Introduction
In this age of technology, Information is Power! Stay Safe!
What is Peer Pressure?• Now that you have joined Senior One, it will be natural to want to be part of a group of friends. You will also want to feel that your friends appreciate you. • Peer pressure is when friends persuade you to something that you would not want to do.
• In other cases, they may make you do something that you would want to do; you may lack the courage to say NO.
How will peer Pressure affect you?
• Peer pressure will compel you to change your attitude, behavior, and morals in order to fit in the group of friends that you have.
• There is good and bad peer pressure.
• Good Peer pressure will make you grow. It will challenge or motivate you to do your best in school.
• Bad peer pressure will make you do things that may have negative effects on your health, and your academic performance. Peer pressure will affect your taste of fashion, and your ability to make responsible choices in life. Do not be pressured to use alcohol, cigarettes, and other harmful drugs. Do not be pressured to get into relationships that you may not be ready for. What can you do about peer pressure?
• You have a whole future ahead of you. You aspire to join a certain career when you complete colle
The chances of your
dream becoming a reality will be affected by the decisions you will make today. You must, therefore, take charge of your life. You must take responsibility for what you do and how you think. You must choose to resist bad peer pressure. It will not be easy, but you can do it.To deal with bad peer pressure you must be prepared to say “NO!” to some friends. If you let them manage your life, they may not have your best interests at heart.
• Suppose one of your friends were to offer you a cigarette. This is the time to stand up for yourself. You must say, “No, that is a cancer stick, and I do not wish to die young.” If this friend keeps asking you to take a puff, this is when you must give yourself a talk. You may whisper to yourself, “I make a decision today not to ever try a cigarette, or any other harmful drug for that matter. I truly know that the decision I have made is the perfect one for me.” You should then be able to tell your “friend, the cigarette slave” exactly what you have decided. Believe it, they will respect you for standing up for yourself and not giving in. This may sound easier
said than done, doesn’t it? It will take a great amount of will power and ability to love and respect yourself to stand by your grounds.
Information is Power! Search for information that will help you make informed and wise decisions. Arm yourself with wisdom and knowledge and some decision making skills. In this way, you will be able to live your own life successfully.
• Know your friends and “friends”. Deciding who to listen to and who to avoid is the biggest favour you can do to yourself. It will help you to resist unwanted negative peer pressure. Remember, You must live your life. No one else can do that for you. It is your life; build or break it. It is your full responsibility to determine what you want in life!
Information and Communication Technology Foundation
Key Unit Competency
By the end of this chapter, you should be able to explain the foundation of Information and Communication Technology (ICT).
Learning Objectives
(a) Knowledge and Understanding
By the end of this chapter, the student should be able to:
(i) Explain ICT related concepts and terms.
(ii) List ICT tools and their appropriate use in daily life.
(b) Skills
By the end of this chapter, you should be able to:
(i) Use ICT related terms appropriately.
(ii) Use ICT equipment, namely radio, mobile phones, televisions and computers in their relevant context by turning on and off, navigating and accessing their features.
(iii) Identify areas where ICT is used. (iv) Select appropriate ICT tools.
(v) Evaluate the advantages and disadvantages of using ICT in society.
(c) Attitudes and Values
By the end of this chapter, you should be able to:
(i) Appreciate the role played by ICT in the evolution of society.
(ii) Enjoy using ICT and appreciate the benefits and effectiveness of different ICT tools
Keywords in the chapter
• Hardware • Software • Data gathering • e-Business • Telecommuting • Signals • Analog Data • Distance Learning • Digital data
Definition of Data
Data can be defined as raw facts that have been entered into a computer but have not been processed. It refers to statistics, symbols, basic facts, figures, numbers or simply records. Note that the term data is the plural form of datum. However in modern usage, the term data is used both as a singular and plural term.
Examples of data include:
• Number of students in a class • Number of ICT textbooks for Senior One ordered by a school • Number of computers in a school computer laboratory
Types of data
Two main types of data in a computer are:
(i) Analog data is that which is in continuous form.
(ii) Digital data is data which is in discrete form.
Analog data and Digital data
Analog data is in continuous form. It is processed using computers which process the continuously changing variable quantities. Analog data can be represented as a wave form. Examples of analog data include temperature, pressure and humidity.
Digital data, unlike analog data, does not vary continuously with time. Digital data are discrete; that is, their values have only two possible states: that is, 0 or 1; on or off; and true or false. Example of digital data is data held in a computer.
Data gathering
This is the systematic collection of data from various sources for a specific purpose.
Methods of data gathering
Examples of data collection methods are: observation, interviews, questionnaires, data logging, direct data capture, or by studying existing documents.
•Observation: This is the careful study and recording of data as it occurs in the environment
• Interviews: This is gathering of data by asking questions orally. The person asking the questions is the interviewer. The respondent is the interviewee.
• Questionnaires: This involves the use of a set of written questions.
• Data logging: This is the automatic collection of data over a period of time using sensors connected to a computer.
• Direct data capture: This involves the use of devices such as Optical Mark Recognition\Reader (OMR), Optical Card Recognition\Reader (OCR) and Optical Bar Recognition\ Reader (OBR) among others.
• Study of existing documents: This involves going through documents such as reports, journals, articles, and records of previous interviews.
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Information
Information can be defined as processed facts or data that is meaningful and useful to the user.
Factors affecting the quality of information.
1. Accuracy: This is the measure of how close data is to the original. Accurate data should be the same as the original. For example: 5.263 is the original data. If it is captured as 5.26, then it will be more accurate than if it captured as 5.3.
2. Relevance: Data is considered to be relevant if it can be used for what it was intended. Data that is not accurate or timely is therefore not relevant. Relevant data should therefore be appropriate to the user needs. For example, an academic assignment that is received late may not be relevant because it may not be used to process the average mark for the student.
Fig. 1.1: Factors affecting the quality of the information.
3. Timeliness/Age: Information changes over time. This means that out-of-date information can be irrelevant; therefore information needs to be up-to-date to avoid cases of misleading or giving the wrong picture of what is happening.
4. Completeness: Information should be comprehensive. Partial information may only represent a small part of the whole picture. If part of the information is missing, then one will not be able to make use of it or make accurate decisions.
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5. Presentation: Information should be presented in an organized manner to make it more useful. Presenting information using the best method, possibly by sorting or organizing it makes it much easier to understand and to be more useful.
Communication
Communication refers to the exchange of information. In computing, it refers to the process of transmitting information or data signals from the source (sender) to the destination (receiver) through a transmission channel.
Elements of Communication
Communication involves the following elements.
(i) Source /Sender: This refers to the communicator or originator of the message. Sometimes, the sender becomes the receiver of the message.
(ii) Content: This refers to the message being communicated. It may be an attitude, opinion, views, orders, or suggestions.
(iii) Communication Channel: This refers to the medium of transmission used to deliver the message.
(iv) Receiver: This is the person to whom the sender transmits the message.
(v) Feedback: This is the reaction given after the message is received. It is the output from the receiver in order to improve performance by providing self-corrective action. Feedback gives the communication progress. It can be negative or positive.
Types /Ways of Communicating
There are three basic types of communication which include:
• Verbal • Non-verbal • Written
Verbal or oral communication: This is the use of spoken words to communicate a message. It involves both speaking and listening.
Non-verbal Communication: It includes the use of body language, facial expressions, gestures, and posture. Non-verbal responses can sometimes contradict verbal communication. This changes the effectiveness of the message.
Written Communication: It refers to messages that are sent to receivers in writing. This type of communication is essentially used for communicating information such as statistics or other data that cannot be easily communicated through speech alone. This allows information to be recorded for reference at a later date.Written communication has enabled the young citizens to learn about the history about our country.
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Technology
Technology refers to the application of scientific knowledge to the practical purposes in the human environment. For example, in industries and learning institutions among others. Technology includes the use of materials, tools, techniques, and sources of power. Science is concerned with how and why things happen while technology focuses on making things happen.
Technology of Teaching
This refers to instructional approaches that are systematically designed and applied in specific ways. It includes the following:
• The use of well-defined objectives.
• Specific instructional procedures based upon the tasks that learners are required to study.
• Small units of instruction that are carefully arranged.
• A high degree of teacher activity.
• High levels of student participation.
• Careful monitoring of student performance
Assistive Technology
Assistive technology applies various types of services and devices designed to help people with disabilities to function within an environment. It includes electronic, microprocessor-based equipment, mechanical, non-mechanical, and specialized instructional materials and strategies.
Assistive technology enhances the lives of people with disabilities in the following ways:
(a) Helps them in learning.
(b) Improves their quality of life.
(c) Makes the environment more user-friendly.
(d) Improves their independence.
(e) Allows them to compete in the workplace.
Medical Technology
It is the use of scientific knowledge in healthcare to diagnose, monitor and treat diseases or medical conditions. For example, artificial limbs, knee and hip implants can help people to function. Kidney function can also be assumed by kidney dialysis machines. In addition to keeping individuals alive, technologies such as these can help people to fully participate in community, school, and work activities.
Information Technology (IT)
It refers to the application of computer and telecommunication equipment to manipulate, store, retrieve and transmit data.
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ICT (Information and Communication Technology)
ICT is the abbreviation for Information and Communication Technology. ICT refers to the application of information technology and telecommunication that includes the use of computer hardware, software, and telecommunications equipment for transmission and presentation of information.
ICT Equipment
The following are some of the equipment used in ICT:
Radio: This is a device that is used to receive radio signals from broadcasting stations and convert them into sound. A radio antenna must be used but since the antenna will pick up many radio signals at a time, a radio tuner is necessary to tune into a particular frequency (or frequency range). The radio is used to relay news, announcements, music, advertisement and educational programmes among others.
Fig. 1.2: A radio
Television: The television or TV is an electronic device for receiving and reproducing images and sound of combined video and audio signals. It is used to relay news, announcements, music, advertisements, and educational programmes among others.
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Fig. 1.3: A television set
Mobile phones: They are also referred to as cellular phones or cell phones. These are electronic telecommunication equipment that connect to a wireless communication network through radio waves or satellite transmission. Most of these devices provide audio communication, Short Message Services (SMS) or Multimedia Message Services (MMS). Current cell phones are also capable of providing Internet browsing, as well as email services.
Smartphone: This is a cellular phone that performs most of the functions of a computer, typically having a touch screen, internet access, and an operating system capable of running applications
Tablets: A tablet is a portable computer fitted with a touch screen display, circuitry, and battery in a single device. It is also equipped with sensors, including cameras, a microphone, and an accelerometer. The touch screen display is operated by swiping a finger or a stylus.
Billing Machines: A billing machine is used in business to itemize, compute customer accounts, generate bills, provide customer invoices, and send account records.
Billing Machines: A billing machine is used in business to itemize, compute customer accounts, generate bills, provide customer invoices, and send account records.
Satellite: A satellite is a self-contained communications system. It revolves around a planet in a circular or elliptical path. It has the ability to receive signals from the Earth and to retransmit those signals back. An example of an earth station that communicates with orbiting satellites is Very Small Aperture Terminal (VSAT).
Projector: It is an output device that uses light and lenses to take images generated by a computer and reproduce them on a larger flat screen or wall (usually lightly coloured). For example, projectors are used in meetings to help ensure that all participants can view the information being presented
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Computer: It is an electronic device that accepts data as input. It processes data using a set of instructions referred to as software or programs and either stores or produces information as output.
Use and Interact with ICT equipment
(a) Radio: To use a radio:
(i) Connect the power cable to the power supply or insert dry cells in the radio battery compartment
(ii) Switch on the power button.
(iii) Using the frequency adjustment, knob tune to the desired frequency. One can change the radio to different frequencies to listen to other channels.
(b) Television: Connect the television to the source of power.
(i) Switch on the TV.
(ii) Ensure that the set top box is on and well-configured as directed by the manufacturer.
(iii) Tune to the desired channel.
(iv) Using the remote control or channel buttons on the TV set, select any other channel of interest.
9(c) Phones: Switch on the mobile phone.
(i) It opens the home screen.
(ii) The mobile phone displays different menus that are available.
(iii) Select the menu of choice. In some mobile learning applications currently available, mobile features are being utilized for various educational practices. These include the use of Short Message Services (SMS), GPS, camera, browsing, downloading, Bluetooth, Wi-Fi, voice calls, and gaming.
(d) Computer: Connect the computer to the source of power.
(i) Switch it on and allow it to boot up.
(ii) After the boot up process, the desktop is displayed with icons.
(iii) Click on the start button located on the task bar.
(iv) From the menu, select the desired program to work with.
Importance of ICT
(a) Education
ICT has facilitated education through Computer Aided Learning (CAL), Computer Aided Instruction (CAI), Computer Aided Assessment (CAA), E-learning and computer based simulation among others.
(i) CAL: This is the integration of ICT into the learning process. It is also known as Computer Based Training (CBT). It involves the use of computers in education and training. CAL techniques include:
• Educational games: These are electronic games that have content relevant to a subject area. For example the Carmen sandiego helps students learn World geography.
• Problem solving tutorials: These are self-instructional programs that guide the learner through learning and resource material acting as their virtual teacher.
• Drill and practice: A set of questions from a database are given to students repeatedly to practice skills and concepts. The questions usually have straightforward answers and are therefore very easy for the computer to mark.
• Simulation: Multimedia content is used to mimic real learning activities. For example it can be used to mimic a chemistry experiment.
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(ii) CAI: Computer-Aided Instruction (CAI) includes the use of computers to teach academic skills to students and to help them develop communication, language and skills. It includes computer modelling and computer tutors for example, the typing tutor.
(iii) CAA: It is a computerised innovation used in marking multiple choice examination papers where a box is marked in pencil to indicate the candidate’s preferred answer. An Optical Mark reader (OMR) can identify the box having a mark and award a score appropriately.
(iv) E-learning: It is the delivery of educational programs, training or learning materials by electronic means. It involves the use of electronic devices such as mobile phones, tablets, computers and the Internet.
(b) Health
The following are some of the uses of ICT in healthcare:
(i) ICT is used in the medical sector to keep records of patients.
(ii) In the Intensive Care Unit (ICU), ICT is used to control life support machines.
(iii) ICT is also used to conduct brain scans, body X-rays, ultra sounds, and other body scans.
(iv) Patients also receive medical diagnosis and advice from foreign medical experts through the use computerised expert systems.
(v) Knowledge enrichment, research, and education: Many doctors, pharmacists and medical practitioners use the Internet to keep themselves updated. They do research on specific questions and areas of interest. They also take refresher courses to enrich their medical knowledge in order to offer better services to their patients.
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(vi) ICT-based equipment such as the Magnetic Resonance Imaging (MRI), X-Rays and CT-Scan (Computed Tomography Scan) are used to diagnose complicated medical conditions.
(c) Business
Business refers to commercial activities carried out for profit. Electronic business (e-business) is the application of ICT in support of business activities. Examples of ICTbased business activities include:
(i) Online Shopping: The use of plastic money, that is, money held in electronic credit cards or mobile devices makes it possible to order for goods and services from the comfort of one’s home or office.
(ii) Advertising and Marketing: Through the use of websites, organizations are able to advertise at a low cost. Most businesses now use websites with high web traffic as platforms for creating awareness about their products and services. For example the OnLine eXchange(OLX) website is used for selling second hand items.
(iii) Use of electronic billboards: These are created using graphic software such as Adobe Illustrator and Adobe Photoshop.
(iv) Promotional Presentations: These could be created using PowerPoint presentations, video presentations, and animation software.
(d) Communication
ICT is used to transmit textual, visual and audio information from one point to another through the use of telecommunication equipment at a very high speed. This is achieved through the use of electronic mails (e-mails), live chatting systems, online meetings (via Skype), short messages services (SMS), facsimile (fax), and video-conferencing among others.
(e) Banking
ICT can be used in banking where transactions such as electronic fund transfer (EFT), Internet banking, mobile banking, use of Automated Money Transfer, Automated Teller Machine (ATM), Database Management and Cheque clearing are made possible. Customers are also enabled to access their bank details through SMS alerts.
(f) Manufacturing and Production
ICT-based systems such as Computer Integrated Manufacturing (CIM), Computer Aided Design (CAD) and Computer Aided Engineering (CAE) are used to monitor and control production processes in factories.
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(g) Computer Simulation
This is the modelling of a real situation using a computer. It is used to model industrial processes enabling better understanding and improvement of production system. The idea of simulation is to try and find out what mechanisms to control. A simulation also shows how a production system behaves and consequently predict or influence the behaviour of the system in the future. In industries, simulation can be used to:
(a) Train workers such as pilots.
(b) Study the efficiency of a production process.
(c) Evaluate how safe the activities in a factory are. Simulation is also used in education in mathematics as well as modelling of many natural systems.
Advantages of ICT
(i) Use of ICT helps in performing tasks faster and more efficiently.
(ii) ICT enables very high accuracy levels in large-scale production.
(iii) Greater access to ICT technology has helped to bridge the cultural gap by helping people from different cultures to communicate with each other, and allow exchange of ideas and views, hence increasing awareness.
(iv) ICT facilitates efficient sending and accessing of information from different locations across the world. (v) ICT tools help organizations to gain a competitive edge over their competitors.
Disadvantages of ICT
(i) The initial capital investment of buying new equipment and the cost of maintenance is usually high.
(ii) ICT and automation can lead to loss of jobs, especially for computer-illiterate persons.
(iii) ICT equipment such as computers can lead to health problems. Some known health risks related to computer use include eye problems, backache, and wrist injuries.
Current use of ICT in Rwanda
Rwanda’s Vision for 2020 framework addresses the educational, agricultural, industrial and social elements of the country’s economy. The Rwandan government has invested greatly in a knowledge-based economy with ICT as its cornerstone.
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(a) ICT use in Education
(i) Learning in schools: The government project for One Laptop Per Child (OLPC) has facilitated the use of computers in learning institutions. The content has been developed by the National Curriculum Development Centre (NCDC). The students are able to learn turtle, Gnome, scratch, and GIS among other applications.
(ii) Distance Learning: ICT has facilitated the running of distant educational programmes. An example is the African Virtual University (AVU) in collaboration with the National University of Rwanda (NUR) and Kigali Institute of Science and Technology (KIST). This program offers further training for secondary school teachers.
(iii) E-ICT: Electronic-ICT is easily accessible to anyone interested in high-technology courses. Such programs enable one to keep up-to-date with new technologies. The curriculum programs include ICDL (International Computer Driving License). This course teaches all Microsoft Office applications and Cisco Networking among others.
(b) ICT use in the Health Sector
(i) Record keeping: The use of systems such as Open-Source Medical Records ( Open MRS) and Treatment and Research Aids Centre (TRAC) net system facilitates nationwide tracking of patient data and managing clinical health information.
(ii) Mobile e-Health systems: They are used by community health workers to collect data for patients and health management, for example, Open MRS and TRACnet systems
(iii) Telemedicine: This facility allows the sharing of clinical information between urban and rural hospitals. An example is King Faisal Hospital that connects Kabgayi and Musanze, allowing citizens to receive specialized treatment services remotely without travelling to Kigali.
(c) ICT use in Business
(i) Mobile banking and financial services:
Mobile service providers have introduced money transfer and other financial services.
(ii) Village banking: Banks are using telecommunication facilities to provide banking services in remote areas.
(iii) E-business: ICT is a great medium of transacting businesses. Through electronic payment systems such as credit cards and online banking, clients are able to transact business across borders without moving physically from one location to another. Online advertising platforms allow businesses to create awareness about their products.
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(iv) Market survey: Rwandans have real time updates about the Stock Exchange daily market status. This enables them to make informed decisions about regarding investments.
(v) E-Soko: This project enables farmers to make informed market pricing decisions on their produces.
(d) Communication
(i) Video Conferencing: This refers to communication between individuals in different locations by use of simultaneous two-way audio and video transmissions. The users are able to communicate with each other as though they were in the same room. In this way conversations are facilitated. Video conferencing can be used to:
(a) provide a platform to work with others across a distance;
(b) facilitate distance learning;
(c) interview employees remotely; and
(d) facilitate TV broadcasting where a reporter in the field interacts live with the news anchor.
For example, all local government leaders from all districts are able to interact with the minister of local government through video conferencing technology.
(ii) E-mail: E-mail stands for Electronic Mail. It is a method of exchanging typed messages and attachments electronically between individuals. It is used in Rwanda to communicate with employees, customers, friends, and family. It has enabled people to communicate with others outside Rwanda. Examples of e-mail software include Yahoo! mail, gmail, and hotmail. Some benefits of email are:
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(a) It allows individuals and groups to communicate with one another efficiently.
(b) It allows for affordable communication since envelopes and stamps are not needed
(c) It is convenient since the user does not have to go to the post office to send or receive mails.
(iii) Telecommuting: Telecommuting is working from a remote location, usually one’s home by electronically linking to the workplace. The link involves use of various telecommunications technologies such as the telephone, the fax machine, or the Internet. Video conferencing facilities can also be used. Telecommuting is also known as teleworking. The following are some benefits of telecommuting:
(a) It reduces congestion in the roads during rush hour.
(b) It reduces the costs involved in commuting such as bus fare.
(c) It is also a cost-effective way of hiring temporary workers. A temporary worker has therefore the flexibility to work on different assignments and at flexible time.
(iv) Internet: The following are some of the application areas of the Internet:
• Research: Internet has a lot of information which can be used for research materials. For example, sites such as www.kidsclick.org can be used for research.
• Library: The Internet has enabled libraries to be accessed from anywhere at any time. An example of an online library is www.memphislibrary.org.
• Online Books: Internet has enabled the availability of books online. A book can be accessed easily by many readers. An example of an online book site is www. magickeys.com/books.
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• Socializing: The Internet enables the creation of social network services that develop online communities of people who have common interests and activities. Examples of sites are www.fanlala.com and www.facebook.com.
1. Differentiate between verbal and non-verbal communication.
2. Define a tablet as used in ICT.
3. State any three application areas of the Internet.
4. Explain the impact of ICT in the business sector of Rwanda.
5. Explain how each of the following affects the quality of information:
(a) Age
(b) Accuracy
(c) Completeness
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Key Unit CompetencyBy the end of this chapter, you should be able to explain the evolution, categories, parts and roles of computers.
Learning Objectives
Knowledge and understanding
By the end of this unit, you should be able to:
(i) Explain computer- related terms.
(ii) Identify the different parts, functions, and characteristics of a computer.
(iii) Identify different ports and connectors.
(iv) Explain computer inventions and its generations.
(v) Identify advantages, disadvantages and areas where computers are used.
Skills
By the end of this unit, you should be able to:
(i) Use ICT-related terms appropriately.
(ii) Convert from one unit of storage measurements to another.
(iii) Connect different ports to their corresponding connectors.
(iv) Differentiate computer systems and computer parts.
(v) Explain the invention and evolution of computers.
(vi) Differentiate technologies used in different generations of computers.
(vii) Analyse advantages and disadvantages of different generations and areas of computer use.
Attitudes and values
By the end of this unit, you should be able to:
(i) Appreciate the role played by computers in the evolution of society and their impacts on our daily life. (ii) Appreciate how different technological advances have impacted on the evolution of computers.
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Definition of a Computer
A computer is an electronic device that accepts data, processes it using a set of instructions, stores it, and gives information as the output.
Functions of Computers
Computers perform four major operations or functions namely: input, processing, storage, and output.
• Input: This is data entered into a computer for processing. A computer has input devices that are used for data entry. It accepts the data entered into it.
• Processing: This is the conversion of data into information. Once data is accepted, the computer takes it to the processing unit where it is converted into information based on the instructions given by the user • Output: It is the information produced after processing of data is complete. This information can be used as data in another stage or it could be the last result required.
• Storage: A computer can store a large amount of data within it. It has primary and secondary storage devices that are used for this purpose.
Characteristics of a Computer
The following are some characteristics of a computer:
(i) Speed: A computer can carry out processing of instructions at a very high speed. It can perform in a few seconds the amount of work that a human being can do within a long period. The speed of computer is calculated in Hertz (Hz).
(ii) Accuracy: Computers are very precise in processing data as long as they are fed with correct data and instructions.
(iii) Versatility: A computer can perform more than one task at the same time. This is called multi-tasking.
(iv) Reliability: A computer is highly reliable as long as it is fed with accurate data reliability.
(v) Power of Remembering: A computer can store and re-produce information any time because of its large secondary storage space.
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(vi) No Intelligence Quotient (IQ): A computer posseses no intelligence of its own. It can only perform what it is programmed to do. Hence, the user must provide it with accurate instructions. There is a phenomenon called Garbage In Garbage Out (GIGO). If the data fed into the computer does not make sense, the output will also not make sense to the user.
(vii) Diligence: A computer is a machine and therefore it does not suffer from human traits such as tiredness, bad attitudes, and mood swings among others. It also does not lose concentration after working continuously for a long time. Hence computers can do the same tasks over and over again without getting tired. It can also perform long and complex calculations with same speed and accuracy from the start until the end.
(viii) Storage: Depending on the size of its memory, a computer can hold tremendous amount of data. It also has a variety of removable storage locations that could be used to back-up data.
Computer Components
A computer system is a collection of components. These work together to process data and manage information in a computer in order to achieve a desired goal. The components that make up a computer system include hardware, software, and liveware (user).
Hardware
Hardware refers to any physical or tangible component of a computer. It could either be mechanical or electronic. Examples of computer hardware include the Central Processing Unit (CPU), computer peripherals, storage media, ports, and connectors.
The Central Processing Unit (CPU)
The CPU is also known as the processor. It is commonly referred to as the “brain” of a computer system. The processor is a programmable device that controls the retrieval, interpretation, and execution of instructions in a computer. It consists of three components namely:
(i) The Arithmetic and Logic Unit (ALU)
(ii) The Control Unit (CU)
(iii) The storage units, namely the registers and cache memory.
The Arithmetic and Logic Unit (ALU)
It is the part of the CPU that performs two main functions, namely:
• The arithmetic operations such as addition (+), subtraction (–), division (÷), and multiplication (×).
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• The logical operations such as OR, AND, and NOT among others.
The Control Unit (CU)
It is the part of the CPU that coordinates the activities of different sections of the processor and input/output (I/O) devices. It also performs the following activities:
• Controls, supervises, and oversees all the activities of the computer.
• Fetches instructions from the main memory.
• Decodes the instructions in a format the computer can understand.
• Executes the instructions by issuing commands to respective components where action is supposed to be taken.
• Determines the next task to be taken up by the processor for execution.
• Takes the processed instructions to the main memory.
• Controls the transfer of data and information within the available storage space. The above functions can be summarized in what is regarded to as Fetch-Execute Cycle.
readable format, then carries out the execution of the instruction.Storage Units
There are two main storage units found in the CPU, namely Registers and cache memory.
(a) Registers: They are temporary storage locations found inside the processor that are used to hold data, instructions or information awaiting processing or output. There are four types of registers namely: instruction register, accumulator register, address register, and storage register.
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• Instruction register: It temporarily holds an instruction before it is converted to machine readable format. • Address register: It temporarily stores the address of the next instruction to be processed.
• Accumulator register: It temporarily holds the last processing step of the Arithmetic Logic Unit (ALU).
• Storage register: It temporarily holds information waiting to be output.
(b) Cache memory: This is a high speed storage location that enables the CPU to perform its functions faster. It stores frequently accessed instructions so that the CPU can quickly fetch it when needed.
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Computer Peripherals
Peripheral devices are computer components that are connected to the ports in the system unit through cables or wireless media. They include input devices and output devices.
Input devices
These are hardware components that are used to enter data and instructions into a computer. They are classified into:
(i) Keying devices
(ii) Pointing devices
(iii) Scanning devices
(iv) Voice input devices
(i) Keying devices
These are input devices that enable entry of data into the computer through the use of a set of keys. These devices are used for typing letters, numbers, symbols, and commands by pressing a key or combination of keys. Examples are the keyboard and the keypad.
The Keyboard: The keyboard is used for typing letters, numbers and special symbols. It is sometimes referred to as the alphanumeric keyboard. Examples of keyboards are the traditional, flexible, Braille, and ergonomic keyboards.
(i) Traditional Keyboard: They are large and rigid keyboards. They are named based on the arrangement of the first six characters in the first row of the alphabet keys. They include QWERTY keyboards, AZERTY, QWERTZ, and HCESAR.
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(ii) Ergonomic Keyboard: This is designed to minimize wrist injury. It is connected to the system unit using the Universal Serial Bus (USB) cable. Some ergonomic keyboards are split.
(iii) Flexible Keyboard: This is a portable keyboard which can be folded and carried in a bag.
(iv) Braille Keyboard: This is specifically designed for the visually impaired. The keys have raised dots enabling the user to feel and identify the character or symbol represented by the key.
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The Keypad: This is a small keyboard, which is mostly used on devices such as palmtops, calculator, microwaves and washing machines among others.
(ii) Pointing devices
These are devices which control the movement of a cursor or a pointer on the computer screen to select icons or commands. Examples of these devices are the mouse, trackball, joystick, touch screen, light pen, touch pad and graphic tablet among others.
Mouse: It is a pointing device with sensors on the bottom. The sensors enable the user to execute commands, select options, and move a pointer on the screen when the mouse is moved. There are three types of computer mouse, namely a mechanical mouse, an optical mouse, and a wireless mouse.
• Mechanical mouse: It contains a ball underneath which is rotated when the mouse is moved hence controlling a pointer on the screen.
• Optical mouse: It uses digital image processing technology to track the position of the mouse and translate that to position the cursor or the pointer on the screen. It includes a tiny camera that is able to take up to 1,500 pictures per second.
• Wireless mouse: It does not use cables. It uses infrared and radio waves such as Bluetooth to control the pointer on the screen. For a computer to use this kind of mouse, it must also have the infrared or radio wave technology activated.
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Mouse Actions
The following are some of the mouse actions:
(a) Clicking: This is pressing and releasing the left mouse button once. It is used when selecting an item.
(b) Double-clicking: This is pressing and releasing the left mouse button twice in quick succession. It is used when opening a file/a folder, or starting a program.
(c) Right-clicking: This is pressing and clicking the right mouse once. It is used to display the content menu.
(d) Drag and drop: It is pressing and holding down the left mouse button on an item. The mouse is then dragged to the desired location and the button released inorder to move an item.
• Trackball: It is a pointing device with a ball on the top that is rotated with the finger preferably the thumb, or the palm of the user’s hand to control the pointer on the screen. Unlike a mouse, a trackball does not need a mouse pad or a smooth surface underneath it to operate. A track ball has the left and the right button just like a mouse that is clicked to perform an action.
• Joystick: It is a device that looks like a gear lever used to control the movement of the pointer or some objects on the screen. It is mainly used for playing games. A joystick can contain more than three buttons for further manipulation of the object when playing computer games.
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Light pen
It is a hand-held input device that utilizes a light sensitive detector to select objects or to write on the screen. It contains sensors at its tip that send signals to the computer whenever light is recorded. They are often used in design and can also be used for sensing information on magnetic bars and stripes.
Touch screen
It is an input device designed to recognize the location of a touch on its surface. The user can make a selection or move a cursor by touching the screen with the finger.
Touch pad
It is a pointing device commonly found in laptops where the user places or moves the finger across it to control the pointer on the screen. It contains two buttons that are clicked once the desired location is reached in order to execute an action.
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Graphics Tablet or Digitizer
It is a pointing device used by designers and artists. They use it to draw a picture on a computer screen by free hand without using a mouse or a keyboard. It consists of a flat, a touch-sensitive pad and some sort of drawing device, such as a stylus. A stylus is a pen-like device moved over the surface of the tablet. Data about the stylus movements are sent to the computer.
(iii) Scanning devices
They are also known as scanners. They are peripheral components that capture data from the source directly to the computer by converting it into digital format. The source can either be a paper or an object. There are two main types of scanners which include optical scanners and magnetic scanners.
(i) Optical Scanners:
These scanners capture data using light technology. Light is passed over the object or paper to capture the image. The image is then analyzed by specialized software. Examples of Optical scanners are the Optical Barcode Recognition (OBR), the Optical Mark Recognition (OMR) and the Optical Character Recognition (OCR).
Optical Barcode Recognition (OBR): They are also known as Optical Barcode Readers. A barcode is a series of printed parallel vertical lines that differ in thickness and spacing. A barcode contains information about the item ID number. Once a barcode has been scanned, the computer reads the information stored on the barcode and accesses details about the product from the computer database. There are two types of barcode readers:
• Handheld barcode reader: It is also known as a wand. It is held by hand and passed over the product’s barcodes to read the information.
• Countertop barcode reader: It is permanently fixed on the counter and the product is passed over it to read the information.
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• Optical Mark Recognition (OMR): This technology is used to read marks made using a pencil on a piece of pre-printed paper. The OMR shines light onto the paper and less light is reflected where a pencil mark is made. The marked area is usually darker than the unmarked one, making it easier for OMR to recognize the position of the mark or set of marks on a paper. The computer records the marked position and analyses it to determine the meaning of the data. The marks must however be very clear. They are used in reading shaded area in multiple choice examinations, lottery tickets, and questionnaires with objectivetype questions.
Optical Character Recognition (OCR): Optical character readers consist of a scanner along with special user interactive software. They allow scanning of characters on paper (hardcopy) into a softcopy that is stored in the computer. The softcopy version can be edited or formatted.
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(ii) Magnetic scanners: These scanners capture data written using magnetic ink. Examples of magnetic scanners are the Magnetic Ink Character Reader (MICR) and Magnetic Stripe Reader
Magnetic Ink Character Recognition (MICR): It is a scanner that reads characters printed using special magnetized ink (the ink contains iron particles). The special ink contains information, for example, the bank account details which are usually on the bottom of a cheque. MICR is widely used by banks to authenticate cheques and obtain the information written using magnetic ink on the cheque.
Mobile Card Machine: It is also known as the chip or the pin Reader. It is a device used by bank agents to access bank account details of the customer. A plastic card containing a chip is inserted in a slot. The user then enters his or her Personal Identification Number (PIN).
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Magnetic Stripe Recognition: This reads information coded in a magnetic stripe at the back of a plastic card when the card is swiped through it. They read information held on the stripe which could be a bank account number, the name of the card holder, and the card expiry date. They can also be used to control access to a building by swiping the card through the reader.
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The difference between Magnetic Stripe Card Reader and Mobile Card Machine is that the magnetic stripe card reader reads cards with a magnetic stripe by swiping; while a mobile card machine reads cards with a microchip.
(iv) Voice Input Devices
These are devices used to input data in the form of spoken words into the computer. They can be used to control access into a building or record speeches and music. An example of a voice input device is the microphone.
Output Devices
These are devices used for displaying data and information. They are classified into two categories, namely softcopy output devices and hardcopy output devices.
Hardcopy output devices
These are devices which produce output that is recorded on tangible media such as paper. Examples are printers and plotters.
Printers
A printer is a peripheral device that produces hard copy output. Printers can be broadly classified into impact printers and non-impact printers.
31(a) Impact printers
They print on paper. They apply the striking mechanism. The print head physically strikes an inked ribbon. The ribbon then presses on a paper medium to create the image hence the name impact printer.
Due to the impact made by the print head, impact printers are noisy. Examples of impact printers are daisy wheel, dot-matrix, and drum printers. Impact printers can produce multiple copies of the same document at the same time using carbonated paper.
The following are examples of impact printers:
(i) Daisy wheel printers: These printers got their name from the daisy flower. The wheel has hammer-like structures that resemble the petals of a daisy flower. Each hammer (spoke) on the wheel has a character at the printing head. As the wheel rotates, a selected spoke with the appropriate character bends and prints on the paper as is the case with a typewriter. These printers can only print one character at a time.
(ii) Dot Matrix Printers: The head of this printer consists of pins arranged in a matrix. When a character is to be printed, the printer works by using a set of pins to press an inked ribbon against the paper. When the inked ribbon hits the paper, a dot is left behind. The dots are arranged to form text and image.
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(iii) Drum printers: Characters are raised in a cylindrical drum. Values of all characters are stored in the printer buffer. When a character is to be printed, the printer sends the information to the printer buffer. The printer drum is rotated as the character is printed by striking the hammer. The hammer strikes the ink ribbon and an impression is produced on paper.
(ii) Non-impact printers
They are printers that use thermal or electrostatic principles to produce print on paper. The print head element does not come into contact with the paper; hence they are quiet while printing. They print faster and produce high quality prints compared to impact printers. Their ink is contained either in a toner or cartridge. There are three main types of these printers namely: Inkjet, Laser jet and Thermal printers.
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(i) Inkjet printers: These printers spray little dots of ink on a paper forming the shapes of characters and pictures when printing. They are commonly used for noncommercial purposes. Their initial cost is low but maintenance cost is very high. This is due to the high price of buying a new cartridge and the low number of print-out papers produced per cartridge.
(ii) Laser printers: They use the principle of light to form images on the paper. The printers operate by shinning a laser beam that ionizes some regions on the drum. The toner is sprayed on the drum and it sticks on the ionized regions of the drum. The drum is then pressed onto the sheet of paper and the paper is heated (fused) so that the toner is bound to the paper.
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(iii) Thermal printers: These printers use thermal (heat) technology to produce images on a special paper. The print mechanism is designed to heat the surface of chemically treated paper referred to as thermochromic or thermal paper. When the paper passes over the thermal print head, the coating on the paper turns black due to reaction of the chemical to heat forming the required images on the paper. They are popularly used at Point of Sale (POS) terminals to print receipts.
Plotters
These are special-purpose output devices. They are used to produce high-quality, multicolour documents or large size documents such as charts, maps, architectural drawings, and three-dimensional representations based on commands from a computer. There are two types of plotters, namely drum and flatbed plotters.
(i) Drum plotters: In this type, the paper is mounted on the surface of the drum in the plotter. Automated pens are placed horizontally slightly above the paper. As the drum revolves and the part of paper to be plotted comes into alignment with the pens, the pens are activated to create the image.
(ii) Flatbed plotters: In this type, the paper is fixed on a flat surface and pens are moved to create the image. This plotter works by using an arm that moves a pen over paper rather than having paper move under the arm as is the case with drum plotter. The size of the plot depends on the size of the plotters bed.
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Soft copy Output Devices
These are devices that produce information that can be seen, listened to, but not tangible. Examples of soft copy output devices are monitors, projectors, and speakers.
Monitors
A monitor is also referred to as Video Display Unit (VDU) or the screen. It is used to display data and information. There are two main types of monitors, namely the Cathode Ray Tube (CRT) and flat screens.
1. Cathode Ray Tube (CRT) Monitors: They are bulky and heavy. They produce an image (made up of tiny dots) by firing electron beams against a phosphor screen. Each dot is coloured red, green, and blue of different intensities combining to create millions of different colour shades.
2. Flat screens: These monitors are becoming popular nowadays and are used in desktop and laptop computers. They are all characterized by the flat shape which makes them to be lighter, less bulky, and they consume less power than the CRT
Types of Flat screen monitors
• Liquid Crystal Display (LCD) Monitor: The monitor consists of two polarizing transparent plates and a liquid crystal solution in between them. When an electric current passes through the Liquid, the crystals are aligned to form so that light cannot pass through them. Individual crystal acts like a shutter, either blocking the light or allowing light to pass through.
• Thin Film Transistor (TFT) Monitor: This is made up of thousands of small pixels. Each pixel consists of three transistors which are red, green, and blue. Each transistor can produce different intensities of light which allow huge amounts of colors to be produced.
A back light is used to shine light onto these pixels to enable the colors to be produced.
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In order to light a single pixel, tiny windows can be opened and closed to allow the light to pass through and onto the pixel.
• Gas Plasma Display (GPD) monitor: It is a thin display screen. It works by enclosing neon gas between two plates where each plate is coated with a conductive print. The print on one plate contains horizontal conductive lines and the other plate vertical lines. The two plates form a grid and when electric current is passed through the horizontal and vertical lines, the gas at the intersection glows, creating a pixel. A gas-plasma display can be viewed as a collection of very small neon bulbs.
• Electroluminescent Display (ELD) Monitor: This is an optical and electrical phenomenon where a material emits light in response to an electric current passed through it. These monitors refer to a type of display created by sandwiching a layer of electroluminescent material such as Gallium Arsenide (GaAs) between two layers of conductors. When an electric current is passed through a grid, the Gallium Arsenide film at the intersection glows, creating a point of light, or pixel hence an image is created.
Fig. 2.33: Flat screens are all characterized by the flat shape which makes them lighter.
Speakers or Voice Output devices
These are devices that convert electronic signals from the computer into audible sounds. This is achieved through the use of transducers such as speakers. A transducer is a device that converts energy from one form to another.
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Projector
It is a device that uses light and lenses to take an image, magnify it, and project it onto a larger screen or a wall. They can magnify still or moving images depending on how they are built. The image must be shown through a sealed tube or frame when passing through the lenses to maintain focus. They are available in different kinds, namely digital/movie, portable, and overhead projectors among others.
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Ports and Connectors
A port is an interface on a computer on which a device can be connected. A connector is a part of a cable that plugs into a port or interface to connect two devices. Connectors can either be male (containing one or more exposed pins) or female (containing holes into which the male connector can be inserted).
Types of ports
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Storage
Storage Devices and Media
These are devices that are used for storing data, information, and instructions. They are divided into three categories, namely primary memory, secondary memory/mass storage, and tertiary storage.
(a) Primary Memory
Primary memory refers to the computer’s memory, which connects directly to the computer’s CPU. It is also known as main memory. There are two types of main memory, namely Random Access Memory (RAM) and Random Only Memory (ROM).
Random Access Memory (RAM)
This is a memory in the form of integrated circuits (IC). It is mounted on a printed circuit board as modules and designed for use in computing devices. The contents of this memory can be accessed randomly and hence the name “Random Access Memory”.
RAM is a volatile memory. This means that the contents in it are lost when power is switched off. It holds data temporarily before and after processing; and also holds all the programs currently running together with the data being used by the programs.
Read Only Memory (ROM)
The ROM is a non-volatile memory. This means that the content in it is not lost when power is switched off. The content in ROM can be read but cannot be changed. It is intended for permanent or semi-permanent storage of data necessary for the operation of a computer system.
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(i) Programmable Read Only Memory (PROM) is a ROM that allows the user
to alter it only once after the content is written on it.(ii) Erasable Programmable Read Only Memory (EPROM): Eprom is a Read Only Memory whose contents can be erased and can be reprogrammed again.
(iii) Electrically Erased Programmable Read Only Memory (EEPROM): It is a type of ROM that can be erased and programmed again using electricity. for example, BIOS for storing Basic Input Output System (BIOS).
(b) Secondary Memory/Mass Memory
The computer’s main memory is always limited in terms of permanency and capacity. As a result, there is a need for having an alternative storage. The secondary storage devices provide an alternative long-term storage of data, information and programs. These devices can be classified according to portability, as either removable or fixed storage devices.
(i) Removable storage media
They are called removable storage media because they require either a USB port or an external drive connected to the motherboard using a cable. Examples are magnetic tapes, CD/DVD disk, Jaz disk, Zip disk and floppy disk among others. The units for measuring storage capacity is bytes, kilobytes (KB), megabytes (MB), gigabytes (GB), and terabytes (TB).
• CD/DVD disk: They use laser beam of light for reading and writing data.
Compact Disk (CD): This is a hard plastic disk on which information such as music or computer data is digitally encoded in a format readable by a laser beam. The storage capacity of a CD ranges between 650 MB and 700 MB. They are available in three forms: Compact Disk Read Only Memory (CD-ROM), Compact Disk Recordable (CD-R), Compact Disk Read/Write (CD-RW).
CD-ROM: Data can only be read from it but not written to it. This media helps in ensuring that data is not deleted or amended once written and they are popularly used in distribution of software and music among other types of data.
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CD-R: Once data has been burned on it, it cannot be erased but more data can be added on the empty tracks.
CD-RW: These compact disks allow the user to record, erase and rewrite new information as many times as desired.
VCD (Video Compact Disk): It is a Compact disk format based on CD-ROM extended architecture which is a variation of CD ROM that outlines two new types of sector that enables it to read and view graphics, data, audio and video at the same time. It is specifically designed to hold MPEG (Moving Pictures Experts Group) video data and to include interactive capabilities. They come in different variations that include; VCD 2.0, VCD-ROM and VCD/CD ROM among others.
• DVD (Digital Versatile Disk): They are also known as Digital Video Disks. They are optical media used for storing digital data. They resemble CDs but have a higher capacity than the CD. They can hold a minimum of 4.7GB of data. They are commonly used for storing movies and other multimedia presentations that combine sound and graphics. Examples of DVDs are DVD-ROM, DVD-R, DVD- RW and Blu-Ray.
DVD-ROM (Digital Versatile Disk - Read Only Memory): In this media, once data has been written, it cannot be erased or modified but it can only be read.
DVD-R (Digital Versatile Disk-Record able): Once data has been burned on it, it cannot be erased, it becomes read only. ® DVD-RW (Digital Versatile Disk-Re writable): They allow the user to record, erase, amend, and rewrite new information.
Blu-Ray: It is a high definition DVD format that is intended to replace the current range of DVDs. It is used for distributing large amount of material such as movies. The capacities range from 25 GB to 128 GB.
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• USB Flash memory: They are also known as the memory stick (mem stick). Their capacity ranges between 1 GB and 16 GB.
• Memory cards: They are used in digital cameras and mobile phones for storing or transferring data from a device to another. They are inserted in a special slot for data reading and writing. Their capacity ranges between 1 GB and 16 GB
(ii) Fixed storage media They are known as fixed storage media because they are mounted on the computer motherboard and are housed inside the computer system unit. An example is the hard disk
Hard disk: A hard disk consists of one or several inflexible circular disks called platters which are coated with a magnetic material normally Iron II Oxide. On each platter data is stored on tracks that are concentric. These platters are held vertically above each other by a spindle to form cylinders. The platter(s), read/write heads and the mechanisms of moving the heads across the surface of the disk are sealed permanently in an airtight metallic casing to protect the assembly from damage.
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Tertiary Storage
The main purpose of tertiary computer storage is to store data on a very large scale. This includes optical jukeboxes and tape libraries. They require a database to organize the data stored in them. The computer needs to go through the database to access the data.
Assignment 2.3
1. A storage device has a maximum storage capacity of 1.44MB. How many characters can be stored in this device given that 1 character = 1 byte.
2. State two characteristics of primary memory. 3. Define the term port.
4. Identify and draw the symbols of the following ports:
(i) PS/2 for keyboard
(ii) Parallel port
(iii) Monitor port 5. Differentiate between parallel port and serial port
6. Describe the structure of a hard disk.
7. State two differences between Compact Disk and Digital Versatile Disk.
Learning Activity 2C
1. In groups, discuss the following:
(i) The various types of storage devices and their functions.
(ii) The storage capacity for each storage device.
(iii) The advantage and disadvantage of each of the storage devices
2. Observe physically the storage devices available in the computer room.
3. With the assistance of the teacher, watch video or digital images of the storage devices.
4. Connect the various peripheral devices to their respective ports and then unplug them.
5. Name all the ports that are female in the system unit and those that are male.
6. Draw the symbols found in each port in the system unit.
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Software
Definition of software
Software is abbreviated as SW or S/W. It refers to a set of instructions that either enable the computer hardware to perform its assigned tasks or help the user to accomplish specific tasks. Software is also referred to as programs.
Classification of Computer Software
Computer software can be categorized in two different classes, namely System Software and Application Software
System software: They are software designed to manage computer resources and provide these resources to the user. There are five types of system software namely: Operating system, Utility software, Firmware, Programming languages and Networking software
1. Operating System (OS): This is a group of programs that provide a platform for loading other programs known as application programs. The OS acts as an interface between the hardware and the application programs. Part of the operating system resides on the computer memory. When the computer is booted, the OS manages all the input, output and storage operations of a computer. Examples of operating systems include Linux, Ms DOS, MS Windows, OS X, iOS, Android, and UNIX.
2. Utility software: They are system software that are used to perform routine functions aimed at optimizing, analysing, and maintaining the operations of a computer. They manage computer files, diagnose, repair computer problems and help the computer to run more efficiently. Most utility programs are integrated within the operating systems. However, some utility software are bought as a single package. Examples of utility software include Anti-virus, Disk cleaners, Disk Checkers, Disk Compressors, Disk Defragmenter, Disk partitioners, File managers, language translators, graphic editors, and text editors.
3. Firmware: They are sometimes referred to as stored logic. These are software programs that are stored in the computer’s Read Only Memory (ROM), where they are available for immediate use. They are hard–coded; this means that they are fixed in such a way that the code cannot be changed without modifying the program. They are stored in a silicon chip and therefore are not affected by loss of power, hence the term firm. An example of firmware is Basic Input Output System (BIOS). Firmware may hold utility programs, language processors, or even operating systems.
4. Programming Language Software: These are formal constructed languages designed to communicate instructions to a computer. They are used to create programs that control the operations of a machine. They have language translators integrated in them.
5. Networking Software: It is a system software that is used for configuration and enhancement of interactions in a computer network. They enable exchange of data. They also have security features that protect the network from malfunctioning. Networking software features are nowadays incorporated in most of the general operating systems. Examples include Linux, UNIX, MS-Windows 7, MS-Windows XP, and MS Windows 8 among others. However, some of these software come as independent software, for example, MS Windows server 2000, MS Windows server 2003, Sun Solaris, MS Windows NT, and Novel Netware among others.
Application software: They are programs that are designed to enable the user to accomplish a given task. There are three groups of application software, namely customised software and off-the-shelf software.
1. Customised Software: They are also known as in-house developed software. They are tailor-made to solve a specific problem at hand, or to meet a specific need of the user. For example, programs used in a point of sale terminal are usually customised. The user may decide to outsource or employ a programmer to design the program.
Advantages of customised software
(i) They only contain features that are required by the user.
(ii) The can be modified any time at the user’s request.
(iii) They are tailor-made to solve a specific problem for the user.
Disadvantages of customised software
(i) They are expensive to acquire.
(ii) They are not readily available.
2. Off-the-Shelf software: They are also known as standard software. They are software written by a software engineer or a programmer, packaged, and then made available through a vendor, a distributor, or a developer. Examples include the general purpose software.
Advantages of off-the-shelf software
(i) They are cheaper than in-house developed software.
(ii) They are readily available in the market.
(iii) They are robust; this means that they have been thoroughly tested and hence they work with minimal or no error
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.Disadvantages of off-the-shelf software
(i) They may contain extra features that are not required by the user; hence occupying unnecessary space in memory
(ii) They may lack certain features that are needed by the user; hence failing to fully solve the problem at hand.
Note: The developer can decide to put single software or a group of software that are closely related into one package. The software, packaged in groups, are known as either a suite or integrated software.
(a) Integrated Software: These are software that combine several standard software into a package. Examples of integrated software include Microsoft (MS) Office, Corel Office, Lotus SmartSuite, Open Office, iWork package, and Libre Office.
(b) General-purpose software: They are software written to solve no particular problem. They can be used to solve a variety of problems depending on how they are applied. Examples include: Word processors, Spreadsheets, Desktop publishing, Databases, Computer Aided Design (CAD).
Assignment 2.4
1. Define the term software.
2. Differentiate between an application software and a system software.
3. Explain three types of system software.
4. Define the term firmware.
5. State two differences between high level and low level programming languages.
6. State two roles of an operating system.
7. State three advantages of general purpose software.
8. Categorise the following software as either application or system software.
(i) Sugar
(ii) Antivirus
(iii) Scratch
(iv) Word processor
9. State two characteristics of integrated software.
Learning Activity 2D
In groups, discuss the following:
(i) List examples of operating systems.
(ii) Identify the various types of utility software and state their functions.
(iii) Identify the various types of application software and categorise them as either customised or off-the-shelf software.
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Computer Family
• The term computer family refers to category of computers with the same operational design and microprocessors that are compatible with each other. Examples of computer families are the IBM or PC versus the Apple or the Mac family. Computers in these families can be classified as Microcomputers, Minicomputers, Mainframe and Supercomputers.
1. Microcomputers
They are popularly known as Personal Computers (PCs). They are designed to be used by one person at a time. They are the smallest, cheapest, and most portable. They are commonly used in offices, for training, entertainment, communication, business enterprises, and in homes among other places. Examples of microcomputers are desktops, laptops, tablets, and Personal Digital Assistants (PDAs) or palmtops.
• Desktop computers: These are computers designed to be used while placed on top of a desk or a table. They cannot be powered from an internal battery and therefore must remain connected to a wall power outlet. They are used in offices, in businesses among others.
• Laptop computers: These are portable computers. They have all input/output, processing and memory devices inside the system unit. This leaves only a few external accessories to be connected to the ports. These computers are designed to be used while placed on the user’s lap. They are used in schools.
• Tablets: These are small, portable computing devices, similar to a notebook. They are primarily used for Internet access and email. They come with limited features and are relatively cheaper and much lighter compared to laptops. They used for internet access.
Note: The main differences between a notebook and a laptop are:
A laptop has more ports and other plug-in options to allow for connection of additional peripherals compared to a notebook.
A laptop has both the USB port and an inbuilt Digital Versatile/ Compact Disk drive whereas a notebook only contains the USB port.
• Palmtops: They are also referred to as handheld computers, or PDAs. They are designed to fit in the palm of the hand and easily fit in a pocket. Due to their small size, they do not have disk drives. However, many contain Personal Computer Memory Card International Association (PCMCIA) slots for expansion of memory and insertion of disk drives and MODEMs among others. They are commonly used in communication.
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2. Minicomputers
They are also referred to as mid-range computers. They are small in size and cheaper. They have a low processing speed compared to super and mainframe computers. Their storage capacity is higher than that of microcomputers. They are popularly used to computerize processes in manufacturing industries and production lines, as well as in autopilots in aeroplanes. They are also used as servers in large and medium-sized organizations.
3. Mainframe computers They are the second largest in physical size. They are very large and expensive. They are capable of supporting thousands of users in a computer network simultaneously. They mostly use operating systems which are based on UNIX and Linux. Mainframes are used for centralized processing, for example, in large commercial organizations such as government agencies, banks, hospitals, airlines, manufacturing companies, and telecommunication agencies among others.
3. Supercomputers They are the largest in size, fastest, most powerful and most expensive computers. Supercomputers are used to process large amounts of data at very high speed and they
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solve problems requiring complex calculations within a fraction of a second. Due to their large size and weight, they are not portable and are housed in a special room that has special cooling system. These computers are mainly applied in scientific research work, for example, in weather forecasting, advanced military applications, and mobile phone economy among others.
Assignment 2.5
1. Describe three types of microcomputers.
2. State two differences between super computers and mainframe computers.
3. Mention two application areas of supercomputers.
4. Describe minicomputers.
5. State two differences between a notebook and a laptop.
Learning Activity 2E
1. In groups, discuss the following:
(i) The emergence of new microcomputer devices and how they are used.
(ii) Discuss whether a supercomputer uses analog or digital technologies.
2. Observe physically some computer family available in the school computer room.
3. With the assistance of the teacher, watch video or digital images of the various computer families.
History (Evolution) of Computers
The evolution of a computer has taken many years and it exists out of inventions by different scientists. The following tools have been invented over time leading to the development of current computers:
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(a) Abacus: It was the earliest counting tool used by Babylonians in around 300 BC. They later became associated with Chinese more than 2,000 years ago.
(b) Napier’s Bones: A Scottish mathematician known as John Napier developed mathematical logarithms in 1614. He subsequently invented Napier’s Bones in 1617 that was used for calculations. It could multiply, divide, and calculate square roots, as well as cube roots.
(c) Slide rule: An English man William Ought red used the logarithms idea to develop the slide rule in the 1620’s which was used for calculations
(d) Pascaline/Mechanical Calculator: The French mathematician, Blaise Pascal, invented the first mechanical calculator or calculating machine in 1642. It could add and subtract numbers; hence helped his father who was a tax collector.
(e) Jacquard Loom: It was a mechanical weaving machine invented by Joseph Marie Jacquard in 1801. This was the first machine controlled by punched cards in weaving or manufacturing of textiles.
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(f) Analytical Engine and Difference Engine: Charles Babbage was an English mathematician, a philosopher, an inventor and a mechanical engineer. He initiated the concept of a programmable computer. While Babbage’s machines were mechanical and cumbersome, their basic architecture was similar to a modern computer. He first invented a Difference Engine followed by an Analytical Engine
(i) Difference Engine: This was an automatic mechanical calculating machine. It could perform mathematical calculations commanded by a fixed instruction program. It was invented around 1822.
(ii) Analytical Engine: This machine was a general purpose, fully program controlled, automatic mechanical and digital computer. It had all parts of the present day computers. As a result of his invention, Charles Babbage is referred to as the father of modern-day computers. It was invented around 1832.
The main difference between the Difference Engine and the Analytical Engine is that the Analytical Engine could be programmed using punched cards.
In the 1840’s, a mathematician known as Ada Lovelace developed a program for the Analytical Engine. Based on her work, Lovelace is recognised as the first computer programmer.
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(g) Tabulator:
An American statistician, Herman Hollerith, invented a tabulating machine called a Tabulator that was able to apply punched cards to record and sort data. This machine was used to analyse the US census data of 1890. Hollerith founded the Tabulating Machine Company that later became International Machine Company (IBM), and today plays a great part in modern computing.
Mark 1: This was the first computer-like machine that was developed by IBM and Howard Aiken of Harvard University in 1937. It weighed about 4,500kg. It was 16m in length and 2.4m in height. It became operational in the mid-1940s’. Since then, there was a rapid advancement in computing that is commonly
known as Generations of Computers.
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Generations of Computers
First Generation Computers (1940’s to mid-1950’s)
The following are the characteristics of the First Generation computers: (i) They used vacuum tubes or thermionic valves technology for amplification and as switching devices. A thermionic valve is an electronic valve in which electrons are emitted from a heated cathode.
(ii) These computers used the machine language for programming.
(iii) They used magnetic drums for internal memory.
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(iv) Punched cards were used for data input
(v) The output was given in form of printouts. Some examples of computers in the First Generation are: Electronic Discrete Variable Automatic Computer (EDVAC), Universal Automatic Computer (UNIVAC), Electronic Numerical Integrator and Calculator (ENIAC) and Mark 1.
Disadvantages of the First Generation Computers
(i) The vacuum tubes were huge.
They, therefore, made the computers heavy and bulky.
(ii) They consumed a lot of electrical power.
(iii) They generated a lot of heat.
This resulted in frequent breakdowns.
Second Generation Computers (mid 1950’s to early 1960’s)
The following are the characteristics of the Second Generation computers.
(i) They used transistor technology. A transistor is a semiconductor device with three terminals. It allows amplification and switching of signals.
(ii) They used the magnetic core for internal memory
(iii) The magnetic tape was introduced as a secondary memory.
(iv) The assembly language was used for programming.
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(v) They used punched cards for input of data.
(vi) Printouts were used for output of information. Some examples of computers in the Second Generation are: Honeywell 1800, IBM140 and IBM 709.
Advantages of Second Generation computers
Compared to the First Generation computers:
(i) they were smaller due to the use of transistors;
(ii) they produced less heat; and
(iii) they were less prone to hardware failure.
Disadvantages of Second Generation computers
(i) They still produced a lot of heat. They, therefore, required a special cooling system
. (ii) They required frequent maintenance since they easily broke down.
Third Generation Computers (early 1960’s to early 1970’s)
The following are the characteristics of the Third Generation computers:
(i) They used Integrated Circuits (IC’s) technology
.
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(ii) Magnetic disks and magnetic tapes were used for secondary memory.
(iii) Keyboards were used for data input. (iv) Monitors were used for data output.
(v) Common Business Oriented Language (COBOL) and Formula Translator (FOTRAN) programming languages were used for programming. Some examples of computers in this generation are: Burroughs B6500, Honeywell-115 and IBM 360.
Advantages of Third Generation computers
(i) They were smaller and less expensive than the previous two generations.
(ii) They had a higher processing speed and storage capacity compared to the previous generations
(iii) They consumed lesser electrical power compared to the previous generations.
Disadvantages of Third Generation computers
(i) The initial cost was high due to the sophisticated technology required in the development of Integrated Circuits (ICs).
(ii) Air conditioning was required since they still produced a lot of heat.
Fourth Generation Computers (early 1970’sto late 1980’s)
The following are the characteristics of the Fourth Generation computers:
(i) They used Large Scale Integration (LSI) and Very Large Scale Integrated (VLSI) Circuits technology commonly known as Microprocessor.
(ii) Optical disks, magnetic disks, and magnetic tapes were used as secondary memory.
(iii) Virtual memory was introduced. Virtual memory refers to the use of part of the hard disk as main memory for storing tasks held in the processor. Examples of Fourth Generation computers include IBM 370, Macintosh, Apple II and
Honeywell DPS-88.Advantages of the fourth generation computers
(i) They are smaller because of high level of circuit integration; hence they are portable.
(ii) They are cheaper since they are readily available in the market.
(iii) They have very high processing speeds compared to the previous generations.
The Fifth Generation Computers (Early 1990’s to present)
The following are the characteristics of the Fifth Generation computers:
(i) They use parallel architecture and super conductor technology.
(ii) They use Artificial Intelligence (AI). This is the science of developing machines that mimic human behaviour such as reasoning, learning, hearing, seeing, and communicating. Their goal is to have a machine that can use and process natural language, respond to inputs, learn about its surrounding, and organize itself to adapt to the environment. These computers are still under development and further advancement is still going on.
Assignment 2.6
1. Who was known as the father of modern computers? Explain your answer.
2. State two advantages of the Fourth Generation computers.
3. Define the term virtual memory
4. Mention three characteristics of the Third Generation computers.
5. Define the term Artificial Intelligence (AI).
6. State two characteristics of the Second Generation computers.
7. Name the storage device developed in the following computer generations:
(i) 2nd Generation
(ii) 3rd Generation
(iii) 4th Generation
Learning Activity 2E In groups, discuss the following:
(i) The various computer generations.
(ii) The various types of technology used by the various computer generations.
(iii) Speculate the features of a future computer; one that is not yet in existence. What are likely to be its capabilities.
Advantages of a Computer A computer:
(a) Performs tasks faster and more efficiently than a human being.
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(b) Processes the work accurately when correct data is fed into it.
(c) Performs a variety of tasks at the same time and helps the user to solve different problems while at the same time offering entertainment. A user can, for example, play background music while working on other tasks.
(d) Reduces costs: In an automated office environment, a computer is used to perform tasks that would normally be assigned to several officers.
(e) Offers convenient and paperless storage. This saves a company a lot of floor space that would otherwise have been used to store files.
(f) Is automatically programmed to receive instructions. When accurate instructions are fed into a computer, close monitoring of the tasks is not required unlike in the case of manual operations.
Disadvantages of a Computer
(a) A computer cannot reason. It is a machine that is only useful when the installed programs are appropriate for the intended tasks, and also match the skills of the user. This is because it takes in whatever data is fed into it, whether correct or wrong and processes the same. This phenomenon is described as Garbage in Garbage out (GIGO). It is, therefore, upon the user to verify the accuracy of the data entered.
(b) Using computers can lead to some health problems, especially if not properly used. Some of the health risks include eye problems, backache, and wrist injuries.
(c) Computers are expensive to acquire. If they are not taken care of, they can break down easily since they are vulnerable to dust and other environmental factors.
(d) Computers and automation can lead to loss of jobs, especially for computer illiterate persons.
Areas Where Computers are used
The use of computer technology has reduced the world to be one small village, also known as the global village.
1. Use of Computers in the Communication Industry
The emergence of telecommunication and computing technologies has led to the development of cell phones and computers. These have enabled people even in remote areas to communicate easily. Cell phones are being used to send and receive short messages through the Short Message Service (SMS).
Cell phones are used to connect to social sites and make voice calls anywhere on the globe.Through the Internet, using electronic mail (e-mail) people can send messages (mails) to their friends and relatives living anywhere in the world cheaply and faster.
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Computers and technology generally have enabled the generation of digital content leading to high quality signals for television and radio transmission.
2. Use of Computers in the Business Industry It is possible to buy a goods and services from anywhere on the globe while in the comfort of one’s office or home. This is done through electronic commerce (eCommerce) which involves selling and buying of goods and services through the Internet. For businesses that have embraced technology, they have improved their levels of customer service. They offer fast, reliable, and more efficient services, hence gaining competitive edge over their business rivals. Computers allow businesses to create websites, advertise their products, and connect with other businesses by uploading their latest articles, product images, and blog posts. Accounting software allows businesses to input financial data and analyse it to establish their gains and losses. Businesses store data centrally for easy access from multiple computers or stored locally for individual use. Computerized storage saves space and provides a more efficient organization structure.
3. Use of Computers in the Media Sector: Examples include:
• Advertisement companies are also shifting from the mainstream advertisement media to plasma screens that are placed on the streets and in bus stations.
• Digital cameras are used to capture high quality images and pictures which are used in billboards, print media, and broadcasting.
• Television broadcasting has been changed from analog to digital systems.
• News anchors can now use video conferencing in broadcasting.
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• Video conferencing facilities have enabled media personnel to broadcast information from two different countries or locations at the same time.
• Smart boards and tablets are used in news or events reporting.
4. Use of Computers in the Education Sector
The education sector has improved a great deal due to the integration of computers. In this sector, computers are used as an aid in teaching and learning activities. Students are able to register for courses offered outside their country without having to travel abroad. This is referred to as online learning, and it is done through the Internet.
Information technology has also facilitated education through Computer Aided Learning (CAL) and Computer Based Simulation (CBS).
Computer Aided Learning (CAL):
It is also known as Computer Based Training (CBT). This refers to integration of ICT into the learning process. It involves the use of computers in education and training. CAL techniques include:
(a) Educational games: These are electronic games that have content relevant to a subject area. For example the Carmen Sandiego helps students learn world geography.
(b) Problem solving tutorials: These are self-instructional programs that guide the learner through the resource material acting as their virtual teacher.
(c) Drill and practice: A set of questions from a database are given to students repeatedly to practise skills and concepts. The questions usually have straightforward answers and are therefore very easy for the computer to mark.
Computer Based Simulation (CBS): Computer simulation is the modelling of a real life situation using a computer. It can be used to mimic a real learning situation. For example, it can be used to mimic a chemistry experiment.
5. Use of Computers in the Entertainment Industry Desktop computers and portable computers are used for playing games. These games can be downloaded from the Internet or they can be bought from vendors. Disk Jockeys (DJs) use computerized systems to mix and play music. A disk jockey is a person who plays music on radio, TV, and music concerts to provide beats. Computers have made it possible for artists to produce their contents and store it in Video Compact Disks (VCDs), Digital Versatile Disks (DVDs) and audio Compact Disks (CD).
6. Use of Computers in the Medical Field Computers are used in the medical sector to keep records of patients. In the Intensive Care Unit (ICU), computers are used to control life support machines.
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Machines such as Magnetic Resonance Imaging (MRI) scanners are used to generate images of a human body during medical diagnosis. MRI provides good contrast between the different soft tissues of the body making it more useful in imaging the heart, muscles, the brain, and cancer cells compared with other medical imaging techniques such as X-rays.
Patients also receive medical diagnosis and advice from medical experts through the use of computerized expert systems. Doctors can be reached easily through the use of cell phones and electronic mail (e-mail). There are many mobile applications that are used in the medical field. For example, there are applications that are designed to remind patients when to take drugs or go for their clinical appointments.
7. Use of Computers in Security Systems Computers are used by the law enforcers to analyse fingerprints. They are matched to the records contained in their database.
Through this analysis, they are able to identify and arrest the offenders. Security forces also use computer-based face recognition programs and crime scenes analysis to carry out their investigations. This is done through the retrieval and matching of the suspects’ faces with those they have on their security database.
Through the application of special software, they are able to model the person’s facial appearance. This automated method of verifying the identity of a person based on physiological or behavioral characteristics is known as biometrics or biometry. Computer based systems are also being used in tracking down vehicles. For example, when a vehicle has been carjacked, a car tracking system is able to automatically locate it.
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In some cases, the tracking system is able to automatically stop the car and lock the doors until it is recovered. Closed Circuit Television (CCTV) systems are used in buildings, homes, streets and shopping malls to monitor the ongoing activities. CCTV systems are the common method in supermarkets for monitoring for shoplifters. Computerized metal detector machines are also used to ensure that people and cargo, for example, harmful explosives are not delivered into buildings or restricted environments.
8. Use of Computers in Traffic Control Computerized systems can be used to control traffic on roads, oceans and air.
(a) Air traffic control: Aeroplane traffic service is provided by groundbased controllers who direct aircraft on the ground and in the air. They ensure that aircraft take off and land safely at all times. Every airport has its own air traffic control staff that use computer systems to monitor every single flight. At any given time the air traffic staff will know exactly the position of each aircraft for which they are responsible.
(b) Ship traffic control: ICT helps with working out the logistics of shipping by providing a means of monitoring ships efficiently. They help in monitoring ships on the high seas using Geographical Positioning Systems (GPS). Computerised systems also plan the docking, as well as the loading and unloading of cargo. For example, Vessel Traffic Service (VTS) is used for management of traffic and service control.
(c) Automobile traffic control: Computerised systems are used for controlling and coordinating traffic lights. Traffic enforcement cameras are used to detect vehicles which violate traffic rules.
9. Use of Computers in Weather Forecasting Weather forecasting
is the prediction of weather conditions using measurements and observations of the current weather conditions. Weather forecasting sensors and
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instruments collect the data, then send it to computers for storage and analysis. The data is then displayed in user-friendly graphics and animations that are easy to interpret. The following are some of the systems used in weather forecasting.
• Doppler radar: This is a device that uses beams to detect the location of storms, indicate wind direction and speed of wind, and the amount of rainfall, among other weather conditions.
• Weather balloon: It is a special type of high altitude balloon filled with hydrogen or helium. It is fitted with a device called a radiosonde that records weather conditions. The balloon expands as it rises. The device is able to collect information on atmospheric pressure, temperature, humidity and wind speed. When the balloon reaches a point it can no longer expand, it bursts, and launches a parachute that brings back the radiosonde with the weather recordings.
• Satellite: They are used to take pictures that help in the creation of weather maps that show type of clouds and the amount of rainfall. An example of such a satellite is the METEOSAT.10. Use of Computers in Office Work
Computers are used in offices to prepare memos, letters, and reports among others. They can also be used for preparing daily programs for the staff.
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They are also used for the purposes of keeping track of the computer activities carried out by employees. This is done through the use of log file information.
11. Use of Computers for Storage Computers with large storage space are used for storing volumes of files that could otherwise occupy a lot of floor space. It is possible to backup important files in virtual storage sites in what is known as cloud computing. These files can be opened from other locations provided one is connected to the Internet.
12. Use of Computers in the Manufacturing Sector Manufacturers use computerised machines called robots to do jobs that may pose danger to human beings. Robots also help to reduce human labour costs. For example, in car manufacturing industries, robots are used to test the car engines at the early stages of development.
Computers are also used for quality and process control in some companies such as chemical industries. Other industries also use computers for inventory control, as well as preparing and processing cheques.
Revision Exercise 2
1. Explain three types of computer buses.
2. State the function of a register in a computer.
3. With the aid of a diagram, explain the Fetch-Execute Cycle.
4. Give two limitations of a voice input device. 5. Mention two ways in which computers have been modified for use by physically challenged people.
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6. Explain three factors to be considered when purchasing an input device.
7. State the function of cache memory.
8. Differentiate between RAM and ROM.
9. Differentiate between ports and connectors.
10. State two advantages of the USB port.
11. Differentiate between tertiary and secondary storage devices.
12. (a) Define the term integrated software. (b) List two examples of integrated software.
13. State two advantages of off-the-shelf software.
14. A laptop computer is more expensive than a desktop computer of the same specification. State two reasons for this. 15. State two ways in which computers are used in the education sector.
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