IP (internet protocol)
networks such as the Internet or other packet-switched networks. Other terms
frequently encountered and synonymous with VoIP are IP telephony, Internet
telephony, voice over broadband (VoBB), broadband telephony, and broadband
phone.

Example of VoIP adapter setup

in residential network

3.2 BLOG

A blog is basically a type of
website, like a forum or a social
bookmarking site. As such it is
defined by the technical aspects
and features around it, and not
by the content published inside
it.

secure access to their organization's network. A virtual private networ

Generations of Computer

The history of computer development is often referred to in reference to the different generations of computing devices. A generation refers to the state of improvement in the product development process. This term is also used in the different advancements of new computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and computer memory has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.
Each generation of computers is characterized by major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices. Read about each generation and the developments that led to the current devices that we use today.

First Generation - 1940-1956: Vacuum Tubes

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. A magnetic drum,also referred to as drum, is a metal cylinder coated with magnetic iron-oxide material on which data and programs can be stored. Magnetic drums were once use das a primary storage device but have since been implemented as auxiliary storage devices.
The tracks on a magnetic drum are assigned to channels located around the circumference of the drum, forming adjacent circular bands that wind around the drum. A single drum can have up to 200 tracks. As the drum rotates at a speed of up to 3,000 rpm, the device's read/write heads deposit magnetized spots on the drum during the write operation and sense these spots during a read operation. This action is similar to that of a magnetic tape or disk drive.
They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Machine languages are the only languages understood by computers. While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers. Computer Programmers, therefore, use either high level programming languages or an assembly language programming. An assembly language contains the same instructions as a machine language, but the instructions and variables have names instead of being just numbers.
Programs written in  high level programming languages retranslated into assembly language or machine language by a compiler. Assembly language program retranslated into machine language by a program called an assembler (assembly language compiler).
Every CPU has its own unique machine language. Programs must be rewritten or recompiled, therefore, to run on different types of computers. Input was based onpunch card and paper tapes, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.
Acronym for Electronic Numerical Integrator And Computer, the world's first operational electronic digital computer, developed by Army Ordnance to compute World War II ballistic firing tables. The ENIAC, weighing 30 tons, using 200 kilowatts of electric power and consisting of 18,000 vacuum tubes,1,500 relays, and hundreds of thousands of resistors,capacitors, and inductors, was completed in 1945. In addition to ballistics, the ENIAC's field of application included weather prediction, atomic-energy calculations, cosmic-ray studies, thermal ignition,random-number studies, wind-tunnel design, and other scientific uses. The ENIAC soon became obsolete as the need arose for faster computing speeds.

Second Generation - 1956-1963: Transistors

Transistors replaced vacuum tubes and ushered in the second generation computer. Transistor is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit. Invented in 1947 at Bell Labs, transistors have become the key ingredient of all digital circuits, including computers. Today's latest microprocessor contains tens of millions of microscopic transistors.
Prior to the invention of transistors, digital circuits were composed of vacuum tubes, which had many disadvantages. They were much larger, required more energy, dissipated more heat, and were more prone to failures. It's safe to say that without the invention of transistors, computing as we know it today would not be possible.
The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube,allowing computers to become smaller, faster, cheaper,more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages,which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.

Third Generation - 1964-1971: Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
A nonmetallic chemical element in the carbon family of elements. Silicon - atomic symbol "Si" - is the second most abundant element in the earth's crust, surpassed only by oxygen. Silicon does not occur uncombined in nature. Sand and almost all rocks contain silicon combined with oxygen, forming silica. When silicon combines with other elements, such as iron, aluminum or potassium, a silicate is formed. Compounds of silicon also occur in the atmosphere, natural waters,many plants and in the bodies of some animals.
Silicon is the basic material used to make computer chips, transistors, silicon diodes and other electronic circuits and switching devices because its atomic structure makes the element an ideal semiconductor. Silicon is commonly doped, or mixed,with other elements, such as boron, phosphorous and arsenic, to alter its conductive properties.
A chip is a small piece of semi conducting material(usually silicon) on which an integrated circuit is embedded. A typical chip is less than ¼-square inches and can contain millions of electronic components(transistors). Computers consist of many chips placed on electronic boards called printed circuit boards. There are different types of chips.
The history of computer development is often referred to in reference to the different generations of computing devices. A generation refers to the state of improvement in the product development process. This term is also used in the different advancements of new computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and computer memory has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.
Each generation of computers is characterized by major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices. Read about each generation and the developments that led to the current devices that we use today.

First Generation - 1940-1956: Vacuum Tubes

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. A magnetic drum,also referred to as drum, is a metal cylinder coated with magnetic iron-oxide material on which data and programs can be stored. Magnetic drums were once use das a primary storage device but have since been implemented as auxiliary storage devices.
The tracks on a magnetic drum are assigned to channels located around the circumference of the drum, forming adjacent circular bands that wind around the drum. A single drum can have up to 200 tracks. As the drum rotates at a speed of up to 3,000 rpm, the device's read/write heads deposit magnetized spots on the drum during the write operation and sense these spots during a read operation. This action is similar to that of a magnetic tape or disk drive.
They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Machine languages are the only languages understood by computers. While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers. Computer Programmers, therefore, use either high level programming languages or an assembly language programming. An assembly language contains the same instructions as a machine language, but the instructions and variables have names instead of being just numbers.
Programs written in  high level programming languages retranslated into assembly language or machine language by a compiler. Assembly language program retranslated into machine language by a program called an assembler (assembly language compiler).
Every CPU has its own unique machine language. Programs must be rewritten or recompiled, therefore, to run on different types of computers. Input was based onpunch card and paper tapes, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.
Acronym for Electronic Numerical Integrator And Computer, the world's first operational electronic digital computer, developed by Army Ordnance to compute World War II ballistic firing tables. The ENIAC, weighing 30 tons, using 200 kilowatts of electric power and consisting of 18,000 vacuum tubes,1,500 relays, and hundreds of thousands of resistors,capacitors, and inductors, was completed in 1945. In addition to ballistics, the ENIAC's field of application included weather prediction, atomic-energy calculations, cosmic-ray studies, thermal ignition,random-number studies, wind-tunnel design, and other scientific uses. The ENIAC soon became obsolete as the need arose for faster computing speeds.

Second Generation - 1956-1963: Transistors

Transistors replaced vacuum tubes and ushered in the second generation computer. Transistor is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit. Invented in 1947 at Bell Labs, transistors have become the key ingredient of all digital circuits, including computers. Today's latest microprocessor contains tens of millions of microscopic transistors.
Prior to the invention of transistors, digital circuits were composed of vacuum tubes, which had many disadvantages. They were much larger, required more energy, dissipated more heat, and were more prone to failures. It's safe to say that without the invention of transistors, computing as we know it today would not be possible.
The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube,allowing computers to become smaller, faster, cheaper,more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages,which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.

Third Generation - 1964-1971: Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
A nonmetallic chemical element in the carbon family of elements. Silicon - atomic symbol "Si" - is the second most abundant element in the earth's crust, surpassed only by oxygen. Silicon does not occur uncombined in nature. Sand and almost all rocks contain silicon combined with oxygen, forming silica. When silicon combines with other elements, such as iron, aluminum or potassium, a silicate is formed. Compounds of silicon also occur in the atmosphere, natural waters,many plants and in the bodies of some animals.
Silicon is the basic material used to make computer chips, transistors, silicon diodes and other electronic circuits and switching devices because its atomic structure makes the element an ideal semiconductor. Silicon is commonly doped, or mixed,with other elements, such as boron, phosphorous and arsenic, to alter its conductive properties.
A chip is a small piece of semi conducting material(usually silicon) on which an integrated circuit is embedded. A typical chip is less than ¼-square inches and can contain millions of electronic components(transistors). Computers consist of many chips placed on electronic boards called printed circuit boards. There are different types of chips. For example, CPU chips (also called microprocessors) contain an entire processing unit, whereas memory chips contain blank memory.
Semiconductor is a material that is neither a good conductor of electricity (like copper) nor a good insulator (like rubber). The most common semiconductor materials are silicon and germanium. These materials are then doped to create an excess or lack of electrons.
Computer chips, both for CPU and memory, are composed of semiconductor materials. Semiconductors make it possible to miniaturize electronic components, such as transistors. Not only does miniaturization mean that the components take up less space, it also means that they are faster and require less energy.
For example, CPU chips (also called microprocessors) contain an entire processing unit, whereas memory chips contain blank memory.
Semiconductor is a material that is neither a good conductor of electricity (like copper) nor a good insulator (like rubber). The most common semiconductor materials are silicon and germanium. These materials are then doped to create an excess or lack of electrons.
Computer chips, both for CPU and memory, are composed of semiconductor materials. Semiconductors make it possible to miniaturize electronic components, such as transistors. Not only does miniaturization mean that the components take up less space, it also means that they are faster and require less energy.

Fourth Generation - 1971-Present: Microprocessors

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits we rebuilt onto a single silicon chip. A silicon chip that contains a CPU. In the world of personal computers,the terms microprocessor and CPU are used interchangeably. At the heart of all personal computers and most workstations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.

Three basic characteristics differentiate microprocessors:

• Instruction Set: The set of instructions that the microprocessor can execute.


• Bandwidth: The number of bits processed in a single instruction.


• Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.

In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that runs at 50MHz is more powerful than a 16-bitmicroprocessor that runs at 25MHz.
What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004chip, developed in 1971, located all the components of the computer - from the central processing unit and memory to input/output controls - on a single chip.
Abbreviation of central processing unit, and pronounced as separate letters. The CPU is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power,the CPU is the most important element of a computer system.
On large machines, CPUs require one or more printed circuit boards. On personal computers and small workstations, the CPU is housed in a single chip called a microprocessor.
Two typical components of a CPU are:

• The arithmetic logic unit (ALU), which performs arithmetic and logical operations.


• The control unit, which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.

In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUI's, the mouse and handheld devices

Fifth Generation - Present and Beyond: Artificial Intelligence

Fifth generation computing devices, based on artificial intelligence, are still in development,though there are some applications, such as voice recognition, that are being used today.
Artificial Intelligence is the branch of computer science concerned with making computers behave like humans. The term was coined in 1956 by John McCarthy at the Massachusetts Institute of Technology. Artificial intelligence includes:

• Games Playing: programming computers to play games such as chess and checkers


• Expert Systems: programming computers to make decisions in real-life situations (for example, some expert systems help doctors diagnose diseases based on symptoms)


• Natural Language: programming computers to understand natural human languages


• Neural Networks: Systems that simulate intelligence by attempting to reproduce the types of physical connections that occur in animal brains


• Robotics: programming computers to see and hear and react to other sensory stimuli

Currently, no computers exhibit full artificial intelligence (that is, are able to simulate human behavior). The greatest advances have occurred in the field of games playing. The best computer chess programs are now capable of beating humans. In May,1997, an IBM super-computer called Deep Blue defeated world chess champion Gary Kasparov in a chess match.
In the area of robotics, computers are now widely used in assembly plants, but they are capable only of very limited tasks. Robots have great difficulty identifying objects based on appearance or feel, and they still move and handle objects clumsily.
Natural-language processing offers the greatest potential rewards because it would allow people to interact with computers without needing any specialized knowledge. You could simply walk up to a computer and talk to it. Unfortunately, programming computers to understand natural languages has proved to be more difficult than originally thought. Some rudimentary translation systems that translate from one human language to another are in existence, but they are not nearly as good as human translators.
There are also voice recognition systems that can convert spoken sounds into written words, but they do not understand what they are writing; they simply take dictation. Even these systems are quite limited -- you must speak slowly and distinctly.
In the early 1980s, expert systems were believed to represent the future of artificial intelligence and of computers in general. To date, however, they have not lived up to expectations. Many expert systems help human experts in such fields as medicine and engineering, but they are very expensive to produce and are helpful only in special situations.
Today, the hottest area of artificial intelligence is neural networks, which are proving successful in an umber of disciplines such as voice recognition and natural-language processing.
There are several programming languages that are known as AI languages because they are used almost exclusively for AI applications. The two most common are LISP and Prolog.

computer hardware

Information And Communication Technology

INTRODUCTION TO COMPUTER NETWORKS AND COMMUNICATIONS

COMPUTER NETWORK

A computer network is a system of interconnected computers and peripheral devices. For example, it may connect computers, printers, scanners and cameras. Using hardware and software, these interconnected computing devices can communicate with each other through defined rules of data communications. In a network, computers can exchange and share information and resources.

A computer network may operate on wired connections or wireless connections. When two or more networks are linked or connected and are able to communicate with one another using suitable hardware and software, it is called an internetwork.

COMMUNICATIONS

Communications is about the transfer of information from a sender, across a distance, to a receiver. Using electricity, radio waves or light, information and data in the form of codes are transmitted through a physical medium such as wire, cable, or even the atmosphere.

Therefore, in order to make communications possible from computers, across telephones and radios and back to computers and other digital devices again, there must be a signal translator, which we call – a modem. The modem, which is short for modulator or demodulator, converts digital signals into analog and back again into digital signals for information to move across the telephone line.

CONNECTIONS FOR NETWORKING

• a physical medium – to allow data to travel across it from device to device
• a set of rules called protocols to ensure that interconnected computing devices have the same standards for exchange of information to occur smoothly.
• a system application for managing network information flow to ensure that data transmission sent from one device is received by the intended receiver.

computer topology

The physical and logical structure of a network. Physical topology refers to the physical layout of a network, specifically the physical positioning of the nodes and the circuits that interconnect them. Logical topology refers to the manner in which devices logically interconnect in a network, and may differ considerably from the physical topology. For example, an Ethernet LAN segment may comprise a number of workstations and peripheral devices that interconnect through a hub, with each device connecting directly to a hub port.The physical topology is that of a star, but the logical topology is that of a bus.That is to say that, although the devices connect to the hub over circuits that emanate from the hub like the rays of a star, they interconnect through a collapsed bus, or common electrical path, housed within the hub. LAN and WAN topologies variously include bus, mesh, partial mesh, ring, star, and tree. See also bus, Ethernet, hub, LAN, logical, mesh topology, physical, ring, segment, star topology, tree, and WAN.

motherboard

Motherboard

Find the motherboard standoffs (spacers) that should have come with the case. They are screws, usually brass, with large hexagonal heads that are tapped so you can fasten screws into the top. These hold the motherboard up off the case preventing a short-circuit. Set these aside.

I/O Panel Shield of an ATX Motherboard

Remove the I/O Shield from the back of the case where the ports on the back of the motherboard will fit, and put in the I/O Shield that came with your motherboard. There may be small metal tabs on the inside of this face plate, if so you may have to adjust them to accommodate the ports on the back of the motherboard.
Some case styles make it difficult to install the motherboard or the CPU with the power supply installed. If the power supply is in your way, take it out and set it aside (we'll put it back in later).
Now locate the screw holes on your motherboard and find the corresponding holes on the motherboard plate (or tray) in the case. Put a standoff in each of these holes on the tray and position the motherboard so that you can see the holes in the top of the standoffs through the screw holes in the motherboard.
Now is the time to make sure the ports on the motherboard are mating with the backplate you just installed, and make any necessary adjustments. The small metal tabs are intended to make contact with the metal parts of the connections on the back of the motherboard and ground them, but you may have to bend these tabs a bit to get the ports all properly mounted, this is where those needle-nose pliers may come in handy.