Computer Studies SS1 First Term PDF

 ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 1 SSS1 COMPUTER/ DATA PROCESSING FIRST TERM SCHEME OF WORK WEEKS TOPICS SUB-TOPICS...

 ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 1 SSS1 COMPUTER/ DATA PROCESSING FIRST TERM SCHEME OF WORK WEEKS TOPICS SUB-TOPICS/CONTENTS 1. OVERVIEW OF COMPUTER Meaning of Computer System. SYSTEM Basic Operations of a Computer System. Components of a Computer System. Characteristics of a Computer System. 2. COMPUTER HARDWARE AND Meaning of Computer Hardware. SOFTWARE Categories of Computer Hardware. Meaning of Computer Software. Categories of Computer Software. 3. HISTORICAL DEVELOPMENT OF Examples of Early Computing Devices. COMPUTING DEVICES. (PRE- Features of Early Computing Devices. COMPUTER AGE TO 19TH Components of Early Computing Devices. Uses of Early Computing Devices. 4. HISTORICAL DEVELOPMENT OF Features, Components and Uses of ENIAC. COMPUTING DEVICES. (20TH Features, Components and Uses of EDVAC. CENTURY TO DATE) Features, Components and Uses of UNIVAC. Description of Personal Computers. 5. INPUT DEVICES Meaning of Input Devices. Examples of Input Devices. Description of Each Example of Input Device. 6. OUTPUT DEVICES Meaning of Output Devices. Examples of Output Devices. Description of Each Example of Output Device. 7. DATA AND INFORMATION Meaning of Data and Information. Examples of Data and Information. Difference between Data and Information. Sources of Data and Information. 8. BASIC COMPUTER OPERATION Definition of Booting Types of Booting. Description of booting process. Components/Features of Windows Desktop. 9. COMPUTER ETHICS/ HUMAN Meaning of Computer Security. ISSUES Classification of Computer Threats. Reasons for Computer Security. How to Secure Computer Room and Systems. Indebt Analysis of Computer Virus. 10 REVISION 11-12 EXAMINATION  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 2 OVERVIEW OF COMPUTER SYSTEM Objectives: Discuss the meaning of computer system. List and explain the basic operations of a computer system. State and explain the components of a computer system. Outline the characteristics of a computer system. Meaning of a Computer System Definition 1: A Computer is an electronic machine that accept data as input, process the data and produce information as the desirable output with the help of stored program Definition 2: A Computer is an electronic device which under the control of a stored program can accept process, store, retrieve data and output the result as information in a specified form. Definition 3: A Computer is an advanced electronic device that takes raw data as input from the user, processes these data under the control of set of instructions (called program), gives the result (output) and saves output for future use. Definition 4: A Computer can be defined as a programmable electronic device designed for performing prescribed operations on data at high speed. It can also be linked to other devices for inputting, storing, retrieving, and output of information. Basic Operations of the Computer The three basic operations of the computer are; a. Input (Data): Input is the raw data entered into a computer from the input devices. It is the collection of letters, numbers, images etc. b. Process: Process is the operation of data as per given instruction. It is totally internal process of the computer system. c. Output: Output is the processed data given by computer after data processing. The output is known as Information. We can save these results in the storage devices for the future use.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 3 Constituents of a Computer System A system is a set of connected parts forming a complex whole. Therefore, a computer system is a functional unit of interconnected parts or devices working together to achieve a common output. It is made up of the CPU, memory and related electronics (main cabinet), all the peripheral devices connected to it and its operating system. The computer system can be grouped into three namely: a. Computer Hardware b. Computer Software c. Human ware Characteristics of a Computer The following are the major characteristics of a computer, depending on their types and application: a. Speed: A computer works at amazing speed. It can carry out instructions at a very high speed because it uses an electronic signal which runs at the speed of light. It can perform in a few seconds the amount of work that a human being can do in an entire year – if he works day and night and does else. Some calculations that would have taken hours and days to complete otherwise, can be completed in a few seconds using the computer. The speed of computer is calculated in MHz, that is one million instructions per second. b. Accuracy: The accuracy of a computer is consistently high. The degree of accuracy depends on the instructions and the type of processor. It performs operations at fast rate and gives the result of division of any number up to 10 decimal points without errors such that the accuracy is beyond expectation. Since it is programmed, the result can only be wrong if the input is wrong. c. Versatility: This is one of the most wonderful things about computer. Multi-processing features of computer makes it quite versatile in nature. One moment, it is preparing the results of particular examination, the next moment it is busy preparing electricity bills, and in between it may be helping an office secretary to trace an important letter in seconds. It can perform different types of tasks with same ease. All that is required to change its talent is to slip in a new program into it. Briefly, a computer is capable of performing almost any task provided that the task can be reduced to a series of logical steps.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 4 d. Reliability: Computer provide very high speed accompanied by an equality high level for reliability. Thus, computers never make mistakes of their own accord. e. High Storage and Retrieval Capacity: A computer can store and recall any amount of information because of its secondary storage capability. Every piece of information can be retained as long as desired by the user and it can recall information almost instantaneously. Even after several years, the information recalled will be as accurate as on the day when it was fed to the computer. f. Diligence: The computer is a machine, does not suffer from the human traits of tiredness. Nor does it lose concentration even after working continuously for a long time. This characteristic is especially useful for those jobs where same tasks is done again and again. It can perform long and complex calculations with same speed and accuracy from the start till the end. g. Storage: The computers have a lot of a storage devices which can store a tremendous amount of data. Data storage is essential function of the computer. Secondary storage devices like floppy disk can store a large amount of data permanently. h. Automation: Once the instructions are fed into computer it works automatically without any human intervention until the completion of execution of program until it meets logical instructions to terminate the job. Evaluation 1. Define a computer system. 2. List the three basic operations of a computer. 3. State two broad constituents of a computer system. 4. Outline five characteristics of a computer system. 5. List two differences between automation and storage.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 5 COMPUTER HARDWARE AND SOFTWARE Objectives: Discuss the meaning of computer hardware. State and explain the categories of computer hardware. Discuss the meaning of computer software. Outline and explain the categories of computer software. Enumerate the differences between system software and application software. Meaning of Computer Hardware Computer hardware is the collection of physical elements that constitute a computer system. Computer hardware refers to the physical and electronic parts or components of a computer such as monitor, keyboard, hard drive disk, mouse, CPU (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that you can actually touch. Categories of Computer Hardware Computer hardware is divided into two main categories namely: a. System unit, and b. Peripherals The System Unit: This is the electronic components such as CPU, primary memory and other devices that are used to process and store data. It is the computer casing or cabinet that contains the Central Processing Unit (CPU) and many other electronic components. It contains many hardware components that can be seen only when the case or cabinet is open. A Peripheral: This device is any piece of hardware attached to the computer’s system unit to facilitate or enhance input and output operations. Those devices which are not an integral part of the CPU are referred to as peripherals. These attachments increase the capabilities of the computer. Peripherals are usually used for either input, storage, output and communication devices (such as a hard disk, keyboard, printer, modems, digital camera, etc.). Computer hardware can also be categorized as; a. Input Devices: These are hardware devices which take information from the user of the computer system, convert it into electrical signals and transmit it to the processor. The primary function of input devices is to allow humans to interact with the computer system. For instance, a mouse allows the user to control the movement of the pointer (a common element in user interface design).  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 6 b. Output Devices: This takes data from the computer system and convert it to a form that can be interpreted by humans. For instance, a monitor creates a visual electronic display to output information created by the processor to the user. c. Processing Devices: These are the components responsible for the processing of information within the computer system. This includes devices such as the CPU, memory and motherboard. d. Storage Devices: These are components which allow data to be stored within a computer system. This includes devices such as hard disk drives and compact disk drives. Meaning of Computer Software Computer Software (often called just software) is a set of instructions and associated documentation that tells a computer what to do or how to perform a task or it can mean all the software on a computer, including the applications and the operating system It is also a set of instructions (programs) that commands the computer hardware what to do, how to do and as well as when to do. In other words, software is a set of programs, procedures, algorithms and its documentation. It is the driver of the hardware. Without the software, the computer becomes useless and an idle piece of metal. Categories of Computer Software Software as a whole can be divided into a number of categories based on the types of work done by programs. The two primary software categories are; a. System Software b. Application Software System Software This is a collection of computer software designed to operate the computer hardware and to provide and maintain a platform for running application software. Systems software includes the programs that are dedicated to managing the computer itself, such as the operating system, file management utilities, and disk operating system (DOS) which control the workings of the computer. More so, it can be defined as a collection of programs designed to operate, control, and extend the processing capabilities of the computer hardware. System software is generally prepared by the computer manufacturers. These software products comprise of programs written in low-level languages, which interact with the hardware at a very basic level. System software serves as the interface between the hardware and the end users.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 7 Types of System Software Categories of System software includes; a. Operating Systems : This is an operating system is a program that acts as an interface between the software and the computer hardware e.g., windows o/s, Linus o/s, disk operating system, android o/s, Symbian o/s, etc. b. Device Drivers: This is a computer program that operates or controls a particular type of device that is attached to a computer e.g., scanner driver, printer drivers, network drivers, graphics driver, sound card drivers, etc. c. Utility Software: This is designed to help analyze, configure, optimize or maintain a computer. It is used to support the computer infrastructure in contrast to application software, which is aimed at directly performing tasks that benefit ordinary users. Examples are: anti-virus, clipboard managers, disk checkers, disc cleaner, disk defragmenters, file managers, etc. d. Translators: This is a software that converts high level language (human language or source code) to machine language Application Software An application program (app or application for short) is a computer program designed to perform a group of coordinated functions, tasks, or activities for the benefit of the user. It is also known as software application, application or app, consists of programs that instruct the computer to accomplish specific tasks for the user, such as word processing, operating a spreadsheet, managing accounts in inventories, record keeping, or playing a video game. These programs, called applications, are run only when they are needed. The number of available applications is as great as the number of different uses of computers. Some examples of this category of software includes; a. Accounting software e.g., Peachtree Complete Accounting b. Computer-aided design e.g., Corel Draw c. Databases e.g., Microsoft access d. Decision making software e.g., Microsoft project e. Educational software e.g., Microsoft Encarta f. Image editing e.g., Adobe photo-shop g. Mathematical software e.g. SAGE h. Word processor e.g., Microsoft word i. Spreadsheets e.g., Microsoft excel j. Media players and database applications  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 8 Differences between System Software and Application Software S/N System Software Application software 1. Can run independently of the application It cannot run without the presence of the system software software 2. It gets installed when the operating system is It is installed according to the requirements of the installed on the computer user 3. They are programs that run and control the They are programs designed to meet specific needs hardware units of the system of users 4. It provides a platform for running the It helps the user to perform single or multiple tasks application software 5. Some examples of system software are Some examples of application software are computer operating systems like Windows Microsoft Word, Accounting software like XP, Linux, MacOS and Ubuntu Microsoft Excel and Microsoft Access 6. They are intricately(carefully) programmed They are programmed by applications by system programmers or manufacturers programmers. Human ware: This is the combination of hardware and software elements that make human interaction with a device as good as possible. Often, developing human ware begins by defining who the computer's potential users are, what they are interested in, and what they need before designing the infrastructure. Evaluation 1. Define computer hardware and state the two categories. 2. Define computer software and identify the types. 3. Explain the meaning and differences between system software and application Software. 4. List ten examples of an application software.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 9 HISTORICAL DEVELOPMENT OF COMPUTING DEVICES (Pre-Computer Era – Early 19th Century) Objectives: List out the examples of early computing devices. State and explain the features of early computing devices. List the components of early computing devices. Outline the uses of early computing devices Examples of Early Computing Devices a. Abacus d. Pascaline g. Difference engine b. Napier’s bone e. Jacquard’s loom h. Analytical engine c. Slide rule f. Leibniz multiplier i. Burroughs’s engine Features, Components and Uses of Early Computing Devices Abacus: Abacus is an instrument used in performing arithmetic calculations. It is probably the first calculating device. The Chinese invented it, and because of its success it spread from China to other countries. The abacus is also called a counting frame. It consists of a tablet or frame bearing parallel wires or grooves on which counters or beads are moved. A modern abacus consists of wooden frame with beads on parallel wires, and a crossbar oriented perpendicular to the wires that divides the beads into two groups. Each column or wire represents one place in the decimal system. The Abacus was used for addition and subtraction. It could not carry out complex mathematics operation. Slide Rule: Slide rule is a mechanical analog computer.It is also known as slipstick. It is used primarily for multiplication and divisions, and also for functions such as roots, logarithms, and trigonometry. It is not normally used for addition and subtraction. Slide rule come in a diverse range of style and generally appear in a linear or circular form with standardised set of markings(scales) essential to perform mechanical operations. The slide rule was developed by William Oughtred, an English mathematician. The slide rule looks much like a heavily caliberated ruler with a movable mid section.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 10 Napier’s Bone: Napier's bones are an abacus created by John Napier of Merchiston for calculation of products and quotients of numbers, in 1600. John Napier was a Scottish mathematician who invented logarithms and the decimal point. The device consists of a set of graduated rods based on the principle of logarithms. It was then used as a multiplication aid. To use Napier’s bones, the rods are moved up and down in a sliding manner against each other, matching the graduated rods. The device was a forerunner of the slide rule which emerged in the middle of 17 th century. Formerly used to perform multiplication and division but now taken over by modern electronic calculator. Pascal’s Calculator: Blaise Pascal a French Mathematician, Physicist and a religious philosopher, invented the Pascal’s calculator in 1642. Pascal’s calculator was first called the arithmetic machine, Pascal’s calculator and then the Pascaline. This machine was invented as a result of trying to help his father who was a tax collector and had the need for subtraction, addition, multiplication and division. Hence the need for this machine. Pascaline's mechanism was very promising but in practice was very complicated and the weighted ratchets tend to jam. Except that the ratchets didn't let the gears to rotate in both directions, so subtraction had to be implemented with nines complements trick, which is not so elegant way to perform a subtraction. In addition, as you can see from the previous examples, Pascaline is not a calculating machine, but actually just an adding machine. In fact, all similar machines with stylus setting mechanisms should be called adding machines rather than calculating machines. Despite all that Pascaline was a historical achievement and it is considered today as the first calculating device that the human race has discovered. Leibniz Multiplier: The Step Reckoner (or Stepped Reckoner) was a digital mechanical calculator invented by German mathematician Gottfried Wilhelm Leibniz around 1672 and completed in 1694.The name comes from the translation of the German term for its operating mechanism; staffelwalze meaning 'stepped drum'.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 11 It was the first calculator that could perform all four arithmetic operations: addition, subtraction, multiplication and division. Its intricate precision gear work, however, was somewhat beyond the fabrication technology of the time; mechanical problems, in addition to a design flaw in the carry mechanism, prevented the machines from working reliably. Jacquard Loom: The Jacquard loom is a mechanical loom, invented by Joseph Marie Jacquard, first demonstrated in 1801, that simplifies the process of manufacturing textiles with complex patterns such as brocade, damask and matelassé. The loom was controlled by a "chain of cards", a number of punched cards, laced together into a continuous sequence. Multiple rows of holes were punched on each card and each row of punched holes corresponded to one row of the design. Several such paper cards, generally white in color, can be seen in the images below. Chains, like the much later paper tape, allowed sequences of any length to be constructed, not limited by the size of a card. Difference Engine: The difference engine is an automatic mechanical calculator designed to tabulate polynomial functions. The name derives from the method of divided differences, a way to interpolate or tabulate functions by using a small set of polynomial coefficients. Both logarithmic and trigonometric functions, functions commonly used by both navigators and scientists, can be approximated by polynomials, so a difference 66 engine can compute many useful sets of numbers. The historical difficulty in producing error free tables by teams of mathematicians and human "computers" spurred Charles Babbage's desire to build a mechanism to automate the process.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 12 Analytical Engine: The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician Charles Babbage. It was first described in 1837 as the successor to Babbage's Difference engine, a design for a mechanical computer. The Analytical Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing- complete. Babbage was never able to complete construction of any of his machines due to conflicts with his chief engineer and inadequate funding. It was not until the 1940s that the first general-purpose computers were actually built. Charles Babbage: Charles Babbage, FRS (26 December 1791 – 18 October 1871) was an English polymath. He was a mathematician, philosopher, inventor and mechanical engineer, who is best, remembered now for originating the concept of a programmable computer. Considered a "father of the computer", Babbage is credited with inventing the first mechanical computer that eventually led to more complex designs. His varied work in other fields has led him to be described as "pre- eminent" among the many polymaths of his century. Hollerith Census Machine: Herman Hollerith (February 29, 1860 – November 17, 1929) was an American statistician and inventor who developed a mechanical tabulator based on punched cards to rapidly tabulate statistics from millions of pieces of data. He was the founder of the Tabulating Machine Company that later merged to become IBM. Hollerith is widely regarded as the father of modern automatic computation. Burrough’s Machine: Burroughs Adding Machine Company traced its founding to William Seward Burroughs who invented and patented the first workable adding and listing machine in St. Louis, Missouri in 1885. 1885: The first workable adding and listing machine is built and patented by William Seward Burroughs. 1886: The American Arithmometer Company is formed. 1886: The sales of the first adding and listing machine of the American Arithmometer Company began at a price of $475 each. 1898: William Seward Burroughs dies. 1900: Total sales for 1900 were 972 machines.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 13 Evaluation 1. Discuss about Burrough’s machine. 2. Identify what type of computer is the Slip stick? 3. Name three tools used for calculations from the time of abacus. 4. Explain why Charles “Babbage is referred to as the “Father of Computer”. 5. State three differences between Charles Babbage Difference and Analytical engine.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 14 HISTORICAL DEVELOPMENT OF COMPUTING DEVICE II (20TH CENTURY TO DATE) Objectives: List out features, components and uses of ENIAC. List out features, components and uses of EDVAC. State the features, components and uses of UNIVAC I. Description of personal computers. Brief Description The twentieth century computers are mechanical and electro-mechanical devices that possesses input unit, memory unit, processing etc. and can as well perform automatic operations. Among the early computing device, the twentieth century are Mark1, ENIAC, EDVAC, UNIVAC and Von Newman machine etc. Features, Components and Uses Of ENIAC ENIAC, in full Electronic Numerical Integrator and Computer, the first programmable general-purpose electronic digital computer, built during World War II by the United States. In the United States, government funding during the war went to a project led by John Mauchly, J. Presper Eckert, Jr., and their colleagues at the Moore School of Electrical Engineering at the University of Pennsylvania; their objective was an all- electronic computer. ENIAC was something less than the dream of a universal computer. Designed for the specific purpose of computing values for artillery range tables, it lacked some features that would have made it a more generally useful machine. It used plugboards for communicating instructions to the machine; this had the advantage that, once the instructions were thus “programmed,” the machine ran at electronic speed. Instructions read from a card reader or other slow mechanical device would not have been able to keep up with the all-electronic. The disadvantage was that it took days to rewire the machine for each new problem. This was such a liability that only with some generosity could it be called programmable. Nevertheless, ENIAC was the most powerful calculating device built to date. It was the first programmable general-purpose electronic digital computer. This gave ENIAC a lot of flexibility and meant that, while it was built for a specific purpose, it could be used for a wider range of problems.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 15 ENIAC ran continuously (in part to extend tube life), generating 150 kilowatts of heat, and could execute up to 5,000 additions per second, several orders of magnitude faster than its electromechanical predecessors. It and subsequent computers employing vacuum tubes are known as first-generation computers. (With 1,500 mechanical relays, ENIAC was still transitional to later, fully electronic computers.) Features, Components and Uses Of EDVAC EDVAC (Electronic Discrete Variable Automatic Computer) was one of the earliest electronic computers. Unlike its predecessor the ENIAC, it was binary rather than decimal, and was a stored program computer. The EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory capacity of 1,000 44-bit words (later set to 1,024 words, thus giving a memory, in modern terms, of 5.5 kilobytes). Physically, the computer comprised the following uses: a. A magnetic tape reader-recorder (Wilkes 1956:36 describes this as a wire recorder.) b. A control unit with an oscilloscope. c. A dispatcher unit to receive instructions from the control and memory and direct them to other units d. A computational unit to perform arithmetic operations on a pair of numbers at a time and send the result to memory after checking on a duplicate unit. e. A timer. f. A dual memory unit consisting of two sets of 64 mercury acoustic delay lines of eight words capacity on each line. g. Three temporary tanks each holding a single word. EDVAC's addition time was 864 microseconds (about 1.16 kHz) and its multiplication time was 2900 microseconds (about 0.38 kHz). The computer had almost 6,000 vacuum tubes and 12,000 diodes, and consumed 56 kW of power. It covered 490 ft² (45.5 m²) of floor space and weighed 17,300 lb (7,850 kg). The full complement of operating personnel was thirty people per eight-hour shift. Features, Components and Uses of UNIVAC I The UNIVAC I (Universal Variable Automatic Computer I) was the second commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work was started by their company, Eckert–Mauchly Computer Corporation, and was  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 16 completed after the company had been acquired by Remington Rand (which later became part of Sperry, now Unisys). In the years before successor models of the UNIVAC I appeared, the machine was simply known as "the UNIVAC". The UNIVAC I was the first American computer designed at the outset for business and administrative use (i.e., for the fast execution of large numbers of relatively simple arithmetic and data transport operations, as opposed to the complex numerical calculations required by scientific computers). As such the UNIVAC competed directly against punch-card machines (mainly made by IBM). Oddly enough the UNIVAC originally could not read or punch cards, hindering sales to companies concerned about the high cost of manually converting large quantities of data on cards. This was corrected by adding offline card processing equipment, the UNIVAC Card to Tape converter and the UNIVAC Tape to Card converter, to transfer data between cards and UNIVAC magnetic tapes. However, the early market share of the UNIVAC I was lower than the Remington Rand Company wished. To promote sales, the company joined with CBS to have UNIVAC I predict the result of the 1952 Presidential election. UNIVAC, I predicted Eisenhower would have a landslide victory over Adlai Stevenson who the pollsters favored. The result was a greater public awareness of computing technology. Personal Computers Desktop Computer A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile, laptop or portable computer. Early desktop computers are designed to lie flat on the desk, while modern towers stand upright. Most modern desktop computers have separate screens and keyboards. Prior to the widespread use of microprocessors, a computer that could fit on a desk was considered remarkably small. Early personal computers, like the IBM PC, were "desktop" machines, with a horizontally oriented computer case, usually intended to have the display screen placed on top to save space on the desktop. In modern usage the word "desktop" usually refers to tower cases that are in fact more often located on the floor under the desk than on a desk. Personal computers are also crucial component of Information Technology (IT) and play a key role in modern economies worldwide. The usefulness and capabilities of personal computers can be greatly enhanced by connection to the World Wide Web, as well as smaller networks that links to local computers or databases. It can also be used to access content stored on the Compact Disks (CDs), and to transfer files to personal media devices and video players. Personal computers are sometimes called microprocessors or micros. Powerful PCs designed for professional or technical use are known as work station.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 17 Laptop Computer A laptop is a portable personal computer with a clamshell form factor, suitable for mobile use. A laptop has most of the same components as a desktop computer, including a display, a keyboard, a pointing device such as a touchpad (also known as a trackpad) and/or a pointing stick, and speakers into a single unit. Portable computers, originally monochrome CRT-based and developed into the modern laptops, were originally considered to be a small niche market, mostly for specialized field applications such as the military, accountants and sales representatives. As portable computers became smaller, lighter, cheaper, and more powerful and as screens became larger and of better quality, laptops became very widely used for a variety of purposes. Palmtop Computers Palmtop is a computer that has asmall screen and compressed keyboard and is small enough to be heldin the hand, often used as a personal organizer. A Handheld PC or H/PC for short, is a computer built around a form factor which is smaller than any standard laptop computer. It is sometimes referred to as a Palmtop. The first handheld device compatible with desktop IBM personal computers of the time was the Atari Portfolio of 1989. Some Handheld PCs use Microsoft's Windows CE operating system, with the term also covering Windows CE devices released by the broader commercial market. Evaluation 1. Briefly describe the twentieth century computers. 2. Highlight the limitations of the ENIAC. 3. Discuss EDVAC and state two reasons why it is different from ENIAC. 4. Enumerate three components of EDVAC. 5. Define a personal computer and list three types.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 18 INPUT DEVICES Objectives: Discuss the meaning of input devices. List out examples of input devices. Description of each example of input device. Meaning of Input Devices An input device is any computer hardware equipment used to send data into the main storage of the computer for processing. It is the part of the computer or any device that is used to invoke a command or instructions into the computer to obey in order to accomplish its task. Examples of Input Devices a. Keyboard e. Joystick b. Mouse f. Card readers c. Scanner g. Light pen d. Microphone h. Digital camera. Description of Each Example of Input Device Keyboard A keyboard is an input device which is used to input data into the computer system. It remains the most vital interface device between the user and the computer. It is the most common input device for entering data into the computer. It is also an electronic device with several groups of keys electronically linked to the processor when attached to the computer. There are two main types of keyboards: a. Standard Keyboard b. Enhanced Keyboard Structure / layout and Function: The keyboard is structure in such a way that makes typing easy and easily accessible by the fingers. It has different sets of Keys for performing various functions in controlling the computer. In General, there are three types of arrangement of letters on the keyboard, namely:  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 19 a. Qwerty b. Azerty c. Dvorak d. Colemark. The standard layout of letters, numbers, and punctuation is known as a QWERTY keyboard because the first six keys on the top row of letters spell QWERTY. The QWERTY keyboard was designed in the 1800s for mechanical typewriters and was actually designed to slow typists down to avoid jamming the keys. The AZERTY keyboard is the French version of the standard QWERTY keyboard. AZERTY keyboards differ slightly from the QWERTY keyboard. Another keyboard design, which has letters positioned for speed typing, is the DVORAK keyboard. Unlike the traditional QWERTY keyboard, the Dvorak keyboard is designed so that the middle row of keys includes the most common letters. Keys on the Keyboard Keyboard is basically divided into seven a. Function Keys b. Numerical Keypad c. Alphabetic keys d. Special Character Keys e. Alphanumeric keys g. Cursor Control keys g. Command Keys Function Keys: This contains button labeled F1 to F12 that can be used as special command which can perform some operations that are included in the operating system or application. A program is capable of not only using each of the function keys, but also combining the function keys with the ALT or CTRL key, for example, Microsoft Windows users can press ALT + F4 to close the program currently active. This is a special section of the keyboard that contains numbers and functions to enter data in the form of numbers and arithmetic operations. Numeric keypads usually operate in two modes: when Num Lock is off, keys 8, 6, 2, 4 act like arrow keys and 7, 9, 3, 1 act like Home, PgUp, PgDn and End; when Num Lock is on, digits keys produce corresponding digits. Numeric keypads are useful for entering long sequences of numbers quickly, for example in spreadsheets, financial /accounting programs, and calculators. Input in this style is similar to that of a calculator or adding machine.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 20 Alphabetic Keys: This is a section of the keyboard that contains the alphabets A to Z for typing text. These keys can be used in conjunction with some other control keys to perform certain functions in window applications. Special Character Keys: Special character keys are those keys that cannot be found on the keyboard. They are inserted by pressing a combination of keys on the keyboard, or using the character map. They may be letters, fonts, or symbols. To access the character map in Windows, click through the ff links: “Windows Button > All Programs > Accessories > System Tools > Character Map” Alphanumeric Keys: These keys include the same letter, number, punctuation, and symbol keys on a traditional typewriter. A-Z and 0-9. The alphabetic characters become uppercase when the shift key or Caps Lock key is depressed. The numeric characters become symbols or punctuation marks when the shift key is depressed. Cursor Control Keys: These keys provide control over the cursor and display on the computer screen Command Keys: These are keys on the keyboard that perform certain actions in windows once they are pressed. They are Escape, Enter, Delete, Backspace, Print Screen/SysRq, Scroll Lock, Pause/Break, Insert and Delete. Mouse: This is a small device moved with the hand to control the movement of the pointer on a computer screen. It is an input device which can be used by clicking and dragging. It is also a common pointing device used with a computer system with GUI (Graphic User Interface). It enables the computer user to select or activate items on screen by placing pointer arrow on items and performing required action. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. Mouse is used for drawing as well as pointing images. Types of Mouse  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 21 a. Mechanical: Has a rubber or metal ball on its underside that can roll in all directions. Mechanical sensors within the mouse detect the direction the ball is rolling and move the screen pointer accordingly. b. Optical: It uses a laser to detect the mouse's movement. You must move the mouse along a special mat with a grid so that the optical mechanism has a frame of reference. Optical mice have no mechanical moving parts. They respond more quickly and precisely than mechanical and optomechanical mice, but they are also more expensive. Other types of mouse a. Serial mouse b. Ps/2 mouse c. Wireless mouse Features of the Mouse a. Button: The mouse typically has two buttons – a primary button (usually the left button) and a secondary button (usually the right button). b. Wheel: It is located in between the two buttons. It is used to scroll up and down, zoom in and zoom out in some application. c. Motion Technique: They are used in controlling cursor movement on the screen. There are three types; Mechanical technique, optomechanical and optical. d. Battery Life: If you go wireless, you're going to be replacing those batteries from time to time. To extend the battery life of your mouse, look for one that comes with an on/off switch and use it. Function of the Mouse a. Pointing b. Clicking c. Dragging d. Double – clicking Operations of the Mouse To use the mouse, you need just two fingers; your right thumb and third finger. Your fist finger should be on the left button while the third finger should also rest on the right button, ready to click. Scanner It is an input device which uses light-sensing equipment to convert images such as pictures or text into electronic signals that can be manipulated by a computer. It can be used to store, change and send image or text into the system unit. Joystick: Joystick are used mainly for playing computer games. It is a pointing device composed of a lever that moves in multiple directions to navigate a cursor or other graphical objects on a computer screen. A button on the top of the joystick sends command to the computer.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 22 Card Readers Card readers as 66the name implies, can read data from a memory card. It is highly used in exchanging data among different digita6l products such as camera, MP3, MP4, mobile phones and computer. Light Pen It is a stylus with a light-sensitive tip that is used to draw directly on a computer’s video screen, or to select information on the screen by pressing a clip in the light pen or by pressing the light pen against the surface of the screen. Digital Cameras These are digital devices that capture pictures and video, and send them into the computer through a connected specialized cable such as USB (Universal Serial Bus). A good example of this is the common webcam which are used for recording videos and for taking pictures that are shared live on the internet. Evaluation 1. List and explain the keys on the keyboard. 2. Explain the structure of a keyboard. 3. Mention three functions of the mouse. 4. Explain the features of the mouse. 5. State the function of a digital camera  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 23 OUTPUT DEVICES Objectives: Discuss the meaning of output devices. List out examples of output devices. Description of each example of output device. Meaning of Output Devices This is a device that releases the processed data from the computer to either the user or any of the storage devices. Or they are peripherals of the computer that transfer information from the computer to the user. There are many devices that produce data in different form such as audio, visual and hard copy. Examples of Output Devices a. Monitor b. Printer c. Plotter d. Speaker e. Oscilloscope. Description of Each Example of Output Device Monitor: This is an output device that resembles the television screen. Modern computer monitors can display a wide variety of information, including text, icons (pictures representing commands), photograph, graphics, video and animation. It is the most commonly used output device. The monitor is a soft copy (means we can modify contents of data and data is temporarily on the screen) output device. CRT MONITOR LCD MONITOR Structure of the Monitor The main features of the monitor are the screen, the cable and the monitor screen size. The portion of the monitor that displays information is called the screen. Like a television screen, a computer screen can show still or moving pictures. The monitor is a soft copy (means we can modify contents of data and data is temporarily on the screen) output device. The monitor also has a connecting cable tethered to the system unit. This cable is called VGA (Visual Graphic Array) cable.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 24 Types of Monitors a. Monochrome monitors b. Color monitors c. Composite monitors Monochrome Monitor: These monitors display images only in single color. This color can be white, green, blue, red or amber. This monitor can display shades of one color and the computer industry uses the term gray scales to refer to the number of shades of a color that can be shown on a monochrome monitor’s screen. Color Monitor: This monitor shows graphics with full colors. These monitors produce images in three mixed colors, which are red, green and blue that is why these are also called RGB monitors. A typical monitor can display 256 to 65536 colors. The composite color screen is similar to a color television set, but it can handle data more quickly and has a sharper picture (better resolution) and more colors. Each monitor must be paired with an appropriate video display adapter card. (i.e., EGA – Enhanced Video Adapter, VGA – Video Graphic Adapter, CGA – Color Graphic Adapter, SVGA – Super Video Graphic Adapter). Technology Used for Most Monitors a. CRT (Cathode ray tube) b. LCD (Liquid crystalline display) c. LED (Light emitting diode) d. OLED (Organic light emitting diode). Uses of Monitor a. It is used to see data as they are inputted. b. It is used to display output c. It is used to display error messages on the screen. d. It is used to display graphic / text. Printers: Printers are the most commonly used output devices that can be found in almost all computer centers. Printers are used to get prints of important documents on a paper. The output, which is generated by a printer, is called hard copy of the data. Printer is also called a hard copy output device.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 25 Types of Printers There are various types of printers, depending on the technology they use in printing on paper or other material medium. They can be categorized into two namely: Impact Printers and Non-Impact printers Impact Printers: This type of printing devices creates an image by using some mechanism to physically press an inked ribbon against the paper, thereby causing the ink to be deposited on the page in the shape desired. They tend to be noisy when they are in use. Examples are: a. Dot-Matrix Printer: These types of printers form each character as a group of small dots, using group of wire located in the printing element. They are also known as dot character printers. b. Line Printers: They print line by line. The disadvantages of line printers are that they cannot print graphics, the print quality is low, and they are very noisy. c. Character Printers: Character printers print one character at a time and hence they are slow printers. d. Daisy-Wheel Printers Non-Impact Printers They are the type of printers that do not operate by striking a head against a ribbon. They work by applying ink on paper. They are the most commonly used types today. Examples are: a. Inkjet Printers: They create a digital image by propelling droplets of ink onto paper. b. Laser Printers: They are electro-photographic printers that use a cylindrical drum that rolls electrically charged ink onto paper. c. Thermal Printers: A thermal printer produces a printed image by selectively heating coated thermal paper when the paper passes over the thermal head. Projector A projector is an output device used to show presentations.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 26 Differences between impact printer and non-impact printer The most commonly used printers today at home, small offices and large-scale businesses are the inkjet and laser printers. The following table presents the differences between impact printer and non-impact printer. S/N Impact printers Non-impact printer 1. Its speed is slower Its speed is faster. 2. Its printing quality is lower Its printing quality is higher. 3. It normally uses continuous paper It normally uses individual paper sheet. 4. It generates noise during printing It does not generate noise during printing. 5 It uses inked ribbon for printing It uses toner or cartridge for printing 6 It is less expensive It is more expensive. Speaker: A computer peripheral that converts computer digital sound files into audible sound. File format used to save sound file determines quality of audio file. They can be built into the system unit or connected with cables. Plotter: A specialized printer designed to print onto very large pieces of paper. Pen plotters print by moving a pen or other instrument across the surface of a piece of paper. The bill boards, like the ones we see by the road side, are printed using plotters. A plotter. Evaluation 1. Define and mention the features of Output Devices. 2. Identify five {5} examples of Output Devices. 3. List the types and uses of Monitors. 4. Differentiate between Inkjet and Laser Printers. 5. Define Impact and Non-Impact Printer.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 27 DATA AND INFORMATION Objectives: Discuss the meaning of data and information. List out the examples of data and information. Outline the differences between data and information. State and explain the sources of data and information Meaning of Data and Information Data: This can be defined as basic facts about a place someone or something. Data are raw facts. Data are unprocessed facts. Data can also mean facts, events, activities and transactions that have been recorded. Examples of data are names, scores, words, figures etc. Data can also be referred to as raw facts that have not been processed. As a result, such data is not meaningful yet, since it has not yet been processed by the computer system. Data is the plural of datum. Information: This can be defined as data that have been converted into a more meaningful and useful form unlike data. Information is the end-product of a processed data. Information may however be used as an input data for further processing. Therefore, Data and Information are often used interchangeably. Information is organized and meaningful unlike data. Examples of information are Processed examination score arranged according to grade levels or positions in class. Examples of Data and Information Examples of data are; Height, name, sex, age of students, numbers etc., while The example of information is examination scores arranged according to grade, level or position. Differences Between Data and Information S/N Data Information 1. They are unprocessed facts They are processed. 2. They are not meaningful They are Related and meaningful. 3. They serve as computer input They serve as computer output. 4. They are unorganized They are organized. Sources of data and information Data and information can be sourced from a variety of places, depending on the type of data and the context in which it's being used. Here are some common sources:  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 28 Primary Sources a. Surveys and Questionnaires: Data collected directly from respondents through structured questions. b. Experiments: Data generated through controlled experiments. c. Observations: Data gathered by observing subjects in natural settings. d. Interviews: Information collected through direct conversations with individuals. Secondary Sources a. Government Reports and Publications: Census data, economic reports, public health statistics, etc. b. Academic Journals: Peer-reviewed articles and studies from various fields. c. Books: Scholarly books, textbooks, and other published works. d. News Media: Newspapers, magazines, and online news sources. e. Industry Reports: Market research reports, white papers, and other industry-specific publications. Online Data Sources a. Databases and Repositories: Data from sources like PubMed, JSTOR, and Google Scholar. b. Statistical Agencies: Websites of organizations like the World Bank, WHO, and national statistical agencies. c. Open Data Portals: Government and organizational portals that provide free access to various datasets (e.g., data.gov, EU Open Data Portal). d. Social Media and Web Analytics: Data from platforms like Twitter, Facebook, and Google Analytics. Evaluation 1. Define Data and Information. 2. List five examples of Data and Information. 3. Differentiate between Data and Information. 4. Outline and explain any three sources of data and information  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 29 BASIC COMPUTER OPERATION Objectives: Define booting. List and explain types of booting. Describe the booting process. List and explain the components/features of windows desktop. Definition of Booting Booting: This is the process of starting up a computer from a powered-off state to a fully operational state where the operating system is loaded and ready for use. It involves a series of steps that initialize the hardware components, load the operating system, and prepare the system for user interaction. Booting can be initiated by powering on the computer or performing a restart (reboot). Types of Booting There are two main types of booting: a. Cold Boot (Hard Boot): This is the process of starting a computer that is completely powered off. It involves turning on the power to the system, which triggers the boot sequence from the very beginning. b. Warm Boot (Soft Boot): This is the process of restarting a computer that is already powered on. It usually involves the operating system initiating a reboot sequence without completely cutting the power to the system. The booting process includes several key stages, such as the Power-On Self-Test (POST), loading the bootloader, initializing the operating system kernel, and starting system services and the user interface. Description of Booting Process The booting process is the sequence of steps that a computer system goes through from the time it is powered on until it is ready for use. Here is a detailed description of the typical booting process: a. Power-On Self-Test (POST): When the computer is powered on, the CPU initializes and starts the BIOS (Basic Input/output System) or UEFI (Unified Extensible Firmware Interface) firmware. b. The BIOS/UEFI performs a Power-On Self-Test (POST) to check the hardware components such as the RAM, disk drives, and other peripherals to ensure they are functioning correctly. c. Bootstrap Loader: After the POST is successful, the BIOS/UEFI looks for the bootloader, typically located in the Master Boot Record (MBR) of the primary storage device (like the hard drive or SSD). The bootloader is a small program responsible for loading the operating system into memory. d. Loading the Bootloader: The BIOS/UEFI reads the bootloader code from the MBR and transfers control to it. Common bootloaders include GRUB (for Linux) and BOOTMGR (for Windows).  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 30 e. Loading the Operating System: The bootloader locates the kernel of the operating system and loads it into memory. The kernel is the core part of the operating system that manages system resources and hardware. f. Kernel Initialization: The kernel initializes and configures the system hardware, sets up memory management, and starts essential services. It also mounts the root filesystem, which contains the rest of the operating system files. g. Starting System Services: Once the kernel is fully operational, it starts system services and background processes (daemons in Unix-like systems or services in Windows). These services handle various functions like networking, system logging, and device management. h. User Login: Finally, the system starts the graphical user interface (GUI) or command-line interface (CLI) login prompt. The user can then log in and start using the computer. This process ensures that the computer hardware is functioning correctly and that the operating system is loaded and ready for use. The exact steps and components may vary slightly depending on the specific hardware and operating system being used. Differences between cold booting and warm booting S/N Cold booting Warm booting 1. Cold booting is also known as hard booting, Warm booting is also known as soft booting. slow start, and cold start 2. Cold booting is a safe type of booting Warm booting is dangerous. The consequences of warm booting can be disastrous for the machine and the data, particularly if it has not been preserved. 3. The computer's power button starts the Warm booting is started by the operating system. cold booting. 4. The technique of restarting a system from a Warm booting is the technique of restarting an power-off state and returning it to normal already-on system without completely turning it off. function is known as cold booting. 5. The POST test is run upon cold booting to The POST test is skipped during warm booting. verify the different computer components Components/Features of Windows Desktop A Windows desktop has various components and features designed to help users interact with the operating system and manage their applications and files. Here are the primary components and features: Desktop Components a. Desktop Background: The wallpaper or image that serves as the background of the desktop screen. b. Icons: Shortcuts to applications, files, folders, and system functions. Common icons include: i. This PC: This access to drives and system files. ii. Recycle Bin: This store deleted files and folders until they are permanently removed. iii. Network: This access to network and internet connections.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 31 Taskbar a. Start Menu: This access to installed applications, system settings, and power options (shutdown, restart). b. Search Bar: This quickly search for files, applications, and system settings. c. Task View Button: This allows switching between open applications and virtual desktops. d. Pinned Applications: This quick access to frequently used applications. e. System Tray (Notification Area): This displays system notifications, background processes, and access to system settings like volume, network, and battery status. f. Clock and Date: This displays the current time and date. Window Elements a. Title Bar: This displays the name of the application or document and provides window control buttons (minimize, maximize/restore, close). b. Menu Bar: This contains menus for application functions (File, Edit, View, etc.). c. Toolbars: Quick access to commonly used functions and tools within an application. d. Status Bar: This displays information about the current status of the application or document. e. Scroll Bars: This allows scrolling through content that extends beyond the visible window area. System Features a. File Explorer: This is the tool for browsing and managing files and folders on the computer. b. Control Panel / Settings App: This provides access to system settings and configurations. c. Task Manager: This monitor and manages running applications and processes. d. Action Center: This provides quick access to system notifications and quick actions (Wi-Fi, Bluetooth, etc.). e. Cortana: This is the virtual assistant for voice commands and queries (availability depends on the Windows version). Accessibility Features a. Ease of Access Center: Provides accessibility options like magnifier, narrator, and on-screen keyboard. b. High Contrast Mode: Enhances visibility for users with visual impairments. c. Keyboard Shortcuts: Provides quick access to various functions using keyboard combinations. Additional Features a. Virtual Desktops: This allows the creation of multiple desktops to organize and manage open applications. b. Snap Assist: This helps to easily resize and arrange open windows on the screen. c. Windows Search: Integrated search functionality to find files, applications, and web results.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 32 d. Windows Defender / Security: This built-in antivirus and security features to protect the system from threats. These components and features provide a comprehensive and user-friendly interface for interacting with the Windows operating system, making it easier to manage tasks, access applications, and customize the desktop environment. Steps Process of Shutting down a Computer System. a. Press the Start button. b. When the start menu opens, select shut down. c. Click OK when the shutdown box displays. d. Turn the Monitor Off. e. Turn the main power button OFF. Evaluation 1. Define booting. 2. State and explain the two types of booting. 3. List out any four features of windows desktop. 4. State five differences between cold and warm booting. 5. List the steps process of shutting down a computer system.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 33 COMPUTER ETHICS / HUMAN ISSUES Objectives: Describe the meaning of computer security. List and explain the classification of computer threats. Enumerate the reasons for computer security. Outline the steps on how to secure computer room and systems. Discuss the indebt analysis of computer virus. Meaning of Computer Security Computer Security is the protection of computer system from damage or theft. The security of computer is necessary to forestall unwanted or unwarranted access to the hardware components, software or electronic data, as well as to avoid misdirection of services computer has to offer. Classification of Computer Threats a. Back Door: A backdoor in a computer system is any secret method of by-passing normal authentication or security control b. Denial of Service Attack (DoS): This is when all the necessary services are (e.g., network service or software service) are unavailable to intended users. c. Direct –Access Attacks: This is when an unauthorized user is gaining physical access to a computer to copy data from it. d. Eaves Dropping: This is the act of listening to a private conversation without authorized permission. This is usually possible by planting and installing a suspicious program into the system on a network that help monitor conversation (e.g., carnivore and Narus Int, commonly used by the FBI and NSA) e. Phishing: This is an attempt to use instant messaging to acquire sensitive information such as user names, passwords and credit card details directly from users. f. Social Engineering: This aims to convince a user to disclose secrets by impersonating, for example, banks, a contractor or a customer. Reasons for Computer Security a. To protect the computer system from virus attack b. To protect the computer from theft c. To protect the system from natural disaster or physical damage d. To protect the information in the system from corruption How to Secure Computer Room and Systems a. Computer room must be well ventilated b. Always close the door of the computer room  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 34 c. Cover the system after usage to prevent dust d. Use an Anti-virus to protect the computer from virus attack e. Install burglary-proof to all the windows and doors of the computer rooms. f. Use a lock such as cover lock to protect USB drives and disk locks g. Use password to protect files and documents. In-depth Analysis of Computer Virus In 1949, Hungarian American Mathematician, John Von Neumann in Princeton New Jersey, proposed that; theoretically computer program should be able to replicate itself. This theory was tested in 1950 at Bell laboratory when a game called Core-Wars was developed. The term Virus was first used for such replicating program in 1983 by American Electrical Engineer, Fred Cohen. He described virus as a self-replicating computer program. In 1985, the first Trojan Horse appeared as game called NUKE-LA. Brain virus appeared in 1986 and spread worldwide in 1987. The first Bootstrap virus called Stone and internet warm appeared in 1988. By definition: Computer Virus is a self-replicating piece of computer program that can partially or fully attach itself to computer files or applications and cause havoc to the computer system or irritations to computer users. Types of Computer Virus a. File or Parasitic Virus This virus infects executable files or program in the computer. The executable files are file with.exe extension. The virus attached itself to the executable files of the host program in such a way that it is ran first. b. Bootstrap Virus These viruses reside on the first portion of the hard disk or floppy disk known as boot sector. These viruses replace either the programs that store information about the disk contents or the program that starts the computer. These viruses spread by the means of exchange of disks. c. Multipartite Virus These viruses have the ability of file and bootstrap viruses; and are to infect either files or boot sectors. These spread if a computer user boots from an infected memory unit (e.g., flash drive) or access infected files. d. Macro Virus These viruses are written in macro-languages and automatically execute when legitimate program written in macro language is being executed. Note, macro language are programs that allow computer users to create new features and utilities. e. Script Virus These are written in script languages like VB scripts, Java script etc., and are executed each time legitimate script program is to be executed. This virus is more powerful than the macro because script programs are  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 35 very close to operating system environment. A good example is the “I Love You” virus created in 2000 and infected an estimated 1 in 5 personal computers. f. Polymorphic Virus This type of virus changes codes when it passes to another machine. It is always very difficult for anti- virus to detect this kind of virus and it is not a common virus because of its complexity in coding. g. Stealth Virus This usually hides its presence in the infected file by making it look not infected. However, it is very easy for any antivirus to detect such virus. Computer Virus Prevention Tips a. Create backup of legitimate /original program or software b. Obtaining software from the legitimate source c. Quarantine your computer i.e., remove your system from the network connection d. Regularly install operating system patches (update your system) e. Installation of recent and well-designed Anti-virus. Sources of Virus a. Infected external Storage media b. Neighborhood system via Network connection c. Internet In-depth Analysis of Computer Anti-virus Antivirus is the program specially designed to stop the effect of virus on the computer system. Basic Functions of Antivirus a. Scanning for virus b. Quarantine virus c. Eradicate virus Types of virus scan a. On-demand scanning: On-demand scanning refers to the process of manually initiating a scan of a computer system, specific files, or directories for malware, viruses, and other security threats. This is usually done using antivirus software or other security tools. b. On-access scanning: On-access scanning, also known as real-time scanning or background scanning, refers to the continuous monitoring of files and system activities by antivirus software to detect and prevent malware infections. This type of scanning occurs automatically whenever a file is accessed, opened, modified, or saved, providing immediate protection against potential threats.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 36 Examples of antivirus a. Dr. Solomon tool kit f. Sophos k. Komodo b. Smadav g. F-secure l. Kasperky etc. c. AVG h. Avira d. C.A Antivirus i. Eset e. Norton j. E-scan General Effects of Virus a. It slows down the computer response time. b. It brings unfamiliar or meaningless text into the main text. c. It clogs system network or prevent the system from getting connected to the internet. d. It makes saving into the memory units difficult. e. It delays / prevents computer booting process. f. It disrupts the functionality of installed programs. Evaluation 1. Mention any three types of computer threats and how such threats can be corrected. 2. State any three types of computer virus and their effect on the computer system 3. Define anti-virus and state any five examples.  ST. FINBARR’S COLLEGE, AKOKA CITADEL OF EXCELLENCE 37 REFERENCES Richard W. B. et al (1986): “Using Computer in New Generation Age”, First edition, Library of Congress Cataloging in Publication Data, USA. Otuka J.O.E et al (2013): “New Computer Studies for Senior Secondary Schools 1”, Learn Africa Plc Publication. Akukwe A.C. et al (2013): “Evans Computer Science for Senior Secondary Schools Book1”, Evans Brothers (Nigeria Publishers) Limited E- Library: Encounter Encyclopedia, An online resource.