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LIFE SKILLS

WIRELESS NETWORKS

One of the exciting new developments is the deployment of wireless networks. There are two main types of wireless networks today: Cellular and WIFI.

Cellular networks are used primarily for voice coverage along with very limited data capabilities. The main advantage of cellular technology is its long-range capability. In many parts of the world, there is persistent cellular connectivity available. (for example users on some of the high-speed trains in Europe and Asia can even use their cell phones while travelling).

Advantages of Cellular Technology

  • Cellular technology is very good for voice communication.
  • Very wide acceptance worldwide

Disadvantages of Cellular Technology

  • It has very limited (i.e., slow) data capability.
  • All of the major carriers are working on next generation cellular technology that will dramatically increase the data capabilities.

WIFI is based on existing wired computer network technology (LAN). It provides very high speed but with a much short range of service. It is available in limited locations (commonly called ‘hot spots’.) It does not provide voice Communication, just Internet access. Additionally, WIFI access requires a specific device or a special add on to other devices (laptop and PC). Today, only a relatively small number of users have appropriate devices. However, the expectation is that this technology will gain very rapid popularity.

Advantages of WIFI Technology

  • WIFI is excellent for data communication.

Disadvantages of WIFI Technology

  • It is limited in availability
  • Very expensive. However it is expected that as the availability increases, the costs will drop.

Cloud Computing

Cloud Computing is a technology that uses the internet and central remote servers to maintain data and applications. Cloud computing allows consumers and businesses to use applications without installation and access their data at any computer with internet connection. Cloud computing relies on sharing of resources to achieve economies of scale similar to a utility (like the electricity grid) over a network. At the foundation of cloud computing is the broader concept of converged infrastructure and shared services

A simple example of cloud computing is Yahoo email, Gmail, or Hotmail etc. All you need is just an internet connection and you can start sending emails. The server and email management software is all on the cloud (internet) and is totally managed by the cloud service provider Yahoo, Google etc

Cloud computing is so named because the information being accessed is found in the “clouds”, and does not require a user to be in a specific place to gain access to it. Companies may find that cloud computing allows them to reduce the cost of information management, since they are not required to own their own servers and can use capacity leased from third parties.

Advantages of Cloud Computing

If used properly and to the extent necessary, working with data in the cloud can benefit all types of businesses. The following are some of the advantages of this technology:

  • Cost Efficient. Cloud computing is probably the most cost efficient method to use, maintain and upgrade. Traditional desktop software costs companies a lot in terms of finance. Adding up the licensing fees for multiple users can prove to be very expensive for the establishment concerned. The cloud, on the other hand, is available at much cheaper rates and hence, can significantly lower the company’s IT expenses.
  • Almost Unlimited Storage. Storing information in the cloud gives you almost unlimited storage capacity. Hence, you no more need to worry about running out of storage space or increasing your current storage space availability.
  • Backup and Recovery. Since all your data is stored in the cloud, backing it up and restoring the same is relatively much easier than storing the same on a physical device. Furthermore, most cloud service providers are usually competent enough to handle recovery of information. Hence, this makes the entire process of backup and recovery much simpler than other traditional methods of data storage.
  • Automatic Software Integration. In the cloud, software integration is usually something that occurs automatically. This means that you do not need to take additional efforts to customize and integrate your applications as per your preferences. Cloud computing also allows you to customize your options with great ease.
  • Easy Access to Information. Once you register yourself in the cloud, you can access the information from anywhere, where there is an Internet connection. This convenient feature lets you move beyond time zone and geographic location
  • Quick Deployment. Lastly and most importantly, cloud computing gives you the advantage of quick deployment. Once you opt for this method of functioning, your entire system can be fully functional in a matter of a few minutes. Of course, the amount of time taken here will depend on the exact kind of technology that you need for your business.

Disadvantages of Cloud Computing

In spite of its many benefits, as mentioned above, cloud computing also has its disadvantages. Businesses, especially smaller ones, need to be aware of these cons before going in for this technology.

  • Technical Issues .Though it is true that information and data on the cloud can be accessed anytime and from anywhere at all, there are times when this system can have some serious dysfunction. You should be aware of the fact that this technology is always prone to outages and other technical issues. Even the best cloud service providers run into this kind of trouble, in spite of keeping up high standards of maintenance. Besides, you will need a very good Internet connection to be logged onto the server at all times. You will invariably be stuck in case of network and connectivity problems.
  • Security in the Cloud. The other major issue while in the cloud is that of security issues. Before adopting this technology, you should know that you will be surrendering all your company’s sensitive information to a third-party cloud service provider. This could potentially put your company to great risk. Hence, you need to make absolutely sure that you choose the most reliable service provider, who will keep your information totally secure.
  • Prone to Attacks. Storing information in the cloud could make your company vulnerable to external hack attacks and threats. As you are well aware, nothing on the Internet is completely secure and hence, there is always the lurking possibility of stealth of sensitive data.

PERSONAL DIGITAL ASSISTANTS (PDA)

PDAs are small devices which can be loosely thought of as very small, limited functionality PCs. They do a very good job of storing contact lists and calendars. Some can be used to access email remotely.

In order to make them fit easily in a pocket or purse; PDAs have very small

screens and either no keyboard or a very small one.

Advantages of PDAs

  • Can organize daily schedules
  • Can take notes
  • Can record voice memos and lectures
  • Can write and rehearse PowerPoint presentations
  • Able to view journal articles,  photos and movies

 Disadvantages of PDAs

  • You can’t display a complete page of text or graphics on a PDA
  • Data entry, beyond short messages, is difficult or impossible.
  • Screen size is small
  • Battery life is limited
  • Limited memory capacity.

E-learning

E-Learning is the use of technology to enable people to learn anytime and anywhere.  E-learning applications and processes include Web-based learning, computer-based learning, virtual education opportunities and digital collaboration. Content is delivered via the Internet, intranet/extranet, audio or video tape, satellite TV, and CD-ROM. It can be self-paced or instructor-led and includes media in the form of text, image, animation, streaming video and audio.

Electronic commerce

Electronic commerce, commonly known as e-commerce is the process used to distribute, buy, sell or market goods and services, and the transfer of funds online, through electronic communications or networks. Electronic commerce i basically began (although debated) in 1994 when Jeff Bezos started Amazon.com out of his own garage. Well known e-commerce stores include sites like eBay, Dell, Walmart and many more.

Social networking

A social networking service is an online service, platform, or site that focuses on facilitating the building of social networks or social relations among people who, for example, share interests, activities, backgrounds, or real-life connections. A social network service consists of a representation of each user (often a profile), his/her social links, and a variety of additional services. Most social network services are web-based and provide means for users to interact over the Internet, such as e-mail and instant messaging. Social networking sites allow users to share ideas, activities, events, and interests within their individual networks.

The main types of social networking services are those that contain category places (such as former school year or classmates), means to connect with friends (usually with self-description pages), and a recommendation system linked to trust. Popular methods now combine many of these, with American-based services Facebook, Google+, and Twitter widely used worldwide.

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ICT ETHICS AND LEGISLATIONS

Meaning of ICT ethics

Ethics is a set of moral principles that govern the behavior of a group or individual. Therefore, ICT ethics is set of moral principles that regulate the use of ICT.

Ethics are grounded in the notion of responsibility (as free moral agents, individuals, Organizations, and societies are responsible for the actions that they take) and Accountability (individuals, organizations, and society should be held accountable to others for the consequences of their actions).

The Importance of Ethics in ICT (Check)

Information is a source of power and, increasingly, the key to prosperity among those with access to it. Consequently, developments in ICT also involve social and political relationships. This makes ethical considerations on how important information is used.

Electronic systems now reach into all levels of government, into the workplace, and into private lives to such an extent that even people without access to these systems are affected in significant ways by them. New ethical and legal decisions are necessary to balance the needs and rights of everyone.

As in other new technological arenas, legal decisions lag behind technical developments. Ethics fill the gap as people negotiate how use of electronic information should proceed. The following notes define the broad ethical issues now being negotiated. Since laws deciding some aspects of these issues have been made, these notes should be read in conjunction with Legal Issues in Electronic Information Systems.

Unethical behavior in ICT

Unethical behavior in ICT is the incorrect use of ICT in a way that disturbs privacy of others or their intellectual property rights thereby creating ethical dilemmas. Unethical behavior in ICT includes:

1. Software piracy

Software piracy is the unauthorized copying of software. Most retail programs are licensed for use at just one computer site or for use by only one user at any time. By buying the software, you become a licensed user rather than an owner. You are allowed to make copies of the program for backup purposes, but it is against the law to give copies to friends and colleagues. Another type of software piracy is software counterfeiting which occurs when fake copies of software are produced in such a way that they appear to be authentic.

2. Unauthorized access or Hacking

Hacking or unauthorized access is breaking into computer systems, it entails approaching, trespassing within, communicating with, storing data in, retrieving data from, or otherwise intercepting and changing computer resources without consent. These break-ins may cause damage or disruption to computer systems or networks.

3. Plagiarism check)

Plagiarism is the practice of taking someone else’s work or ideas and passing them off as one’s own. Plagiarism was around long before the Internet but the advent of the internet has increased cases of plagiarism and made it difficult to detect.’

4. Spamming

Spamming is flooding the Internet with many copies of the same message, in an attempt to force the message on people who would not otherwise choose to receive it. It is normally done through unsolicited bulk emails. Most spam is commercial advertising, often for dubious products, get-rich-quick schemes, or quasi-legal services.

Every time a “spammer” sends out email spam, the entire Internet community has to bear the cost, in particular the recipients and the ISPs at the receiving end. It wastes a lot of recipients’ time and disk space.

Spam also ties up bandwidth and resources on computers and routers all over the Internet. Every unwanted email message adds to the total cost of operating the networks of computers which form the Internet. Spam can disrupt a network by crashing mail servers and filling up hard drives. Spam also constitutes an invasion of Internet users’ online privacy.

5. Phishing

Phishing is the act of sending an e-mail to a user falsely claiming to be an established legitimate enterprise in an attempt to trick the user into surrendering private information that will be used for identity theft. The e-mail directs the user to visit a Web site where they are asked to update personal information, such as passwords and credit card, social security, and bank account numbers, that the legitimate organization already has. The Web site, however, is bogus and set up only to steal the user information.

Reasons for unethical behavior in ICT

  • Pressure can drive people to do things they wouldn’t normally do. For example pressure to meet unrealistic deadlines and expectations, from co-workers, bosses, or customers, can lead some people to engage in unethical activities or at least look the other way.
  • Some people make unethical choices because they are ignorant of what really is the right thing to do. Often, ethical problems are complicated, and the proper choice may not be obvious.
  • Some people behave unethically because of self-interest, need for personal gain, ambition or downright greed.
  • Misguided loyalty is another reason for unethical conduct on the job. People sometimes lie because they think in doing so they are being loyal to the organization or to their bosses. For example, managers at automobile companies who hide or falsify information about defects that later cause accidents and kill people.
  • There are those people who never learned or do not care about ethical values. Since they have no personal ethical values, they do not have any basis for understanding or applying ethical standards in their work. These people do not think about right and wrong. They only think, “What’s in it for me?” and “Can I get away with it?”
  • Competition for scarce resources, power or position can also cause individuals to engage in unethical behaviors.

Measures for controlling unethical behavior in ICT

There are a number of ways which managers can adopt to reduce unethical behavior in their organizations. These include:

  • Hiring of individuals with high ethical standards;
  • Establishing code of ethics and decision rules;
  • Defining job goals and performance appraisal mechanism;
  • Providing ethical training;
  • Conducting social audits and providing support to individuals facing ethical dilemmas.

Sources of ICT legislation

Legislation is the laws governing everybody in a country while ICT legislation refers to the laws governing the ICT sector. In Kenya, the ICT sector is still emerging and there are no specific laws for the sector. However, there are several affecting the ICT sector in Kenya. These are:

  • The following laws govern/affect the sector:
  • Kenya Communications Act 1998
  • Postal Corporation Kenya Act 1998
  • Kenya Broadcasting Corporation Act
  • The Telegraph Press Message Act 1983
  • The Science & Technology Act
  • State Corporations Act
  • The Education Act

Draft legislation that is expected to be passed soon and which are likely to affect the ICT sector includes:

  • Broadcasting Bill
  • Freedom of Information
  • Electronic Transaction bill
  • Mobile Telephone Reprogramming

Other laws that are used to govern the sector include the ‘Common law’ and the ‘Statute law’ of the United Kingdom

 ICT policy

A policy can be defined as a plan of action to guide decisions and actions. The term may apply to government, organizations and individuals. Policies in short can be understood as mechanisms arranged to reach explicit goals.

An ICT policy can therefore be defined as the rules and regulations set by the organization that determines the type of internal and external ICT resources employees can access, the kinds of programs they may install on their own computers as well as their authority for accessing network resources.

Benefits of policies

  1. Help save time
  2. Help prevent managerial mistakes
  3. Improve consistency of decision making
  4. Focus decisions towards business goals

Data Protection (Information Privacy)

Data Protection is achieved through the Data Protection Act. The Data Protection Act was developed to give protection and lay down the rules about how personal data can be used. It was created to protect individuals from misuse of this data. It governs the collection and processing of data by organizations and the individual rights to access the data if they wish.

Principles of Data Protection Act

  • Data must be kept secure;
  • Data stored must be relevant;
  • Data stored must be kept no longer than necessary;
  • Data stored must be kept accurate and up-to-date;
  • Data must be obtained and processed lawfully;
  • Data must be processed within the data subject rights;
  • Data must be obtained and specified for lawful purposes;
  • Data must not be transferred to countries without adequate data protection laws.

Copyright

Copyright is achieved through the Copyright, Design and Patents Act of 1988. This Act was introduced to protect people who have created original pieces of work like Books, Music, Films, Games and Applications, etc.

Two main purposes of the Act:

  • To ensure people are rewarded for their endeavours.
  • To give protection to the copyright holder if someone tries to steal their work.

The Act protects a wide range of work both written and computer based and Includes:

  • Copying Software;
  • Copying or Downloading music;
  • Copying images or photographs from the Web;
  • Copying text from web pages

The Computer Misuse Act

The Computer Misuse Act (1990) was introduced to secure computer material against unauthorised access or modification.  Before this act was enacted, it was not possible to prosecute a ‘hacker’. Three categories of criminal offences were established to cover the following conduct:

  • Unauthorised access to computer material (viewing data which you are not authorized to see).
  • Unauthorised access with intent to commit or facilitate commission of further offences (hacking).
  • Unauthorised modification of computer material.
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INTRODUCTION TO COMMUNICATION NETWORK

Meaning of a communication network

 A communication network can be defined as a set of devices (often referred to as nodes) connected by communication links and is used to transfer information between users located at various geographical points.

A communication network can also be defined as a collection of computers, printers and other equipment that is connected together so that they can communicate with each other. 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.

Uses/ benefits of communication networks

1. Resource sharing. Resource sharing is one of the most popular uses of computer networks in the business applications. For Instance, a printer is shared in a network and hence saves a lot of investment in hardware. Other resources that can be shared include fax machines and modems

2. File sharing. A network makes it easy for everyone to access the same file and prevents people from accidentally creating different versions of the same file.

In a larger office, you can use e-mail and instant messaging tools to communicate quickly and to store messages for future reference.

3. Collaboration A network allows employees to share files, view other people’s work, and exchange ideas more efficiently

4. Organization: A variety of scheduling software is available that makes it possible to arrange meetings without constantly checking everyone’s schedules. This software usually includes other helpful features, such as shared address books and to-do lists.

 5. Teleconferencing: Teleconferencing allows conferences to occur without the
participants being in the same place. Applications include video conferencing where participants can see as well as talk to one another

6. Mobile telephony: In the past two parties wishing to use the services of the telephone company had to be linked by a fixed physical connection. Today’s cellular networks make it possible to maintain wireless phone connections even while traveling
over large distances.

7. E-Business. E-business or electronic business refers to conducting business transactions on the internet, not only limited to buying and selling but also servicing customers and collaborating with business partners.

8. Online Education. With network connections, online education is made possible. Students at any location around the world can participate in an online classroom, download tutorial questions and submit their assignments.

9. E-Banking. E-banking or electronic banking is the most popular banking facility nowadays. It handles all types of banking transactions like account management, fund transfer and payments primarily over the internet. User can pay bills, check the account balance and transfer money to other parties, using e-banking facilities twenty four hours a day and seven days a week.

10. Long Distance Communication. Long distance communication is made easy via network availability. Communication is possible via voice, text or video. The cost of having this type of communication is cheaper than making a normal phone call and definitely faster and more effective than corresponding via letters of fax.

11. Centralized software management. Software can be loaded on one computer (the file server) eliminating that need to spend time and energy installing updates and tracking files on independent computers

12. Workgroup computing. Workgroup software (such as Microsoft BackOffice) allows many users to work on a document or project concurrently

Interactive entertainment

 Disadvantages of networks

  • Expensive Set Up: The initial set up cost of a computer network can be high depending on the number of computers to be connected. Costly devices like servers, routers, switches, hubs and cables can add up to the cost of installing a computer network.
  • Managing a large network is complicated and requires hiring somebody with technical skills.
  • Dependency on the Main File Server: In case the main File Server of a computer network breaks down, the system becomes useless. In case of big networks, the File Server should be a powerful computer, which often makes it expensive.
  • Rapid Spread of Computer Viruses: If any computer system in a network gets affected by computer virus, there is a possible threat of other systems getting affected too. Viruses get spread on a network easily because of the interconnectivity of workstations. Such spread can be dangerous if the computers have important database which can get corrupted by the virus.
  • There is a danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse, eg a firewall.
  •  As traffic increases on a network, the performance degrades unless the network is designed properly.

Types of Computer Networks

Below is a list of the most common types of computer networks.

Local area network (LAN)

A local area network is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. Current LANs are most likely to be based on Ethernet technology. For example, a library may have a wired or wireless LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet.

A metropolitan area network (MAN)

A metropolitan area network is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city.

A wide area network (WAN)

A wide area network is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries. This is contrasted with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies..

OTHERS

 Other networks include the following:

A campus area network (CAN)

A campus area network is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.

In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN).

Personal area network (PAN)

A personal area network is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet (approximately 6-9 meters).

Network topologies

Network topologies refer to the way in which computers in a network are linked together. It determines the data path that may be used between any two communicating computers in the network. The following are the common topologies

This is a network topology in which all the nodes are connected to a common transmission medium with two endpoints (this is the ‘bus’, which is also commonly referred to as the backbone or trunk). All data that is transmitted between nodes in the network is transmitted over this common transmission medium and is received by all nodes in the network simultaneously.

Note:

The two endpoints of the common transmission medium are normally terminated with a device called a terminator, which dissipates or absorbs the energy that remains in the signal to prevent the signal from being reflected back onto the transmission medium. Otherwise it causes interference resulting in degradation of the signals on the transmission medium.

Advantages of a Linear Bus Topology

  • Easy to connect a computer or peripheral to a linear bus.
  • Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology

  • Entire network shuts down if there is a break in the main cable.
  • Terminators are required at both ends of the backbone cable.
  • Difficult to identify the problem if the entire network shuts down.
  • Not meant to be used as a stand-alone solution in a   large building.

Star

Also known as a star network, a star topology is one of the most common network setups where each of the devices and computers on a network connect to a central hub as shown in the diagram above.

Advantages

  1. A failure on one link does not affect other links as they use different routes.
  2. It provides shorter data paths. Since the central site is connected directly to the destination site, data does not have to travel through any intermediate sites, thus providing a shorter data path.
  3. It is also easier and less expensive to extend a star topology compared to the bus or ring topologies.
  4. Easy to detect faults and to remove parts.

Disadvantages

  1. Any failure at the central site or hub can cause the entire network to go down.
  2. In case the central connection point gets overloaded with data, the performance of the entire network gets affected.
  3. Requires more cable length than a linear topology.
  4. More expensive than linear bus topologies because of the cost of the central node

Ring

In a ring topology, each node in the network is connected to the next node forming a closed loop giving the appearance of a ring-like structure. Thus each device is connected directly to two other devices, one on each side of it. When this topology is used, it connects nodes using two parallel paths of data.

Advantages

  1. It also offers high bandwidth and can span long distances

Disadvantages

  1. It is expensive when it comes to expanding the topology
  2. It may also be difficult to install.
  3. Ring topology is suitable for only a few nodes

Tree

A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable (See fig. 4). Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.

Advantages of a Tree Topology

  • Point-to-point wiring for individual segments.
  • Supported by several hardware and software venders.

Disadvantages of a Tree Topology

  • Overall length of each segment is limited by the type of cabling used.
  • If the backbone line breaks, the entire segment goes down.
  • More difficult to configure and wire than other topologies.

 

Combined (Hybrid) (Check if it is similar to mesh topology)

Hybrid Topology

A hybrid topology is a combination of any two or more network topologies in such a way that the resulting network does not have one of the standard forms. For example, a tree network connected to a tree network is still a tree network, but two star networks connected together exhibit hybrid network topologies. A hybrid topology is always produced when two different basic network topologies are connected.

Advantage

Hybrid topology allows coexistence and cohabitation by integrating different network topologies to work together.

Disadvantage

it is costly to support and maintain them.

Telecommunications technology

 Telecommunications is the exchange of information over significant distances by electronic means. Telecommunications technology includes anything used by humans to communicate information over a distance. The concept has been around since the early days of human history, when smoke signals and drums were used to inform a person or groups of people of an event or situation. However, major breakthroughs since the late 1800s have brought the field of telecommunications into the modern age. More recent developments include the telephone, radio, television, fax machine and computer, each with its own unique properties to benefit the information exchange of mankind.

A basic telecommunication system consists of three elements:

  • a transmitter that takes information and converts it to a signal;
  • a transmission medium that carries the signal; and,
  • a receiver that receives the signal and converts it back into usable information.

Common Telecommunication Technologies

1. Telephone

One of the most prevalent telecommunications devices is the phone, an instrument which transfers vocal information from place to place. Two main types of phones are used in modern society: the analog-based fixed-line telephone and the satellite-based cellular phone.

2. Radio and Television

The broadcast system, which features the radio and television networks, uses a different format to transmit information. Both systems use electromagnetic waves that send audio and video information from one location to another. This can either be accomplished through an analog or digital method.

3. Computer Networks

Networked computers are very common in the modern world and are either connected to a local-area network or the world wide web. This telecommunications technology allows users to send and receive a variety of formatted information such as text via emails or video with webcams. Different types of connections are available to make this technology function. Early connective techniques included fixed-line analog-to-digital modems, while newer methods including Ethernet lines and wireless connections utilizing electromagnetic waves.

 Transmission Media

For effective communication to take place, communication media is required to connect the transmitter and the receiver.  The diagram below gives a clear picture of different type of transmission media.

 

Guided Transmission Media

Guided/physical/non-wireless/bounded media have a physical link between sender and receiver. There are three categories of guided media: twisted-Pair, coaxial and fiber-optic.

Twisted-Pair Cable

A twisted consist of two conductors (usually copper), each with its own colored plastic insulation. In the past, two parallel wires were used for communication. However, electromagnetic interference from devices such as a motor can create over noise those wires. If the two wires are parallel, the wire closest to the source of the noise gets more interference than the wire further away. This results in an uneven load and a damaged signal.

If, however, the two wires are twisted around each other at regular intervals (between 2 to 12 twist per foot), each wire is closer to the noise source for half the time and the further away the other half. With the twisting interference can be equalized for both wires. Twisting does not always eliminate the impact of noise, but does significantly reduce it

Twisted cable comes in two forms: unshielded and shielded.

Unshielded Twisted Pair (UTP) cable

UTP consists of a number of twisted pairs with simple plastic casing. UTP is commonly used in telephone system.

 

Shielded Twisted Pair (STP) cable

STP includes shielding to reduce cross talk as well as to limit the effects of external interference. For most STP cables, this means that the wiring includes a wire braid inside the cladding or sheath material as well as a foil wrap around each individual wire. This shield improves the cable’s transmission and interference characteristics, which, in turn, support higher bandwidth over longer distance than UTP.

Coaxial Cable

Coaxial cable, commonly called coax, has two conductors that share the same axis. A solid copper wire runs down the center of the cable, and this wire is surrounded by plastic foam insulation. The foam is surrounded by a second conductor, wire mesh tube, metallic foil, or both. The wire mesh protects the wire from EMI. It is often called the shield. A tough plastic jacket forms the cover of the cable, providing protection and insulation.

Fiber Optic Cable: fiber optic cable transmits light signals rather than electrical signals. It is enormously more efficient than the other network transmission media. As soon as it comes down in price (both in terms of the cable and installation cost), fiber optic will be the choice for network cabling.

A light pulse can be used to signal a ‗1‘ bit; the absence of a pulse signals a ‗0‘ bit. Visible light has a frequency of about 108 MHz, so the bandwidth of an optical transmission system is potentially enormous.

An optical transmission system has three components: the transmission medium, the light source and the detector. The transmission medium is an ultra-thin fiber of glass or fused silica. The light source is either a LED (Light Emit Diode) or a laser diode, both of which emits light pulses when a electrical current is applied. The detector is a photo diode, which generates an electrical pulse when light falls on it.

A cable may contain a single fiber, but often fibers are bundled together in the center of the cable. Optical fibre are smaller and lighter than copper wire. One optical fiber is approximately the same diameter as a human hair.

Advantages of Fiber Optic

  • Noise resistance: it is immune to Electromagnetic Interference (EMI)
  • Less signal attenuation: signal can run for miles without requiring regeneration
  • Higher bandwidth: fiber optic cable can support dramatically higher bandwidths (and hence data rate) than all other cables. Currently, data rates and bandwidth utilization over fiber-optic cable are limited not by the medium but by the signal generation and reception technology available. A typical bandwidth for fiber optic is 100Mbps to 1Gbps.

Disadvantages of Fiber Optic

  • Cost : most expensive among all the cables
  • Installation / maintenance: is high
  • Fragility : glass fiber is more easily broken than wire

Unguided Transmission Media

Unguided/non-physical/wireless/unbounded media have no physical link between sender and receiver.

There has been increasing need for mobile users to connect to a network. The answer for their needs is wireless. In wireless communications, space (air) is the medium for the signals.

Wireless networking has some advantages over wired networking:

  • No wires needed. Running wires can be difficult in some cases; such as wiring an existing building, wiring between buildings, wiring across mountains, etc.
  • Staying connected is important for mobile users. Wireless networks allow users stay connected more hours each day. Users with laptops may roam their work space without losing network connection and without logging into another machine. This increases the productivity of workers.
  • Wireless networks can grow without much difficulty compared with wired networks. Making a wired network larger often involves wiring and usually costly.
  • Wireless networks are not confined to an area. There is no long term commitment as in the wired networks.

Categories of unguided media

 There are two categories of unguided media. These are:

  • Radio transmission: These are systems for AM or FM radio. They are one form of communications and not used for computer networks.
  • Microwave transmission: We can classify them into three categories; Terrestrial microwave, Satellite and Infra Transmission

Terrestrial Microwave

Microwaves do not follow the curvature of the earth therefore require line of sight transmission and reception equipment. The distance coverable by line of sight signals depends to a large extend on the height of the antenna: the taller the antenna, the longer the sight distance. Height allows the signals to travel farther without being stopped by the curvature of the earth and raises the signals above many surface obstacles, such as low hills and tall buildings that would otherwise block transmission.

Microwave signals propagate in one direction at a time, which means that two frequencies are necessary for two ways communication such as telephone communication. One frequency is reserved for transmission in one direction and other for transmission in other. Each frequency requires its own transmitter and receiver. Today, both pieces of equipment usually are combined in a single piece of equipment called transceiver, which allows a single antenna to serve both frequencies and functions.

Terrestrial microwave systems are typically used when using cabling is very costly and difficult to set.

Satellite Communication

Satellite transmission is much like line of sight microwave transmission in which one of the stations is a satellite orbiting the earth. The principle is the same as terrestrial microwave, with a satellite acting as a super-tall antenna and repeater. Although in satellite transmission signals must still travel in straight lines, the limitations imposed on distance by the curvature of the earth are reduced. In this way, satellite relays allow microwave signals to span continents and ocean with a single bounce.

Satellite microwave can provide transmission capability to and from any location on earth, no mater how remote. This advantage makes high quality communication available to undeveloped parts of the world without requiring a huge investment in ground based infrastructure. Satellite themselves are extremely expensive, of course, but leasing time or frequencies on one can be relatively cheap.

Infrared Transmission

Infrared media uses infrared light to transmit signals. LEDs transmit the signals, and photodiodes receive the signals. The remote control we use for television, VCR and CD player use infrared technology to send and receive signals.

Because infrared signals are in high frequency range, they have good throughput. Infrared signals do have a downside; the signals cannot penetrate walls or other objects, and they are diluted by strong light sources.

Transmission Impairments:

With any communication system, there is a high possibility that the signal that is received will differ from the signal that is transmitted as a result of various transmission impairments. For analog signals, these impairments introduce various random modifications that degrade the signal quality. For digital signals, bit errors are introduced: A binary 1 is transformed into a binary 0, and vice versa.

The most significant impairments are the following:

Noise

Noise refers to any unwanted signal. For any data transmission event, the received signal will consist of the transmitted signal, modified by the various distortions imposed by the transmission system, plus additional unwanted signals that are inserted somewhere between transmission and reception; the latter, undesired signals are referred to as noise-a major limiting factor in communications system performance.

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COMPUTER SAFETY AND ERGONOMICS

Meaning and importance of computer safety and ergonomics

Ergonomics is the science of adapting the job and/or the equipment and the human to each other for optimal safety and productivity. In basic language, ergonomics is the study of fitting the job to the worker rather than the worker to the job.

Computer ergonomics therefore means the designing machines, tools, and work environments to best accommodate human performance and behaviour. It aims to improve the practicality, efficiency, and safety of a person working with computer devices.

The use of computers has greatly increased over the last few decades. People now use computers and keyboards as a daily way of communicating, working, and even for entertainment. A condition known as Repetitive Strain Injury (RSI) has now been recognized as a result of the repetitive motion of typing and sitting in a fixed position (i.e. at a desk for eight hours). This can cause significant injury and pain to the arms, elbows, fingers, and wrists. This condition is extremely painful and can affect everyone from sedentary people to those who are active and physically fit.

Preventing RSI

  • Taking regular breaks from working at your computer – a few minutes at least once an hour
  • Alternating work tasks
  • Regular stretching to relax your body
  • Use equipment such as footrests, wrist rests and document holders if need be
  • Keeping your mouse and keyboard at the same level
  • Avoid gripping your mouse too tightly. You should hold the mouse lightly and click gently
  • Familiarize yourself with keyboard shortcuts for applications you regularly use (to avoid overusing the mouse)
  • Place your document at about the same height as the computer screen and make sure it’s close enough to the screen so you don’t have to look back and forth
  • Adjust you chair so the bottom of your feet reach and rest comfortable on the floor and the back of your knees are slightly higher than the chairs’s seat.
  • Adjust your screen to your height. The screen’s top viewing line should be no higher than your eyes and 18 – 24 inches from our face.
  • Position your keyboard properly. It should be placed on a lower-than-normal work surface in order to keep the arms in a downward position and not interfere with the blood flow to the hands and fingers. Forearms should be parallel to the floor and wrist in line with the forearm.
  • Organize your workstation so everything you need is within comfortable reach

Eyestrain

Another safety concerns resulting from use of computers is eyestrain.

Most computer-related eyestrain is caused by improper lighting. While you may not be able to do much about the overhead lighting, you can take these steps to minimize eyestrain:

  • Exercising the eyes by periodically focusing on objects at varying distances
  • Blinking regularly
  • Keeping the air around you moist – for example using plants, open pans of water or a humidifier (spider plants are said to be particularly good for this and removing chemical vapours from the air)
  • Adjusting the screen height / seating so that when sitting comfortably your eyes are in line with the top of the monitor screen
  • Adjusting the brightness control on your monitor for comfort
  • Adjusting the contrast on your monitor to make the characters distinct from the background
  • Adjusting the refresh rate of your monitor to stop it flickering
  • Positioning monitors to avoid glare (e.g. not directly in front of windows)
  • Keeping your monitor clean
  • Keeping the screen and document holder (if you use one) at the same distance from your eyes
  • Servicing, repairing or replacing monitors that flicker or have inadequate clarity
  • Regular eye testing

It is also important to have your workstation set up correctly or use ergonomically designed gadgets.

Monitors should:

  • Rotate, tilt and elevate – if not use an adjustable stand, books or blocks to adjust the height
  • Be positioned so the top line of the monitor is no higher than your eyes or no lower than 20° below the horizon of your eyes or field of vision
  • Be at the same level and beside the document holder if you use one
  • Be between 18 to 24 inches away from your face

Ergonomic Keyboards should:

  • Be detachable and adjustable (with legs to adjust angle)
  • Allow your forearms to be parallel to the floor without raising your elbows
  • Allow your wrists to be in line with your forearms so your wrists does not need to be flexed up or down
  • Include enough space to rest your wrists or should include a padded detachable wrist rest (or you can use a separate gel wrist rest which should be at least 50 mm deep)
  • Be placed directly in front of the monitor and at the same height as the mouse, track ball or touch pad

Ergonomic mouse should have:

  • The shape and size of the mouse should fit comfortably in the hand.
  • You should have the ability to hold the mouse in a neutral position, i.e., your hand should not be bent at any awkward position.
  • The mouse should be placed in such a way so that it can be used with your upper arm comfortably relaxed, and as near your body as possible, and without you having to reach towards the side or forwards for it.

Ergonomic Chairs should:

  • Support the back – and have a vertically adjustable independent back rest that returns to its original position and has tilt adjustment to support the lower back
  • Allow chair height to be adjusted from a sitting position
  • Be adjusted so the back crease of the knee is slightly higher than the pan of the chair (use a suitable footrest where necessary)
  • Be supported by a five prong caster base
  • Have removable and adjustable armrests
  • Have a contoured seat with breathable fabric and rounded edges to distribute the weight and should be adjustable to allow the seat pan to tilt forward or back

Ergonomic Tables and desks should:

  • Provide sufficient leg room and preferably be height adjustable
  • Have enough room to support the computer equipment and space for documents
  • Be at least 900 mm deep
  • Have rounded corners and edges

Computer Hardware Safety (check)

A phenomenal amount of information now resides on computers. Individual computers as well as computers on networks contain billions of pages of text, graphics, and other sources of information. Without safeguards, this information is vulnerable to misuse or theft.

Hardware security protects the machine and peripheral hardware from theft and from electronic intrusion and damage. The following are some of the measures to ensure hardware security:

  1. Physical Security
  • Physical on-site security can be provided by confining mission-critical computers like servers to a locked room, and restricting access to only those who are authorized.
  • Securing the physical perimeters of the room where the computer systems is kept is also necessary.
  • Ensuring only a single entrance is used to the computer room
  • Use of a strong lock on the door
  • Control access to the computer room using measures like:
    • access monitoring through badge-based entry
    • security guard at the building entrance,
    • Restriction of
    • unscheduled visits,
    • Surveillance cameras around the building and at each entrance.
    • Access monitoring through biometric devices like fingerprint readers, voice recognition systems and iris readers
  1. Fire Protection
  • Smoke detectors are usually installed to provide early warning of a developing fire by detecting particles generated by smoldering components prior to the development of flame. This allows investigation, interruption of power, and manual fire suppression using hand held fire extinguishers before the fire grows to a large size.
  • Hand-held fire extinguishers should be within close reach of the computers
  • Automatic fire sprinkler system is often provided to control a full scale fire if it develops.
  • Various materials within computer rooms can enhance the magnitude of fires. Create a non-combustible environment to decrease risk of fire and help ensure that if a fire does begin it will not spread quickly. If furnishings are necessary in the computer area, guarantee they are made of non-combustible materials. Also, try to keep papers outside of the computer room as they would quickly amplify any fire that begins within the space.
  • Perform regular testing on the safety equipment. For example, check the gauges of the fire extinguishers to see whether they need to be recharged. Re-train staff often on how to properly use the extinguishers and bring in professionals to ensure the devices are still in working order.
  • Ensure that there is a plan in place for staff to follow if there is a fire. Perform fire drills to keep the plan fresh in the minds of employees.

Computer software safety

  1. Use only genuine software
  2. Install antivirus software on your computer
  3. Keep your antivirus software updated.
  4. If you have an antivirus software you should have a scan at least once a day on your computer so that the software can remove viruses
  5. Don’t open any e-mails if you don’t know who sent them.
  6. Never open email attachments unless you know with certainty that the attachment is something you expected and want to receive.
  7. Install or turn on the firewall to protect your computer against automatic network virus attacks.

Data Safety/Security

Data security is the practice of keeping data protected from corruption and unauthorized access. The focus behind data security is to ensure privacy while protecting personal or corporate data.

Data could be anything of interest that can be read or otherwise interpreted in human form.

The unauthorized access of this data could lead to numerous problems for both organizations and individual. Having your bank account details stolen is just as damaging as the system administrator who has had client information stolen from the database.

There has been a huge emphasis on data security as of late, largely because of the internet. There are a number of options for ensuring safety of your data and they include:

Encryption

Encryption has become a critical security feature for thriving networks and active home users alike. This security mechanism uses mathematical schemes and algorithms to scramble data into unreadable text. It can only by decoded or decrypted by the party that possesses the associated key.

Strong User Authentication

Authentication is another part of data security that we encounter with everyday computer usage. Just think about when you log into your email or blog account. That single sign-on process is a form of authentication that allows you to log into applications, files, folders and even an entire computer system. Once logged in, you have various given privileges until logging out. Some systems will cancel a session if your machine has been idle for a certain amount of time, requiring that you prove authentication once again to re-enter.

Use of Passwords

Sensitive data should always be protected by a password which should be chosen wisely. Unfortunately, many users choose weak passwords that provide little protection against the experienced hacker. A strong password contains more than eight characters which are a combination of letters (both upper case and lower case), symbols or numbers.

Backup Solutions

Data security wouldn’t be complete without a solution to backup your critical information. Though it may appear secure while confined away in a machine, there is always a chance that your data can be compromised. You could suddenly be hit with a malware infection where a virus destroys all of your files or a hacker can get access to your computer and corrupt/ steal data your data. If all else fails, a reliable backup solution will allow you to restore your data instead of starting completely from scratch. It is also important that you also keep a copy of your backup solution off-site in a secure location.

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COMPUTER PERSONNEL

Attributes/ Skills necessary for Computer Personnel

1. Analytical skills

These will enable systems analysts to understand the organization and its functions, which helps him/her to identify opportunities and to analyze and solve problems.

2. Technical skills

Will help systems analysts understand the potential and the limitations of information technology. The systems analyst must be able to work with various programming languages, operating systems, and computer hardware platforms.

3. Management skills

Will help systems analysts manage projects, resources, risk, and change.

4. Interpersonal skills

Will help systems analysts work with end users as well as with analysts, programmers, and other systems professionals.

 Responsibilities/Roles of a Computer Programmer

  • The main role of computer programmer the development of programs.
  • Programmers also correct errors by making appropriate changes and then rechecking the program to ensure that the desired results are produced.
  • Another specific duty of a computer programmer is to perform monitoring tasks to ensure that the programs which they develop work as they are supposed to. This is done by reviewing programs on a frequent basis and making adjustments as are necessary to ensure the proper working of a computer program.
  • The computer programmer may also be the individual who is responsible for providing technical support to those who use the computer programs developed by the individual and his/her company.
  • Programmers compile and write documentation of program development and subsequent revisions, inserting comments in the coded instructions so others can understand the program.
  • Consult with managerial, engineering, and technical personnel to clarify program intent, identify problems, and suggest changes.
  • Perform or direct revision, repair, or expansion of existing programs to increase operating efficiency or adapt to new requirements.

Responsibilities/Roles of System Analyst (check)

  1. Interact with the customers to know their requirements
  2. Act as liaisons between vendors and the organization they represent.
  3. They are responsible for feasibility studies of a computer system before making recommendations to senior management.
  4. Perform system testing.
  5. Deploy the completed system.
  6. Research, plan, install, configure, troubleshoot, maintain and upgrade operating systems.
  7. Research, plan, install, configure, troubleshoot, maintain and upgrade hardware and software interfaces with the operating system.
  8. Research and recommend hardware and software development, purchase, and use.
  9. Troubleshoot and resolve hardware, software, and connectivity problems, including user access and component configuration.
  10. Write and maintain system documentation.

Responsibilities/Roles of a System Designer

  • work with analysts on the feasibility of a conceptual design by taking technical specifications prepared by the analyst and designing system components to meet the set requirements
  • draw up detailed design documentation including charts and diagrams that indicate the various components involved
  • prepare instructions for programmer implementation
  • talk with other team members (analysts and programmers) to ensure functionality according to systems specifications, and develop solutions as problems or issues arise
  • design monitoring and performance measurement processes.
  • The system designer is also responsible for writing the test plans and co-ordinating with a team of user and system testers to ensure that the system is thoroughly tested.

Responsibilities/Roles of a System Administrator

  • Create new users
  • Resetting user passwords
  • Lock/unlock user accounts
  • Monitor server security
  • Install, support, maintain and monitor servers or other computer systems
  • Plan for and respond to service outages and other problems.
  • Install software
  • Create a backup and recover policy
  • Monitor network communication
  • Update system as soon as new version of OS and application software comes out
  • Implement the policies for the use of the computer system and network
  • Setup security policies for users. A system admin must have a strong grasp of computer security (e.g. firewalls and intrusion detection systems).
  • Monitor system performance

Responsibilities/Roles of the Network Administrator

  • Designing and planning the network by making choices about network structure and networking protocols
  • Setting up the network
  • Maintaining the network
  • Expanding the network
  • making resources available on the network by:
    • managing user accounts
    • sharing directories
    • setting up shared printers
  • keeping the network running smoothly by:
    • monitoring activity on the network and tuning performance
    • troubleshooting the network

Responsibilities/Roles of a Database Administrator (check)

A database administrator’s responsibilities can include the following tasks:[6]

  • Installing and upgrading the database server and application tools
  • Allocating system storage and planning future storage requirements for the database system
  • Modifying the database structure, as necessary, from information given by application developers
  • Enrolling users and maintaining system security
  • Ensuring compliance with database vendor license agreement
  • Controlling and monitoring user access to the database
  • Monitoring and optimizing the performance of the database
  • Planning for backup and recovery of database information
  • Maintaining archived data
  • Backup|Backing up and restoring databases
  • Contacting database vendor for technical support
  • Generating various reports by querying from database as per need.
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HARDWARE, SOFTWARE SELECTION AND ACQUISITION

Meaning of hardware/ software selection and acquisition (check)

Hardware and software acquisition is the act of coming into possession of hardware and software solutions in an organization. It can also be referred to as gaining, procuring, securing or obtaining hardware and software. Includes but is not limited to buying, renting and leasing as well as accepting as a gift or donation.

Selection on the other hand refers to choosing the best solution from several alternatives.

Importance of hardware/software selection and acquisition (check)

The process of hardware/software selection and acquisition is important because it ensures that the organization acquires hardware/software:

  • At the best possible price
  • In the right quality
  • At the right time
  • From the right source
  • That meets the users needs

 Factors considered in hardware and software selection and acquisition

 Hardware Selection Criteria

  • Hardware must support current software as well as software planned for procurement in future
  • Hardware must be compatible with existing or planned systems
  • Hardware must be upgradeable and expandable to meet the future needs
  • Hardware cost must be within the budget
  • Hardware must be reliable
  • Hardware vendor should be of high reputation

Software Selection Criteria

  • Software must be compatible with current and future hardware needs
  • Software must be user friendly
  • Software vendor should provide user training
  • Software vendor should be of high reputation
  • Software vendor should provide user manuals

 Software Procurement Procedures

1. Software Specification

The first stage in procurement is to identify an organization’s need for a service or a product. Once a requirement has been identified, the specification is prepared. A specification defines the requirement in terms of performance, quality, quantity and timescales.

2. Determine Your Evaluation Criteria

To start the RFP process, determine what criterion you are going to evaluate the vendors proposals on and establish the weight each criterion will hold in relation to the others. Common criteria include experience, team strength, project understanding, differential advantage, and price. Evaluations based on established criterion will help to eliminate any situational bias that may occur.

An example of an evaluation criterion is shown in the table below:

The above is called a qualitative evaluation criterion as it is an assessment that partly depends on perception. The second part of evaluation is quantitative as it measures relative costs amongst the suppliers. An example of elements of cost analysis is shown below:

  1. Request for proposal (RFP)

 The RFP is a solicitation process in which vendors are asked to submit sealed bids on a specific software. The RFP specifies what the buyer needs, how the buyer is going to evaluate the bids, and all the terms and conditions surrounding the subsequent contract. The RFP process brings structure to the procurement decision and allows the risks and benefits to be identified in advance.

An RFP typically involves more than a request for the price. Other requested information may include basic corporate information and history, financial information (can the company deliver without risk of bankruptcy), technical capability, product information and customer references that can be checked to determine a company’s suitability.

  1. Briefing conference

Often suppliers seek clarification or additional information. To ensure that no vendor is disadvantaged and that the same information is passed, a briefing conference is organized. This will be a formal session to answer questions from potential suppliers.

  1. Proposal Evaluation

It is advisable to perform evaluation in three stages.

The first stage is to eliminate suppliers/vendors who do not meet the most basic requirements leaving only those who qualify for more in-depth evaluation.

The second stage will be more comprehensive evaluation to determine a short-list of three or four suppliers. Finally, references may be taken up for short-listed potential suppliers with their existing clients. These references are useful as they provide an evaluation of the proposed software in a live environment.

References are done to determine overall satisfaction that existing clients have with the short-listed suppliers. The issues that should be addressed are:

  • Ease of installation
  • Ease of use
  • Training
  • Quality of documentation
  • System efficiency
  1. Selecting a vendor

After client references, the winning vendor is selected based on the evaluation and invited for contract negotiation.

  1. Contract Negotiation and signing

The negotiation process is the final stage of procurement. The main objective of contract negotiation is to work out a fair deal that will avoid litigation. It assumes that all the   terms of the supplier are negotiable.

It is advisable to use a lawyer to revise the standard supplier agreement so as to develop specific issues relevant to the contract.

optional

The contract should cover the following:

  • Currently purchased software and ‘optional’ software, documentation, manuals and source code (if applicable)
  • If the software is being licensed, is the license non-exclusive and non-transferable?
  • Does the contract cover all the future enhancements, updates and additions?
  • How will the supplier resolve compatibility?

Payment

The contract should take care of payment issues especially if the supplier requires non-refundable deposit

Delivery

The contract should specify how software will be delivered, how and when will   software be tested for performance. Appropriate insurance should be taken out to cover for any potential loss

Acceptance testing

The key to successful acceptance testing is to develop, in advance, an objective method of defining compliance/non-compliance. This method should involve definition of technical standards against which the software can be measured. Some critical areas that can be incorporated into the performance specification are the degree to which software complies to technical requirements in RFP and how the client will attain redress if the test is not passed.

Deliverables

The agreement should specify clearly the number of copies of the software that the supplier will deliver and the media of delivery. The type of documentation accompanying delivery should also be specified together with the number of documentation manuals.

Warranty

Warranty is a period the supplier undertakes to remedy any faults found in the software without asking for a support contract. After this period the client must take out a support contract or pay for services. Warranty is negotiable and the buyer should tie it to product specification.

Term and termination

The contract should define how long the contract will remain in force (term) and how it can be terminated

Hardware Procurement Procedures

1. Hardware specification

In specifying hardware capacity, also called sizing, some of the most important features are: speed, storage capacity, connectivity and communication facilities.

2. Processor speed

The processor speed, measured in Hertz, defines the speed at which the computer performs specific instructions. The  faster the computer can perform an instruction, the faster its response to users. Processor speeds are significant in a multi-user environment.

3. Storage capacity/memory size

The size of memory, measured in bytes, will determine the size and the number of programs that the computer will run. The speed of the computer is very important if the computer is expected to make many programs available at the same time. The memory size must be adequate to support such processing environment. Storage capacity which is also measured in bytes, determines the amount of data and information that a computer can hold at a given time.

4. Connectivity

Connectivity measures the number of input and output devices that can be connected to a computer. An organization should specify the total number of devices as these will affect the size of working storage required. A specific hardware model will also impose the maximum number of devices that can be connected.

5. Communication facilities

Computers can provide different communication facilities. If necessary the facilities ought to be specified at the outset and the requirements defined. If these are not specified, there may be need to upgrade the computer by inserting cards at a later stage.

6. Request for proposal (as above)

7. Proposal Evaluation (as above)

Evaluation is done in three stages.

The first stage is to eliminate suppliers/vendors who do not meet the most basic requirements leaving only those who qualify for more in-depth evaluation.

The second stage will be more comprehensive evaluation to determine a short-list of three or four suppliers. Finally, references may be taken up for short-listed potential suppliers with their existing clients. These references are useful as they provide an evaluation of the proposed hardware in a live environment.

8. Selecting a vendor (as above)

9. Contract scope and negotiation

After selection of a suitable supplier, contract negotiation will commence. There are legal considerations which should be handled by a legal counsel. However the following matters which are of general nature should also be considered:

1. Delivery

It should be specified clearly who meets the cost of delivery and who will be responsible if the hardware is damaged while on transit, between the buyer and the seller. In most cases the supplier takes out insurance for this purpose and may add this cost to the overall price of the hardware. Alternatively an organization may wish to avoid this cost by accepting responsibility for delivery from the supplier’s premises.

2. Warranty period

Warranty period is a duration in which the supplier undertakes to replace or repair equipment in the event of a breakdown. It should be specified clearly and it should commence at the time of successful installation rather than delivery.

3. Support considerations

Every computer system requires maintenance for both hardware and software which is traditionally provided by the supplier. The extent of support to be provided should be specified.

4. Installation

Installation of hardware, especially for large computer systems, is often the responsibility of the supplier. However the installation of micro-computers can be undertaken by the user. It is important to specify who will be responsible. At the end of a successful installation the supplier will issue an installation certificate, whish in effect says that a warranty period has commenced.

5. Training

The computer supplier frequently provides training to staff of an organisation to enable them use the computer. This form of training is, however, limited. An organisation should provide additional funds for further training.

Methods of hardware and software acquisition and selection (check)

The four methods of acquiring and / or financing the computer costs are;

  • Rental
  • Purchasing
  • Leasing
  • Using Bureaus

 

 1.       Renting a computer

This is a very common arrangement of acquiring computer facilities. The computer facilities are acquired and installed for use within the aspiring user’s premises at fixed periodic charges, e.g. monthly charges, payable to the vendor. Most agreements have a minimum rental period, such as 90 days.

Advantages:

  • Tax allowances are available.
  • There is no large initial capital expenditure.
  • The effects of technological changes are reduced, because during the agreement period, the charges are fixed hence inflation and maintenance are taken by the manufacturer and obsolete equipments can be returned to him.
  • The user has more flexibility to change the equipment configuration.

Disadvantages

  • This method of acquiring the computer and its related facilities is usually expensive in the long term, that is with time more computer varities and related facilities may be in market hence prices fall, but the rental charges remain fixed.
  • The computer and the related facilities remain the assets of the manufacturer and hence can not be used by the renting company as a security e.g. while seeking loan facilities.
  • In breach of the rental agreement , the computer and the related facilities may be repossessed by the manufacturer.
  • The renting company usually pays more for any extra work done by the computer and its facilities, that was not covered in the rental agreement.
  • Productivity of machine comes down with time but rental charges remain the same.

 

2.        Purchasing a computer

The buyer pays the supplier an amount equivalent to the computer and related facility’s value and the purchasing company owns the computer and the related facilities.

The payment can be in cash, through bank savings, loan arrangement or hire purchase arrangements. Whether it is straight purchase or through e.g. hire purchase the buying company gets the ownership of the facilities including the computer though in hire-purchase arrangement the ownership shall be limited to the extent payments are made. The computer and the related facilities therefore become full property of the buying company after all the installment payments are made.

Advantages:

  • The computer and the related facilities become the assets of the buying company.
  • It may be cheaper in the long term with tax advantages.
  • Frequent expenditure is not expected, where the manufacturer enters maintenance agreement with the buying company.
  • The company can decide to sell the computer and/ or related facilities to generate cash, which will depend on the market value of the facility to be sold.
  • Since the company owns the computer and the related facilities, there are no extra charges for additional work done, as in renting.

Disadvantages

  • In long term the computer and the related facilities may become obsolege, hence the organization suffers the loss, due to advancement in technology, Note that computer technology, advances fast generally, though it is dependent on the manufacturers of a particular computer family and amount of research.
  • An organization acquires the computer and its related facilities in order to carry out its data processing tasks, which keep on changing. A good facility therefore will be that facility which is flexible to adapt to the current work load of the organization, it is a common situation where the work load is beyond or much below the computer configuration’s capabilities.
  • There is large initial capital outlay but the returns are usually slow.
  • Capital committed in purchasing the computer and its related facilities may be spent on other higher returning investments for the organization.
  • Several other competing investment opportunities would have to be forgone in making the big cash outflow for purchasing the computer. The outflow would also reduce the company’s liquidity greatly. If use is made of loan facilities that would represent a liability in the balance sheet as also impose the burden of loan repayment and interest.

 

3.        Leasing a computer

The leasing company (Lessor), instals the computer and its facilities in the user’s (lessee’s) premises. The lessee then pays leasing charges to the lessor, who acquires the computer and its related facilities from the manufacturer and meets all the payments of the equipments values.

Leasing contracts are similar to rental contracts but usually for longer periods than those of renting. Leasing contract charges are low and renewable even at lower rates as compared to rental agreements.

Advantages

  • Leasing agreements charges are lower than the rental charges, and the contracts are renewable even at lower rates unlike rental agreements.
  • In leasing, the extra work load for the computer system is not charged for by the lessor.
  • It does not require heavy initial investment.
  • Lease expenditure being a revenue expense may be charged to the profit and loss account.
  • Maintenance charges are included in the lease charges.
  • Lease charges generally decline after a specified period.

Disadvantages

  • Fixed charges are to be met.
  • The computer and the related facilities may be repossessed by the lessor, in case the leasing contract is breached.
  • The computer and the related facilities remain the assets of the lessor.
  • Maintenance contracts may not be a guarantee, after a certain period of time, though the lessee may suffer inflexibility within the lease time e.g. when the equipments fail to adapt to the functional environments of the organisation. This aspect is, therefore, worth to clarify during the signing of the leasing contract between the lessee and the lessor. Note that maintenance contract is usually agreed on by the manufacturer for the leased equipment.
  • In this arrangement of acquiring the computer and its facilities, the lessee has got no choice over such facilities, because the lessor acquires such facilities from the manufacturer of his choice.
  • The primary period for leasing is usually much longer than the renting period.

 

4. Using a bureaus

The methods of acquiring the computer equipments discussed so far i.e rental, purchasing, or leasing are used to acquire ‘in-house’ computer equipments that is the computer equipment is installed within the aspiring organization’s premises.

A bureau is an organization which renders computer services to, other companies which depend on such services, its clients. Computer bureaus can be companies, manufacturers, or users, with extra time to hire out, who work an aim of rendering services to the other companies.

Computer bureaus renders a wider cross section of the processing tasks for other organizations on either continuously or on demand basis.

Some of such services are:

  • System analysis and design.
  • Developing computer programs.
  • Computer time hire out, and do-it-yourself.
  • Advice and consultancy.

Notes:

The bureaus may undertake a full service to a given company, in the computer related services. Basically, all bureaus offer a wider cross section of the data processing services, though others may specialize on the industry, processing tasks or application type they deal with.

 Advantages

  • A company that is considering acquiring a computer may find it extremely beneficial to use a bureau because:
  • It can evaluate the type of computer it is interested in.
  • It can test and develop its programs prior to the delivery of its own computer.
  • Its staff will become familiar with the requirements of a computer system.
  • The major benefit of using data centre is that the user pays only for the information systems development and D.P. services that he needs. Installing in-house computer and employing staff of D.P. professionals creates fixed costs such as machine cost, rent, depreciation, salaries, etc.
  • Many companies cannot justify the installation of an in-house computer on cost benefit grounds and the use of a bureau does not require a high capital outlay. Thus the computing services can be availed using a data centre and the organisation is not having sufficient finance for the installation of an in-house computer.
  • Some computer users find it convenient to employ a bureau to cope with peak loads arising, for example, from seasonal variation in sales. Also if the organisation has insufficient volume of work to justify the installation of a computer, it can go for data centre.
  • A bureau’s computer may be used in the event of a breakdown of an in-house machine.
  • Enable the data processing to be done by the people who have the expertise.
  • Obtain advice on all aspects of systems development and operation.
  • Enable the client to obtain the user up-to-date computer technology, specialised equipment, and programs.
  • However, there are also time-sharing vendors who provide for a fee the usage of central computer and online file storage to users who obtain access through remote terminals and telecommunication lines. Time-sharing vendors also generally offer a large number of specialized programs many of which the user may find to be strikingly applicable and useful.
  • It avoids the responsibility of operating an in-house computer, i.e., it eliminates the personnel and management problems caused by the employment of a group of highly paid technical professionals in a rapidly changing and highly technical field of computer.

Disadvantages:

  • The users of the bureau services have got no control over their jobs once they are submitted to the bureau.
  • Periodic audit is necessary, because transportation of data and/or information from the organization to the bureau’s premises or vice versa, may pose problems e.g. fraud.
  • Control by individual companies is difficult because processing goes on at a remote location.
  • Documentation strictly adhered to, to ease the understanding of the systems, whose developers might not be available during the running of the systems. This is especially in a situation where the bureau develops and implements the systems.
  • Confidential information’s security is at risk and the cost of using the bureau services should be carefully weighed out against the cost of using an in-house set up as an alternative. In most cases, the use of bureau services may be expensive, especially in the long term.
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INTRODUCTION TO COMPUTERS

Historical evolution of computers

Abacus 500B.C

The abacus, which emerged about 5,000 years ago in Asia Minor and is still in use today, may be considered the first computer. This device allows users to make computations using a system of sliding beads arranged on a rack. Early merchants used the abacus to keep trading transactions. But as the use of paper and pencil spread, particularly in Europe, the abacus lost its importance. It took nearly 12 centuries, however, for the next significant advance in computing devices to emerge.

Napier’s Bones

The next significant development after the abacus came in 1617 when John Napier, a Scottish mathematician, invented the Napier bones. These were simply rods on which numbers were marketed. These numbers enable the user to easily work out the answers to a restricted set of the multiplication tables.

The numbers to be multiplied are positioned on the top row and the left column. Answer is obtained at the interoperation of these two. This method, pioneered by Napier, is still used as a curiosity in Math lessons at some local schools.

Slide rule 1632 William Oughtred

The invention of both logarithms and Napier’s bones led to the invention of a device termed Slide Rule by William Oughtred. This device makes use of a cursor, which is moved up and down various scales to perform multiplication and division using the principles of Logarithms. Thus, the device is equivalent to today pocket calculator.

Blaise Pascal (1623 – 1662)

The idea of using machines to solve mathematical problems can be traced at least as far as the early 17th century. Mathematicians who designed and implemented calculators that were capable of addition, subtraction, multiplication, and division included  Blaise Pascal.

In 1642, at the age of eighteen Blaise Pascal invented a mechanical calculator; first called Arithmetic Machine, Pascal’s Calculator and later Pascaline, it could add and subtract directly and multiply and divide by repetition.

This machine involved a set of wheels, each with the numbers zero through to nine on them. The wheels were connected with gears, so that a complete turn of one wheel would move the wheel next to it through one-tenth of a turn. This machine was of great use to his father—a judge in the taxation court—and to others involved in calculations. Although expensive to make and difficult to operate, Pascal’s calculating machine was an essential step in the subsequent development of calculators and computers.

Jacquard Loom 1801

The Jacquard Loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, that has holes punched in pasteboard, each row of which corresponds to one row of the design. Multiple rows of holes are punched on each card and the many cards that compose the design of the textile are strung together in order.

The Jacquard loom was the first machine to use punch cards to control a sequence of operations. Although it did no computation based on them, it is considered an important step in the history of computing hardware. The ability to change the pattern of the loom’s weave by simply changing cards was an important conceptual precursor to the development of computer programming. Specifically, Charles Babbage planned to use cards to store programs in his Analytical engine.

Charles Babbage (1791-1871)

The real beginnings of computers as we know them today, however, lay with an English mathematics professor, Charles Babbage (1791-1871). Frustrated at the many errors he found while examining calculations for the Royal Astronomical Society, Babbage declared, “I wish to God these calculations had been performed by steam!” With those words, the automation of computers had begun. By 1812, Babbage noticed a natural harmony between machines and mathematics: machines were best at performing tasks repeatedly without mistake; while mathematics, particularly the production of mathematic tables, often required the simple repetition of steps. The problem centered on applying the ability of machines to the needs of mathematics. Babbage’s first attempt at solving this problem was in 1822 when he proposed a machine to perform differential equations, called a Difference Engine. Powered by steam and large as a locomotive, the machine would have a stored program and could perform calculations and print the results automatically. After working on the Difference Engine for 10 years, Babbage was suddenly inspired to begin work on the first general-purpose computer, which he called the Analytical Engine.

Turing’s Colossus

Turing undertook the construction work of a special-purpose electronic machine. In January 1943, he headed up a team of scientists whose specific goal was to try to break Enigma code. To do so, the team developed a computer – called the “Colossus” comprising 1,500 vacuum tubes. The Colossus machines were the world’s first programmable, digital, electronic, computing devices. They used vacuum tubes (thermionic valves) to perform the calculations.

Computer Generations

The history of computer development is often referred to in reference to the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, and more powerful and more efficient and reliable devices.

First Generation (1945-1956)

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. 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, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.

The UNIVAC and ENIAC computers are examples of first-generation computing devices storage.

Second Generation Computers (1956-1963)

Transistors replaced vacuum tubes and ushered in the second generation of computers. 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.

Third Generation Computers (1964-1971)

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.

Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.

Fourth Generation (1971-Present)

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, 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.

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 GUIs, the mouse and handheld devices.

Fifth Generation (Present and Beyond)

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. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

Computer hardware components 

If you use a desktop computer, you might already know that there isn’t any single part called the “computer.” A computer is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. (Software, on the other hand, refers to the instructions, or programs, that tell the hardware what to do.)

The illustration below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.

The system unit, sometimes called the chassis, is a box-like case housing the electronic components of a computer that are used to process data. System unit components include the processor, memory module, cards, ports, and connectors. Many of the system unit’s components reside on a circuit board called the motherboard.

The most important of these components is the central processing unit (CPU), or microprocessor or just processor. Other components include memory module (RAM), cards, ports, and connectors.

Almost every other part of your computer connects to the system unit using cables. The cables plug into specific ports (openings), typically on the back of the system unit. Hardware that is not part of the system unit is sometimes called peripheral devices.

Describe the components in the system unit

Describe the types of expansion slots and cards in the system unit

An expansion slot is an opening, or socket, where you can insert a circuit board into the motherboard. These circuit boards – called cards, expansion cards, boards, expansion boards, adapters, adapter cards, interface cards, add-ins, or add-ons — add new devices or capabilities to the computer. Four types of expansion cards found in most computers are a video card, a sound card, a network interface card, and a modem card.

A video card converts computer output into a video signal that is sent through a cable to the monitor, which displays an image. A sound card enhances the sound-generating capabilities of a personal computer by allowing sound to be input through a microphone and output through speakers.

A network interface card (NIC) is a communications device that allows the computer to communicate via a network. A modem card is a communications device that enables computers to communicate via telephone lines or other means. Many of today’s computers support Plug and Play, a capability with which the computer automatically can configure expansion boards and other devices as you install them.

Notebook and other portable computers have a special type of expansion slot used for installing a PC Card, which is a thin credit card-sized device that adds memory, disk drives, sound, fax/modem, and communications capabilities to a mobile computer.

explain the difference between a serial, a parallel, and a USB port

A cable often attaches external devices to the system unit. A port is the interface, or point of attachment, to the system unit. Ports have different types of connectors, which are used to join a cable to a device. Male connectors have one or more exposed pins, while female connectors have matching holes to accept the pins. Most computers have three types of ports: serial, parallel, and USB. A serial port is a type of interface that connects a device to the system unit by transmitting data only one bit at a time. Serial ports usually connect devices that do not require fast data transmission rates, such as a mouse, keyboard, or modem. A parallel port is an interface that connects devices by transferring more than one bit at a time. Many printers connect to the system unit using a parallel port. A universal serial bus (USB) port can connect up to 127 different peripheral devices with a single connector type, greatly simplifying the process of attaching devices to a personal computer.

The central processing unit (CPU) is sometimes referred to simply as the central processor or the processor. The CPU is that portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer.

The CPU itself is an internal component of the computer. Modern CPUs are small and square and contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard.

Two typical components of a CPU are the following:

  • The arithmetic logic unit (ALU), which performs arithmetic and logical operations.
  • The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.
  • Memory (RAM). This is primary memory or the volatile memory

                   Computer Bus System (check)

The ALU, the control unit and the main memory unit must communicate to function properly. These components are linked through electrical pathways called buses. The bus is therefore an electrical path for signal to flow from point to point in a circuit. The purpose of buses is to reduce the number of “pathways” needed for communication between the components, by carrying out all communications over a single data channel. This is why the metaphor of a “data highway” is sometimes used.

The bus consists of three main parts:

1. Control bus (or command bus)

This is a unidirectional pathway for all timing and controlling functions of the CPU. The signals send through the control bus by the control unit regulates all other important functions of the CPU.

2. Address bus (or memory bus)

An address bus is a unidirectional pathway used to locate the storage (address) place in the memory of the data to be executed or an instruction to be decoded.

3. Data bus

A data bus is a bi-directional pathway where actual data transfer takes place. The diagram below shows how the CPU communicates with other devices using the bus system.

Describe how buses contribute to a computer’s processing speed(check)

Bits are transferred internally within the circuitry of the computer along electrical channels. Each channel, called a bus, allows various devices inside and attached to the system unit to communicate with each other. The bus width, or size of the bus, determines the number of bits that can be transferred at one time. The larger the bus width, the fewer number of transfer steps required and the faster the transfer of data. In most computers word size (the number of bits the CPU can process at a given time) is the same as the bus width. Every bus also has a clock speed. The higher the bus clock speed, the faster the transmission of data, which results in applications running faster. A computer has two basic types of buses. A system bus connects the CPU to main memory. An expansion bus allows the CPU to communicate with peripheral devices.

The diagram below shows the overall organization of the CPU and its relationship with other main components of the computer

A is   Input devices

B is ALU

C is Main memory

D is Secondary storage devices

E is Output Devices

Storage devices (include registers, flash memory) classify them as well and give the advantages and disadvantages of each

Storage devices

A computer storage device is any type of hardware that is used to record and store data. The most common type of storage device, which nearly all computers have, is a hard disk.

In modern day computers, storage devices can be found in many forms and can be classified based on many criterions. Of them, the very basic is; Primary storage, Secondary storage and Tertiary storage. Storage devices can be further classified based on the memory technology that they use, based on its data volatility etc

The following list gives a few classifications of memory devices.

  • Primary and Secondary and Tertiary Storage
  • Volatile and non-volatile storage
  • Read only and Writable storage
  • Random Access and  Sequential Access storage

The diagram below shows how the Primary, Secondary and Tertiary Storage are organised.

Primary storage

The primary storage devices are those which hold data and instructions that are required by processor to perform an operation. These storage devices are very high speed devices and the CPU can directly access it. The information in these devices is volatile in nature, that is the information in these devices is retained only while the computer system is on. As soon as the computer system is turned off the information stored in the computer’s main memory is lost. The primary memory devices are very costly and have limited space.

Types of Primary storage

  • The most commonly used primary memory medium is RAM (Random Access Memory). This memory is placed in a computer where the operating system, application programs and data in current use are kept so that they can be quickly reached by the computer’s processor. RAM is much faster to read from and to write to than the other kinds of storage in a computer. However, the data in RAM stays there only as long as your computer is running. When you turn the computer off, RAM loses its data. When you turn your computer on again, your operating system and the other files are once again loaded into RAM, usually from your hard disk.

RAM is small, both in terms of its physical size and in the amount of data it can hold. Computers with large amount of primary memory often perform faster simply because the CPU does not sit idle waiting for data to be retrieved from slower components like the hard disk.

RAM is of two types:  Static RAM (SRAM) and Dynamic RAM (DRAM). Dynamic random-access memory is a form of volatile memory which also requires the stored information to be periodically re-read and re-written (i.e. refreshed), otherwise it would vanish. Static random-access memory is a form of volatile memory similar to DRAM with the exception that it never needs to be refreshed as long as power is applied. It loses its content only if power is turned off.

  • Read only memory (ROM)

Every stored-program computer needs some form of non-volatile storage (that is, storage that retains its data when power is removed) to store the initial startup program (BIOS). This program runs when the computer is powered on or otherwise begins execution (a process known as bootstrapping, often abbreviated to “booting” or “booting up”). To achieve this read only memory (ROM) is used.

ROM is a type of primary storage device. Unlike a computer’s RAM, the data in ROM is not lost when the power is turned off. The ROM is sustained by a small long-life battery in the computer.

NOTE

BIOS is an acronym for basic input/output system, the built-in software that determines what a computer can do without accessing programs from a disk. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives and a number of miscellaneous functions.

The BIOS is typically placed in a ROM chip that comes with the computer (it is often called a ROM BIOS). This ensures that the BIOS will always be available and will not be damaged by disk failures. It also makes it possible for a computer to boot itself. Because RAM is faster than ROM, though, many computer manufacturers design systems so that the BIOS is copied from ROM to RAM each time the computer is booted. This is known as shadowing.

  • Cache

Processor cache memory also comes under primary storage devices. It is an intermediate stage between ultra-fast registers and much slower main memory. It’s introduced solely to increase performance of the computer. Most actively used information in the main memory is just duplicated in the cache memory, which is faster, but of much lesser capacity.  This memory is very small and of very high speed. It resides very close to the CPU. Retrieving data from cache takes a fraction of the time that it takes to access it from main memory.

  • Registers

In computer architecture, a processor register is a small amount of storage available on the CPU whose contents can be accessed more quickly than storage available elsewhere. Most modern computer architectures operate on the principle of moving data from main memory into registers, operating on them, and then moving the result back into main memory.

A register may hold a computer instruction , a storage address, or any kind of data. When the processor executes instructions, data is temporarily stored in registers, which are small local memory locations of 8, 16, 32 or 64 bits. Depending on the type of processor, the overall number of registers can vary from about ten to many hundreds.

A common property of computer programs is locality of reference: the same values are often accessed repeatedly; and holding these frequently used values in registers improves program execution performance.

Processor registers are considered a type of primary storage at the top of the memory hierarchy. They provide the fastest way for a CPU to access data.

Secondary Storage

Secondary Storage refers to non-volatile data storage which is not directly accessible by the CPU and only accessible via primary storage devices using I/O (Input/Output) channels or device drivers. Typical examples of Secondary Storage are hard disks, floppy disks, optical storage devices (such as CD, DVD drives) and flash memory (such as USB sticks /keys.)

Hard disk drive

Your computer’s hard disk drive stores information on a hard disk, a rigid platter or stack of platters with a magnetic surface. Because hard disks can hold massive amounts of information, they usually serve as your computer’s primary means of storage, holding almost all of your programs and files. The hard disk drive is normally located inside the system unit.

Advantages

  • Large storage capacity
  • Stores and retrieves data much faster than a floppy disk or CD-ROM
  • Data is not lost when you switch off the computer
  • Usually fixed inside the computer so cannot get mislaid.
  • Cheap on a cost per megabyte compared to other storage media.
  • Hard disks can be replaced and upgraded as necessary
  • Can have two hard disks in a machine, one can act as a mirror of the other and create a back up copy.

Disadvantages

  • Hard disks eventually fail which stops the computer from working.
  • Regular ‘head’ crashes can damage the surface of the disk, leading to loss of data in that sector.
  • The disk is fixed inside the computer and cannot easily be transferred to another computer.

Flash memory
Flash memory, also known as flash ROM or flash RAM, is nonvolatile memory that can be erased electronically and reprogrammed in units of memory called blocks consisting of multiple locations. It is a variation of electrically erasable programmable read-only memory (EEPROM) which, unlike flash memory, is erased and rewritten at the byte level, which is slower than flash memory updating.

Flash memory is often used to hold control code such as the basic input/output system (BIOS) in a personal computer. When BIOS needs to be changed (rewritten), the flash memory can be written to in block (rather than byte) sizes, making it easy to update. On the other hand, flash memory is not useful as RAM because RAM needs to be addressable at the byte (not the block) level.

Flash memory costs far less than EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid-state storage is needed. Examples of applications include digital audio players, digital cameras and mobile phones. Flash memory is also used in USB flash drives (thumb drives), which are used for general storage and transfer of data between computers. It has also gained some popularity in the gaming market, where it is often used instead of EEPROMs for game save data.

Flash memory gets its name because the microchip is organized so that a section of memory cells are erased in a single action or “flash.”

The main advantage of flash memory is how convenient it is. The device is very small and yet capable of holding hundreds of files. Another advantage is the fact that the device has no moving parts, allowing it to be carried easily without worry of wear and tear or losing data. Possibly the best advantage is the price. Flash drives cost roughly a quarter of the price of similar hard drives.

CD and DVD drives

Nearly all computers today come equipped with a CD or DVD drive, usually located on the front of the system unit. CD drives use lasers to read (retrieve) data from a CD, and many CD drives can also write (record) data onto CDs. If you have a recordable disk drive, you can store copies of your files on blank CDs. You can also use a CD drive to play music CDs on your computer.

Advantages
Information is fixed and cannot be changed or altered in any way. It is easily transportable and is compatible with any other PC or laptop . The data can also be easily destroyed simply by breaking or cutting the CD.

Disadvantages, are that the data (once created) cannot be changed or updated. It can easily be lost or stolen, It can also be damaged and rendered unusable quite easily. Holds less data than a DVD

A CD-ROM can hold up to 700MB (megabytes), while a DVD ROM can hold up to 4.7GB (gigabytes, one gigabyte = 1024, megabytes). CD-ROMs are slightly cheaper to manufacture.

DVD drives can do everything that CD drives can, plus read DVDs. If you have a DVD drive, you can watch movies on your computer. Many DVD drives can record data onto blank DVDs.

Floppy disk drive

Floppy disk drives store information on floppy disks, also called floppies or diskettes. Compared to CDs and DVDs, floppy disks can store only a small amount of data. They also retrieve information more slowly and are more prone to damage. For these reasons, floppy disk drives are less popular than they used to be, although some computers still include them.

A USB flash drive is a data storage device that consists of flash memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than a floppy disk.

USB flash drives are often used for the same purposes for which floppy disks or CD-ROMs were used. They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because of their lack of moving parts. Until approximately 2005, most desktop and laptop computers were supplied with floppy disk drives, but floppy disk drives have been abandoned in favor of USB ports.

A flash drive consists of a small printed circuit board carrying the circuit elements and a USB connector, insulated electrically and protected inside a plastic, metal, or rubberized case which can be carried in a pocket or on a key chain, for example. The USB connector may be protected by a removable cap or by retracting into the body of the drive.

 Tertiary Storage

In Tertiary Storage or Tertiary Memory, a robotic arm mounts (inserts) and dismounts removable mass storage media into storage devices according to the system’s demands. This stores information that is infrequently accessed. These types of storage devices are much slower than secondary storage (e.g. 5-60 seconds vs. 1-10 milliseconds.)

Tertiary Storage is widely used in large data stores and is accessed without human operators. Typical examples of this storage system are tape drives, libraries and optical jukeboxes.

Volatile and Non-Volatile storage Classification

Volatile Memory

Volatile memory, also known as volatile storage, is computer memory that requires power to maintain the stored information, unlike non-volatile memory which does not require a maintained power supply. It has been less popularly known as temporary memory.

Most forms of modern random-access memory (RAM) are volatile storage, including dynamic random-access memory (DRAM) and static random-access memory (SRAM). Content addressable memory and dual-ported RAM are usually implemented using volatile storage. Memory cache and Registers are also considered as volatile memory.

Early volatile storage technologies include delay line memory and Williams’s tube.

Non-volatile Memory

Non-volatile memory is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory (ROM), flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy disks, and magnetic tape), optical discs (e.g. CDs and DVDs ), and early computer storage methods such as paper tape and punched cards.

Non-volatile memory is typically used for the task of secondary storage, or long-term persistent storage.

Input Devices (classify them) include bar code reader)

Input is any data or instructions entered into the memory of a computer. Two types of input are data and instructions. Data is a collection of unorganized items that can include words, numbers, pictures, sounds, and video. A computer processes data into information. Information is therefore organized, meaningful, and useful. Instructions can be in the form of programs, commands, or user responses. A program is a series of instructions that tells a computer how to perform the tasks necessary to process data into information. A command is an instruction given to a computer program. A user response is an instruction you issue to the computer by responding to a question posed by a computer program.

Any hardware component that allows you to enter data, programs, commands, and user responses into a computer is an input device.

Examples of input devices include: Keyboard, Mouse, Light pen, Joystick, Scanner, Touch screen, Microphone, Barcode reader etc.

Input Devices may be classified into:

  • Keying Devices
  • Pointing Devices
  • Scanning Devices
  • Speech Devices
  • Other Digital Devices 

Keying Devices

Keying Devices enter (information or instructions) in a computer or other device by means of keystrokes.

Keypad

A keypad is a set of buttons arranged in a block or “pad” which usually bear digits, symbols and usually a complete set of alphabetical letters. A diagrammatic representation of a keypad is shown below:

Keyboard (with the aid of a diagram describe various types of computer keyboard keys)

 The keyboard is the most common input device that contains keys you press to enter data into a computer. Desktop computer keyboards usually have from 101 to 105 keys, while keyboards for smaller computers contain fewer keys.

There are four main areas on a PC’s keyboard (as shown in this figure):

Function keys: These keys are positioned on the top row of the keyboard. They’re labeled F1, F2, F3, and on up to F11 and F12.

Typewriter keys: These keys are the same types of keys you find on an old typewriter: letters, numbers, and punctuation symbols.

Cursor-control keys: Often called arrow keys, these four keys move the text cursor in the direction of their arrows. Above them are more cursor-control keys — the six-pack of Insert, Delete, Home, End, and Page Up, and Page Down.

Numeric keypad: Popular with accountants, bank tellers, and airline ticket agents, the numeric keypad contains calculator-like keys.

Pointing Devices (check)

In a graphical user interface, the pointer is a small symbol on the screen. A pointing device is an input device that allows you to control the pointer. Common pointing devices include the mouse, trackball, touchpad, joystick, touch screen, light pen, and a stylus.

Track ball

A trackball is a stationary pointing device with a ball mechanism on its top. The ball is rotated by hand to control cursor movement. In essence a trackball can be thought of as an upside down mouse. Whereas the entire mouse is moved, trackball is stationary and the ball is rotated by hand.

Joystick

A joystick is used to move the cursor from place to place, and to click on various items in programs. Joysticks are used mostly for computer games because they let you move quickly and accurately in any direction.

Light pen

A light pen is an input pointing device that resembles a ball pen and has a light sensitive point. It selects items or chooses commands, draw by simple touching on the screen. A light pen does not emit light; rather it contains sensors that send a signal to the computer when it detects the light

Stylus

The stylus is the primary input device for personal digital assistants and smartphones that require accurate input, although devices featuring multi-touch finger-input with capacitive touchscreens are becoming more popular than stylus-driven devices in the smartphone market.

Touchpad

A touchpad or trackpad is a flat surface that can detect finger contact. It’s a stationary pointing device, commonly used on laptop computers. At least one physical button normally comes with the touchpad, but the user can also generate a mouse click by tapping on the pad. Advanced features include pressure sensitivity and special gestures such as scrolling by moving one’s finger along an edge.

Touchscreen

A touch screen is a computer screen or other screen that you can touch with your finger to enter information.  Examples of touch screens include a smart board, a microwave, a dishwasher, or an ATM at a bank.

Mouse

A mouse is the common pointing device and is designed to fit comfortably under the palm. It contains one or more buttons on top which are used to select items and choose commands. Although mice come in many shapes, the typical mouse does look a bit like an actual mouse. It’s small, oblong, and connected to the system unit by a long wire that resembles a tail. Some newer mice are wireless. On the underside of a mouse is a device that detects the direction and speed of its movement across a flat surface.

How a mouse works

A mouse usually has two buttons: a primary button (usually the left button) and a secondary button. Many mice also have a wheel between the two buttons, which allows you to scroll smoothly through screens of information.

As you move a mouse across a flat surface, the movement is translated into signals that are sent to the computer, and the pointer on the screen also moves  in the same direction. When you want to select an item, you point to the item and then click (press and release) the primary button. Pointing and clicking with your

Types of Mice

  • Mechanical: This is a type of computer mouse that has a rubber or metal ball on its underside and it can roll in every direction.  There are sensors within the mouse, which are mechanical, detect the direction in which the ball is moving and moves the pointer on the screen in the same direction.  A mouse pad should be used under the mouse to run on.
  • Opt mechanical mouse

The optical-mechanical or Optomechanical mouse consists of a ball that rolls one of two wheels inside the mouse. This wheel contains a circle of holes or notches that allow a LED light to be shined through and detected by a sensor, as each wheel spins they represent the X or Y axis for the mouse pointer. This mouse is much more accurate than the traditional mechanical mouse that used only wheels and rollers, however is not as good as an optical mouse.

  • Optical mouse

This type uses a laser for detecting the mouse’s movement.  You don’t need a mouse pad but you can use one made for optical mice.  Optical mice do not have any mechanical moving parts.  The optical mouse responds more quickly and precisely than the mechanical and opt mechanical mice and now that they have been around awhile the price is pretty comparable.

  • Cordless or wireless mouse

Cordless or wireless mice transmit data via infrared radiation or radio  frequency (RF). RF wireless mice require two components to work properly – a radio transmitter and a radio receiver. A radio frequency (RF) transmitter is usually integrated inside the mouse. The mouse records its movements and buttons that are clicked and then sends this information via radio signals to the receiver.The receiver is connected to the computer through a serial or USB port. It receives these RF signals, decodes them, and then sends these signals directly to the computer.

  • Scanning Devices (check)

A scanner is an electronic device that scans text documents, images, or objects to convert them into a digital format. The common types of scanners we see today are flatbed scanners, handheld scanners, sheetfed scanners, etc.

Scanners are classified as follows:

Optical scanners

They include optical character/image Recognition (OCR), Optical Mark Recognition (OMR) and Optical Bar Recognition (OBR) scanners.

  • Optical character/image scanner (OCR)

It is used to scan characters and images. Using this type of a scanner, one can scan real objects.

  • Optical Mark Recognition (OMR)

This type of scanner uses mark-sensing to scan and translate the location of a series of pen or pencil marks into computer- understandable form.

This scanner is commonly used during marking and scoring of K.C.P.E multiple choices examination questions/answers.

  • Optical bar recognition (OBR)

Optical bar scanners scan and translate a bar code into machine understandable mode.bar codes are a series of vertical lines of varying widths and can also include numbers and letters. The retail stores use bar codes on products to make data entry faster and more accurate. This improves their stock control.

 

Magnetic scanners

  • Magnetic –ink character recognition (MICR)

It is a type of a scanner that is able to detect character written in special magnetic ink. The magnetic ink is used in document such as bank cheese and credit card slips because the (MICR) reader can read the magnetic characters no matter how much a user might have written on or over them.

  • Magnetic strips

They are thin bands of magnetically encoded data found on many credit cards. The data in these cards may be account numbers or special access codes. There are scanners which recognize the data in such magnetic stripes; these stripes may be used to gain entry to certain restricted areas. 

Speech recognition

Voice input is the process of entering data by speaking into a microphone that is attached to the sound card on a computer. Voice recognition is the computer’s capability of distinguishing spoken words. The first voice recognition programs were speaker dependent. With speaker-dependent software, the computer makes a profile of your voice, which means you have to train the computer to recognize your voice. Today, most voice recognition programs use speaker-independent software, which has a built-in set of word patterns and does not have to be trained to recognize your voice. Some voice recognition software requires discrete speech, meaning that you have to speak slowly and separate each word with a short pause. Most voice recognition products, however, support continuous speech, allowing you to speak in a flowing conversational tone.

Other input devices

Other input devices include the digital camera, CD-ROM, DVD-ROM and the webcam.

Digital Camera

A digital camera is used to take pictures and store the photographed images digitally instead of on traditional film. Pictures are stored on a storage medium, such as a floppy disk, compact flash card, memory stick, mini-CD, etc. Many digital cameras allow you to review and edit the images while they are in the camera. You also can download, or transfer a copy of, the stored image to a computer. Once on a computer, the pictures can be edited with photo-editing software, printed, faxed, sent via electronic mail, included in another document, or posted to a Web site.

There are three basic types of digital cameras. A studio camera is a stationary digital camera used for professional studio work. A field camera is a portable camera, often used by photojournalists, that has many lenses and other attachments. A point-and-shoot camera is more affordable and lightweight and provides acceptable quality photographic images for the home or small business user.

Webcam

A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, Ethernet, or Wi-Fi.

Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations.

Webcams are known for their low manufacturing cost and flexibility, making them the lowest cost form of video telephony.

Scanner (check)

A scanner is an electronic device that scans text documents, images, or objects to convert them into a digital file format. The common types of scanners we see today are flatbed scanners, handheld scanners, sheetfed scanners, etc. Scanners usually come with software that lets you resize or modify a captured image.

Explain how scanners and other reading devices work

Scanners and optical readers can capture data from a source document, which is the original form of the data. A scanner is a light-sensing input device that reads printed text and graphics and then translates the results into a form a computer can use. One of the more popular scanners is a flatbed scanner, which works similarly to a copy machine except it creates a file of the document in memory instead of a paper copy. Many scanners include OCR software, which converts a scanned image into a text file that can be edited. An optical reader uses a light source to read characters, marks, and codes and converts them into digital data that a computer can process. Three types of optical readers are optical character recognition, optical mark recognition, and bar code scanner. Optical character recognition (OCR) is a technology that reads typewritten, computer printed, or handwritten characters from ordinary documents and translates the images into a form that the computer can understand. Optical mark recognition (OMR) devices read hand-drawn marks such as circles or rectangles. A bar code scanner uses laser beams to read bar codes, which are identification codes consisting of vertical lines and spaces of different widths. Another type of reader, called a magnetic-ink character recognition (MICR) reader, reads text printed with magnetized ink and is used almost exclusively by the banking industry.

Speech recognition

Output devices

Monitor

A monitor displays information in visual form, using text and graphics. The portion of the monitor that displays the information is called the screen. Like a television screen, a computer screen can show still or moving pictures.

There are two basic types of monitors: CRT (cathode ray tube) monitors and LCD (liquid crystal display) monitors. Both types produce sharp images, but LCD monitors have the advantage of being much thinner and lighter. CRT monitors, however, are generally more affordable.

Printer (include types of printers, their characteristics and differences)

A printer transfers data from a computer onto paper. You don’t need a printer to use your computer, but having one allows you to print e‑mail, cards, invitations, announcements, and other materials. Many people also like being able to print their own photos at home.

The two main types of printers are inkjet printers and laser printers. Inkjet printers are the most popular printers for the home. They can print in black and white or in full color and can produce high-quality photographs when used with special paper. Laser printers are faster and generally better able to handle heavy use.

 

Plotters

Speakers

Speakers are used to play sound. They may be built into the system unit or connected with cables. Speakers allow you to listen to music and hear sound effects from your computer.

 

Speakers are one of the most common output devices used with computer systems. Some speakers are designed to work specifically with computers, while others can be hooked up to any type of sound system. Regardless of their design, the purpose of speakers is to produce audio output that can be heard by the listener.

(Other output devices)Identify the purpose of data projectors, fax machines, and multifunction devices

A data projector takes the image on a computer screen and projects it onto a large screen so that an audience of people can see the image. Two smaller, lower priced data projectors are an LCD projector, which uses liquid crystal display technology, and a digital light processing (DLP) projector, which uses tiny mirrors. A facsimile (fax) machine transmits and receives documents over telephone lines. A fax modem is a communication device that allows you to send (and sometimes receive) electronic documents as faxes. A multifunction device (MFD) is a single piece of equipment that looks like a copy machine but provides the functionality of a printer, scanner, copy machine, and sometimes a fax machine

Classification of computers

Computers can be classified according to:

  • According to Technology/functionality
  • According to Purpose
  • According to Size

According to size

  • Supercomputers
  • Mainframe Computers
  • Minicomputers
  • Microcomputers, or Personal Computers

Mainframe Computers
Mainframe computers are very large, often filling an entire room. They can store enormous of information, can perform many tasks at the same time, can communicate with many users at the same time, and are very expensive.  The price of a mainframe computer frequently runs into the millions of dollars. Mainframe computers usually have many terminals connected to them. These terminals can be located in the same room with the mainframe computer, but they can also be in different rooms, buildings, or cities. Large businesses, government agencies, and universities usually use this type of computer.

Minicomputers

Minicomputers are much smaller than mainframe computers and they are also much less expensive. The cost of these computers can vary from a few thousand dollars to several hundred thousand dollars. They possess most of the features found on mainframe computers, but on a more limited scale. They can still have many terminals, but not as many as the mainframes. They can store a tremendous amount of information, but again usually not as much as the mainframe. Medium and small businesses typically use these computers.

Microcomputers

Microcomputers are the types of computers we are using in our classes . These computers are usually divided into desktop models and laptop models. They are terribly limited in what they can do when compared to the larger models discussed above because they can only be used by one person at a time, they are much slower than the larger computers, and they can not store nearly as much information, but they are excellent when used in small businesses, homes, and school classrooms. These computers are inexpensive and easy to use. They have become an indispensable part of modern life. Examples include:

Desk Top

Lap Top

Palm Top

PDA

Super Computers

Super Computers, as the name suggest are the most powerful computers even than mainframe. Actually, when we optimize a mainframe computer then we get super computer.
Super computers can process huge amounts of data, are the biggest in size and the most expensive in price than any other. It can process trillions of instructions in seconds.

Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling.

According to Technology/functionality

  • Analog Computers
  • Digital Computers
  • Hybrid Computers

Analog Computers:- These computers recognize data as a continuous measurement of a physical property ( voltage, pressure, speed and temperature).

Example: Automobile speedometer

Digital Computers:- These are high speed programmable electronic devices that perform mathematical calculations, compare values and store results. They recognize data by counting discrete signal representing either a high or low voltage state of electricity.

Hybrid Computers:-A computer that processes both analog and digital data.

 According to Purpose

  1. General purpose Computers
  2.  Special Computers

 General purpose Computers

A ‘General Purpose Computer’ is a machine that is capable of carrying out some general data processing under program control.

Refers to computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program.

Benefits ( Advantages) of using computers

  1. The use of computers has facilitated sharing of resources in organizations.

Resources such as printers and files can be shared by employees in an organization. This saves a lot of money.

  1. Word processing. A computer allows a person to manipulate data easily and quickly, create text documents, edit them, print them, manipulate images, print them
  2. They improve learning experience for children. The use of computers enable children to access quality educational resources, learning-enhancing games and homework help.
  3. Computers help children to use all of their senses to extract information. They fascinate kids and can draw their full attention, which often results in a deeper focus and concentration.
  4. Internet/communications. Computers enable people download information over the Internet, interact with other people easily using chatting and videoconferencing facilities etc
  5. Provision of quality service/goods. Computers are used to provide better service (for example, banking or airline reservations) or a higher quality product (for example, automobile parts).
  6. Assist in decision making. They are used to provide decision-makers with accurate, up-to-date information, so that better business decisions can be made.
  7. Provision of repetitive tasks. Computers are used to monitor instruments, as in process control applications, thus relieving human beings from drudgery, enabling them to concentrate on more creative tasks. A computer can also provide round-the- clock attention to patients, relieving nurses for other duties.
  8. In a teaching environment, the computer can be a patient, ever-attentive disseminator/tester of information.
  9. Provision of entertainment. Computes can be the source of hours of fun when use to play a fascinating range of games, listening to music and watching movies.
  10. Shopping. Through the internet people are now able to shop on-line.

Challenges (Disadvantages) of using computers

  1. The introduction of computers in the workplace has caused unemployment and apprehension among workers. This is because a computer is able to do work that could have been done by many people.
  2. Errors and breakdowns in computer systems have caused hardships and inconveniences to individuals.
  3. Infringement of privacy of individuals. Unless computer systems are properly monitored and controlled, there is a very real threat to the privacy of ordinary citizens. While privacy problems existed before there were computers, computers have changed the privacy landscape considerably. One obvious area of change is in the ability to gather and process millions of minor transactions, and to combine these with millions of other transactions to create a profile of who we are, what we buy, where we go.
  4. Cheating by student One disadvantage of owning a computer is the information that students can access from the Internet. If a student needs to research information for school, they merely access a relevant site and download the information, rarely paying attention to what is written.
  5. Viruses can spread to other computers throughout a computer network.
  6. There is a danger of hacking, particularly with wide area networks.
  7. Fraud
  8. people not going out as much,
  9. bad posture from sitting too long at a desk,
  10. repetitive strain injuries

Computer software

Meaning of computer software

Software is a collection of computer programs, instructions, procedures and documentation that enables a user to interact with the computer or have the computer perform specific tasks for them. Without any type of software the computer would be useless. For example, you wouldn’t be able to interact with the computer without software called the operating system.

The two main types of software are system software and application software.

System software

System software is responsible for controlling, integrating, and managing the individual hardware components of a computer system so that other software and the users of the system see it as a functional unit without having to be concerned with the low-level details such as transferring data from memory to disk, or rendering text onto a display.

There are two types of system software. These are:

  1. The operating system which allows the parts of a computer to work together by performing tasks like transferring data between memory and disks or rendering output onto a display device. It also provides a platform to run high-level system software and application software. Prominent examples of operating systems include Microsoft Windows, Mac OS X and Linux.
  2. Utility (or housekeeping) software which helps to analyze, configure, optimize and maintain the computer. It performs a single task or a number of small tasks. Examples of Utility software are:
    Disk defragmenters
    Anti-virus software
    Encryption utilities.

Application software

Application software, on the other hand, is used to accomplish specific tasks other than just running the computer system. Application software may consist of:

  • A single program, such as an image viewer
  • A small collection of programs (often called a software package) that work closely together to accomplish a task. E.g a spreadsheet or text processing software;
  • A larger collection (often called a software suite) of related but independent programs and packages that have a common user interface or shared data format. Examples include:
  1. Microsoft Office, which consists of closely integrated word processor, spreadsheet, database, etc.
  2. A software system, such as a database management system, which is a collection of fundamental programs that may provide some service to a variety of other independent applications.

Software is created with programming languages and related utilities, which may come in several of the above forms: single programs like script interpreters, packages containing a compiler, linker, and other tools; and large suites (often called Integrated Development Environments) that include editors, debuggers, and other tools for multiple languages.