Information Technology - CSEC - notes

Oxford excellence for the Caribbean - Information Technology (Third Edition)

Preface

  • This textbook incorporates recent changes to the Caribbean Examination Council's (CSEC) Information Technology (IT) syllabus.

  • It aims to support the interest of Caribbean students in using ICT tools for productivity and problem-solving.

  • The textbook provides support material to explore every section of the IT syllabus through topic discussion, worked examples, and a wide range of questions.

  • Chapters are aligned with syllabus sections, with detailed treatment of computer fundamentals and information processing in Chapters 1 and 2.

  • Updated Chapter 6 covers web page design for theory examination and the practical requirement for the School Based Assessment (SBA).

  • Chapters 9 and 10 address problem-solving and program implementation, allowing teachers to choose a programming language.

  • Chapter 11 introduces Pascal programming fundamentals, and Chapter 12 introduces Visual Basic for Applications for Microsoft applications.

  • Each chapter includes end-of-section questions for reinforcement and end-of-chapter questions testing learning from other chapters.

  • The appendix includes guidance for the SBA, whether candidates are working individually or in groups.

CSEC IT Structure

  • Paper 1: 1 1/4 hours, 60 compulsory multiple-choice questions, 30% of final mark.

  • Paper 2: 2 hours, four compulsory questions from all areas of the syllabus, 45% of final mark.

  • Paper 3-1: School Based Assessment (SBA), one practical assignment comprising word processing, web page design, spreadsheets, database management, problem solving, and programming, 25% of final mark.

  • Paper 3-2: Alternative to SBA for private candidates, a theory and practical paper testing skills required for the SBA, 25% of final mark.

Syllabus Section

  • 35 questions - Theory

  • 15 questions - Productivity tools

  • 10 questions - Problem solving

  • 35 marks - Theory

  • 30 marks - Productivity tools

  • 25 marks - Problem solving and programming

Contents

1 Fundamentals of hardware and software

1.1 Basic computer components

  • A computer is an electronic device operating under the control of instructions stored in its memory.

  • It can accept data (input), manipulate data (processing), produce results (output), and store data and results for future use (storage).

  • These four basic tasks represent the IPOS cycle.

  • The term 'computer' includes desktop machines, laptops, handheld games consoles, smartphones, and tablets.

  • Basic computer components are categorized as hardware or software.

Hardware

  • Hardware refers to the physical parts of a computer.

    • Central Processing Unit (CPU): The brain of the computer, including the Control Unit (CU) and the Arithmetic and Logic Unit (ALU).

    • CU carries out instructions and directs data flow.

    • ALU performs calculations and logic operations.

    • Input Devices: Devices that get data into a computer (e.g., mouse, keyboard, scanner).

    • Output Devices: Devices that get processed information out of a computer (e.g., printer, computer screen, speakers).

    • Memory: Enables a computer to temporarily store instructions and data.

    • Storage Media: Includes hard disks, CD-ROMs, DVDs, and USB flash memory sticks.

    • Storage Devices: Includes hard disk drives, CD-ROM drives, and DVD drives.

  • Peripheral devices are located outside the CPU but are controlled by it (e.g., input, output, and storage devices).

Software

  • Software refers to computer programs that tell the hardware how to work.

Computer Programs

  • Instructions produced by programmers to create system and application software.

System Software

  • Controls the hardware and how all other software works; also called an operating system (e.g., Windows).

    • Includes utility software, which protects and maintains the system software (e.g., protecting against viruses, backing up files, recovering files after crashes).

Application Software

  • Instructs a computer to carry out a specific task (e.g., word processors, spreadsheets, databases).

Information and communication technology

  • Information Technology (IT) is the equipment (hardware and software) that allows us to access, retrieve, convert, store, organize, manipulate, and present data and information.

  • Communications Technology (CT) is the telecommunications equipment through which data and information can be accessed (e.g., phones, faxes, scanners, modems, computers).

1.2 Input devices and media

  • 'Input' means to enter data, programs, commands, and user responses into the memory of a computer.

  • An input device is any device that transfers data from the outside world into a computer.

  • Two general categories of input devices: manual input devices and direct data entry (DDE) devices.

Manual Input devices

  • Requires the user to manually enter or transfer data into the computer.

Keyboard and Keypad

  • Keyboard: Has alphabet keys, digit keys, and function keys for entering letters, words, or numbers.

    • Disadvantage: easy to make mistakes by pressing the wrong keys.

  • Keypad: A block of buttons that contain digits, symbols, or alphabetical letters.

Mouse

  • A pointing input device; moving it along a flat surface moves the pointer on the screen.

    • Left button: used to 'select' items.

    • Right button: used to 'access' menus.

    • Mechanical mouse: Has a rubber ball underneath to help it roll smoothly.

    • Optical mouse: Uses light to track its movements.

    • Cordless mouse: Uses infrared or radio waves to communicate with the computer.

Document Scanner

  • Transfers pictures, graphics, and text to computer by scanning the image from top to bottom and transferring it to the computer.

Microphone

  • Enters data through sound; computer responds by carrying out instructions or turning spoken words into text (voice-activated or voice-response systems).

Digitiser

  • Converts drawings and images into data.

    • Digital camera: Captures still and video images and stores them in electronic format.

    • Webcam: A type of digital camera connected to a computer for transmission of still or moving images over the Internet.

Touch-Sensitive Devices

  • Touchscreen: A screen that is sensitive to touch, eliminating the need for a keyboard or mouse.

  • Touchpad: A flat rectangular surface that senses the movement of one or more fingers on its surface; found on laptops and notebooks. Functions as a mouse.

Graphics Tablet

  • A flat, touch-sensitive drawing surface that uses a special pen called a stylus to capture drawings and handwritten signatures.

Pointing Devices

  • Light Pen: Similar to a mouse, but rarely used.

  • Stylus: A small pen-like device with a plastic or felt tip that uses pressure instead of ink; used to draw on graphics tablets or type on touchscreens.

Remote-Control Devices

  • Send data through signals each time a button is pressed; used to change television channels, open electronic gates, and manage slide presentations.

Biometric Systems

  • Use a person's body to uniquely identify them.

    • Fingerprints, face, iris recognition, size and shape of the hand.

Direct Data Entry (DDE) Devices

  • Transfer information automatically from a document (e.g., form or barcode) into the computer, without manual entry.

Barcode Reader

  • Reads barcodes (groups of vertical bars of different widths) found on products.

    • Groups of bars represent different numbers, which represent the product's country of origin, manufacturer, and item code.

    • Electronic Point of Sale (EPOS) systems use barcode data to produce customers' bills, track inventory, and re-order goods automatically.

Smart card

  • A card with a built-in electronic circuit and gold-colored contacts, allowing data to be read from or written onto the card.

Optical Mark Recognition (OMR)

  • Relies on precisely positioned marks on a form being read by a special scanner.

Optical Character Recognition (OCR)

  • Scans handwritten or printed text and turns it into a file that can be edited, reformatted, and reprinted.

  • OMR and OCR are often used together in a turnaround document.

Magnetic Ink Character Recognition (MICR)

  • Reads cheque number, account number, and branch code printed on cheques using magnetic ink.

Sensors

  • Respond to a wide variety of signals; used to collect data automatically into a system.

1.3 Output devices

  • 'Output' means to show, print, or store the results of processed data.

    • Soft copy: Non-permanent (e.g., computer monitor, audio from speakers, electrical signals).

    • Hard copy: Permanent; printed for review away from the computer (e.g., printed reports and pictures).

Display Devices

  • Computers usually display output on a screen or monitor.

  • Types of display devices: LCD (liquid crystal display) flatscreens and LED (light-emitting diode) screens.

  • Features of a computer screen include its size and resolution.

Features of a Computer Screen

  • Size: dimension of the screen (e.g., 14 inches to 19 inches measured diagonally).

  • Resolution: Determines how clear and detailed the output on the screen can be. More pixels per inch result in clearer, more detailed graphics.

  • Colour: Number of colors displayed can vary from 16 to 16.7 million. The more colors, the smoother the graphics appear.

  • Cursor/pointer: A Symbol that shows where you are working on the screen. It may appear as I for text and for the mouse pointer location.

  • Scrolling: Allows the text or graphic to be moved up or down or brought into view on the screen.

Printing Devices

  • Output a hard copy of your work. Two main categories: impact and non-impact.

Impact Printers

  • Strike through a carbon or inked ribbon (e.g., dot-matrix printer).

Non-Impact Printers

  • Do not involve striking the paper; use ink spray or toner powder (e.g., inkjet printers, laser printers, thermal printers).

    • Inkjet printers- good quality but slower. use cartridges

    • Laser printers - faster and high quality use toner.

    • Thermal printers - use heat on chemically treated paper.

3D Printers

  • Create a 3D model layer by layer, from the bottom upward, using melted plastic.

Plotters

  • Use colored pens or toner to draw an image on paper; used by car designers, architects, and engineers for accurate charts, diagrams, and 3D drawings.

Audio Devices

  • Include a sound card for recording (input) and playback (output) of sound.

1.4 Primary memory

  • Main memory is located directly on the computer's main circuit board. Data stored at a specific memory location can have its address contents accessed to be read from, written to or processed.

  • The largest amount of data which can be moved together to be processed is called a word.

Types of Memory

  • Random-Access Memory (RAM): Holds temporary operating instructions, programs, and data. Volatile–data is lost when the computer is turned off.

  • Read-Only Memory (ROM): Contains basic input/output instructions that can be read but not changed (non-volatile).

  • Hybrid Memory: Combines features of both RAM and ROM (e.g., flash memory).

How Data is Represented

  • Everything the computer does results from transistors or bistable devices. Transistors that are 'off' and 'on' states are used to represent the zeros (0) and ones (1) that make up the binary number system.

  • These zeros and ones are known as bits (binary digits).

1.5 Secondary storage

  • Refers to the media and methods used to keep programs, data, and information available for later use. Saves programs and data permanently.

Devices and Media

  • Storage media keep data, instructions, and information on the physical hardware of a computer for future use (e.g., hard disks, compact disks, and tapes).

  • Storage devices record and retrieve data, instructions, and information to and from storage media (e.g., hard disk drives, compact disk drives, and tape drives).

  • Secondary storage can be grouped into local storage and cloud-based storage

Local Storage

  • Involves users having storage devices or media with data in their possession or generally knowing of their location.

Magnetic Media

  • The cheapest way to store and back up data.

    • Magnetic Tape: Narrow strip of plastic coated with ferrous oxide; used primarily as a back-up storage medium.

    • Hard Disks: Store a large amount of data; most are inside computers.

Optical Disks

  • Store much more data than most magnetic media.

    • CD-ROM (Compact Disk Read-Only Memory): Accesses up to 650 MB of stored data; read-only media.

    • CD-R (Compact Disk Recordable) and CD-RW (Compact Disk Rewritable): Allow data to be written to disks; data on CD-RWs can also be erased.

    • DVDs (Digital Versatile Disks): Used for storing any kind of digital data; can store much more data than CD-ROMs.

    • Blu-ray Disks (BD): Designed to replace DVDs by storing several hours of video using a storage capacity of up to 100 GB.

Flash memory

  • USB (Universal Serial Bus) flash memory drives: convenient alternatives to hard drives; used for storage and data backup, but mostly used for transfer of computer files

  • Flash memory cards: inserted into digital cameras, video games consoles, laptop computers, MP4s, mobile phones and other music players.

Cloud-Based Storage

  • Involves storage of data by users on multiple computers anywhere in the world.

1.6 System software

  • Controls hardware and how all other software works (e.g., operating systems and utility software).

Operating System

  • The most commonly used system software (e.g., Microsoft Windows, Apple's Mac OS X, LINUX).

Booting

  • The process of starting a computer.

Hardware Control

  • The operating system supports tasks like accepting input and transferring data between primary and secondary memory or displaying output.

Software control

  • The operating system controls how all software applications, games or other programs work on the computer.

Memory Management

  • When a program or data is too large to fit into main memory, a method called virtual memory can be used to split the program into manageable blocks.

Input/output management

  • Since each device has a program called a driver that allows the device to communicate with the computer, the flow of information among devices must be managed and coordinated.

Process management

  • Process management allocates time for processes to use the CPU, checks on processes waiting to use the CPU, and signals when the CPU is available.

File management

  • Files need to be saved, copied, renamed and deleted. A file manager checks the amount of memory needed to perform these tasks and manages the organisation of the files in secondary storage.

Utility Software

  • Specialised software that tries to protect and maintain the system software (e.g., protecting software against damage caused by computer viruses, backing up files, and recovering files after software has stopped working (crashed)).

1.7 Data processing

  • Data can be processed by the most suitable means and transferred to one or more computer systems for further processing, output, or storage.

  • Batch Processing: Data is collected together in a batch before processing starts. Suitable for tasks where a large amount of data is processed regularly (e.g., utility bills, payroll systems, examination report card systems).

  • Time-Sharing: Allows many users to share time on a single computer. Each user is given a slice of CPU time (e.g., a bank's bankcard system).

On-line and Real-time Processing

  • Computers are on-line when they are connected to a main processor and turned on.

Data Transfer

  • Most computer users will, at some time or another, need to transfer files between computers.

    • Uploading data involves transferring data from your computer to another computer on the network or the Internet

    • Downloading involves receiving data to your computer from another computer on the network or the Internet

1.8 Application software

  • Any program that enables the computer to carry out one or more specific tasks.

General-Purpose Software

  • Applications that are not specific to any organization or business and can be used by anybody (e.g., word processing, databases, spreadsheets, presentations, drawing and painting).

Customised and Custom-Written Software

  • Customised software is general-purpose software that has been modified to perform specific tasks for the user.

  • Custom-written software is software written for use in specific organizations (e.g., military, hospitals, banks).

Specialised Software

  • Software is written solely for a specific task rather than a range of functions. (e.g., the software on your mobile phone for your camera).

Integrated Software

  • A Program that includes all the major types of application (e.g., word processing, spreadsheet and database) and brings them together into a single software package (e.g., Microsoft Office and Adobe Creative Suite).

1.9 User interfaces

  • A user interface involves various ways of capturing or transferring data between a user and the computer system

Hardware Interfaces

  • input devices such as touchscreens, sensors, digital cameras and special keyboards

Software interfaces

  • Available after the computer has booted up and the operating system has been loaded, allowing the user to interact with the computer or device through an interface.

Types of Software Interfaces

  • Command-Line Interfaces: Require the user to type in commands using a special language.

  • Menu-Driven Interfaces: Use menus (lists of options) as an easy alternative to learning program commands.

  • Graphical User Interfaces (GUI): Use windows, icons, menus, and pointers (WIMP) for ease of use.

1.10 Types of computer systems

  • A Computer communication system usually transports data through the network from one point to another.

Types of computer systems

  • Mainframe - very large capacity with several CPUs, capable of supporting hundreds or even thousands of users simultaneously.

  • Desktop systems - A personal computer that fits on an office desk

  • Mobile devices - (also called handheld devices) include laptops, notebooks, netbooks, tablets, smartphones, e-readers and games consoles

  • Embedded system - designed for one or two specific functions

1.11 Common computer hardware problems

Troubleshooting basic computer problems

  • Computer, laptop or mobile device does not respond when power is turned on

  • Printer problems

  • Monitor problems

  • Battery problems

2 Information processing

2.1 Data and information

  • Data is raw, unprocessed facts.

  • Information is processed data.

  • Data processing is the manipulation of data to obtain information.

  • An information system is any record-keeping system.

  • The value of information can include the cost of production, the cost of distribution and the value to the purchaser.

Information as a commodity

  • An information commodity is an item of information that can be bought or sold.

2.2 Validation and verification

  • A common problem with manually entering data into a computer system is that it is very easy to input incorrect data.

Data entry errors

  • When an operator enters data using a keyboard and mixes up digits and/or letters. Such a situation of error is called transposition errors.

Validation

  • Data validation is the computerised checking of input data for errors before it is processed.

Validation Checks

  • Range check - Check for values within specified range limits.

  • Reasonableness check - Check if the data makes sense and obeys specified criteria.

  • Data type check - Check for required format being alphabetic or alphanumeric.

  • Consistency check - Compares contents of fields to make sure they make sense.

  • Presence check - Check that required data has been entered .

  • Format check - Validates required data formats

  • Length check - Validates required data entry length.

  • Check digit - Used to detect errors arising from transcription and also to ensure that codes originally produced by a computer are re-entered into another computer correctly.

Verification

  • Checking for mistakes such as transcription errors when data is copied from one medium or device to another. Does not guarantee the entered data is correct but confirms it matches the source.

    • Double (data) entry - Data is entered twice using a program that checks each second entry against the first.

    • Visual checks

Interpretation of coded data

  • Before the responses to questionnaires can be analysed, they must be edited and coded before the data entry process.

Problems associated with shared data

  • Problems of data accuracy when the data records are saved.

  • Computer systems that provide shared access to data must have security features in place.

2.3 Automated methods of data capture

  • Many of the output devices discussed in Chapter 1 are human-readable, meaning that a hard copy of the output is printed as reports, graphs, charts and so on.

Data-capture forms

  • Responses from the forms are called human-readable since data entry personnel manually enter the responses written on the forms.

Alternatives to turnaround documents

  • In some industries, turnaround documents are being replaced by small handheld computers, including mobile devices.

2.4 File organisation and access

  • File organisation and access relates to the use of records, fields and files.

Definitions

  • A field contains a single data item.

  • A record is a collection of related data fields (possibly of different data types).

  • A data file is a collection of records holding the same type of information but about different objects or individuals.

Master and transaction files

  • A master file is a permanent file which is kept up-to-date.

  • A transaction file is a temporary file which is used to update the master file after a certain time(at the end of each day or week, for example).

Record matching

  • A primary key is normally used to identify the record you want to update or delete.

Serial and sequential file organisation

  • Serial file organisation is the simplest type of file organisation. The records are arranged one after another, in the order in which they were added.

  • A sequential file is one in which the records are stored in sorted order on one or more key fields.

Direct access file organisation

  • A direct access file, also called a random access file, allows access to a particular record in the file using a key.

Index sequential file organisation

  • An indexed file is used to speed up the key search in a file.

2.5 Information processing

  • The processing of data into information can be done in almost all sectors of business.

Health care

  • maintain patient records in hospitals and clinics

  • monitor patients' vital signs in hospital, and at home

  • perform computer-assisted medical tests

Banking

  • Computers are used to keep track of all bank transactions.

Payroll

  • Uses an information processing system to calculate the wages of each employee, print out pay-slips and record the information for accounting purposes.

Library

  • Most university libraries provide online access for their staff and students via an e-information portal

Control systems

  • Integrated into a control system which has sensors to input information, a processing unit (computer) which decides how to respond to the inputs, and output devices which do what is required.

Industry

  • A whole manufacturing process is controlled automatically by a computer system.

Weather forecasting

  • Automatic data recording for weather forecasting is a more accurate alternative to manual data collection.

    • Computer data can be collected continuously whereas humans may get tired, and it can also be collected in situations not safe for humans.

    • It is extremely fast. Computers can easily take thousands of measurements in a second.

Supermarket stock control

  • Shops need to hold stocks of goods they sell, and