Section 1 - I.T

Basic Computer Components and the IPOS Cycle

• Definition of a Computer: An electronic device operating under the control of instructions stored in its memory. It is a fundamental aspect of information technology.

• The IPOS Cycle: Represents the four basic tasks of any computer (Fig 1.1):   - Input: Accept data from the outside world.   - Processing: Manipulate data into information.   - Output: Produce results from processing for the user in various forms.   - Storage: Store data or information for a short or long time for future use.

• Devices Categorized as Computers: Desktop machines, laptops, handheld games consoles, and portable devices such as smartphones and tablets.

• General Categories: The components of a computer are divided into hardware and software.

Categories of Computer Hardware

• Hardware Definition: The physical parts of a computer.

• The Central Processing Unit (CPU): Known as the brain of the computer; it controls how the rest of the computer works.   - Control Unit (CU): Carries out software instructions and directs the flow of data through the computer.   - Arithmetic and Logic Unit (ALU): Performs all calculations and logic operations.

• Input Devices: Components used to get data into a computer, such as a mouse, keyboard, and scanner.

• Output Devices: Components used to get processed information out, such as a printer, computer screen, or speakers.

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

• Storage Media vs. Storage Devices:   - Storage Media: The physical materials where data is kept, including hard disks, $CD-ROMs$, $DVDs$, and $USB$ flash memory sticks.   - Storage Devices: The hardware that reads from or writes to the media, such as hard disk drives, $CD-ROM$ drives, and $DVD$ drives. Many allows saving (writing) as well as reading.

• Peripheral Devices: Hardware located outside the $CPU$ but controlled by it. These can be added to the system and include input, output, and storage devices.

Software Classification

• Software Definition: Computer programs that tell the hardware how to work. Without software, hardware would perform no tasks.

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

• System Software (Operating System): Software that controls the hardware and the operation of all other software.   - Microsoft Windows: Written by Microsoft Corporation; the most commonly used operating system.   - Utility Software: Specialized software aimed at protecting and maintaining the system software (acting like a car mechanic for a generic engine). Functions include:     - Protecting against computer viruses.     - Backing up (making copies of) files.     - File recovery after software has stopped working (a 'crash').

• Application Software: Software that instructs a computer to perform a specific task. Examples include word processors, spreadsheets, and databases.

Information and Communication Technology Definitions

• Information Technology (IT): Describes the equipment (hardware and software) that allows humans to access, retrieve, convert, store, organize, manipulate, and present data and information. It can also refer to the act of using such equipment to produce information.

• Communications Technology (CT): Describes telecommunications equipment through which data and information can be accessed. Examples include phones, faxes, scanners, modems, and computers.

Manual Input Devices

• Definition: Devices where a user must manually enter or transfer data into the computer.

• Keyboard and Keypad:   - Features alphabet keys, digit keys, and function keys.   - Operation: Pressing a key sends a numeric code to the computer representing that key.   - Disadvantage: Common mistakes (transcription errors) by pressing incorrect keys.   - Specialized Versions: Found on children's toys (e.g., picture of a farmyard that makes animal noises) or programmable robots in schools.   - Keypad: A block of buttons with digits, symbols, or letters, often found as a sub-section on standard keyboards.

• Mouse:   - A pointing device that moves a screen pointer relative to motion on a flat surface.   - Button Functions: Left button is for 'selecting' items; right button is for 'accessing' menus.   - Mechanical Mouse: Uses a rubber ball underneath for rolling.   - Optical Mouse: Uses light to track movement.   - Cordless Mouse: Communicates via infrared or radio waves rather than a physical connection.

• Document Scanner: Transfers pictures, graphics, and text to a computer by scanning images line-by-line from top to bottom. Results can be emailed, printed, or used in other programs.

• Microphone: Inputs audio data. Supports voice-activated or voice-response systems, converting spoken words into text or carrying out spoken commands.

• Digitisers:   - Digital Camera: Captures still and video images in electronic format for later editing or printing.   - Webcam: A digital camera connected to a computer for internet transmission, streaming, traffic monitoring, or surveillance.   - Touchpad: A flat rectangular surface that senses finger movement; commonly replaces the mouse on laptops and notebooks.   - Graphics Tablet: A flat, touch-sensitive surface used with a special pen called a stylus to capture drawings and handwritten signatures.

• Pointing Devices:   - Light Pen: A device for screen interaction, largely replaced by touchscreens.   - Stylus: A pen-like device with a plastic or felt tip used to exert pressure on graphics tablets or touchscreens to avoid finger oil on screens.

• Remote-Control Devices: Send data through signals (often infrared) when buttons are pressed. Used for television channels, electronic gates, and slide presentations.

Direct Data Entry (DDE) Devices

• Definition: Devices that transfer information automatically from a document into a computer without manual keying. Used for large volumes of data.

• Barcode Reader:   - Barcode: A group of vertical bars of varying widths representing country of origin, manufacturer, and item code. Note: Price is NOT included in the barcode itself.   - Tools: Laser wands, fixed scanners, or camera-based readers.   - Features: Cheap to produce (normal ink/printer), durable (readable even if creased or wrinkled), and facilitates Electronic Point of Sale ($EPOS$) systems for fast billing and automatic re-ordering.

• Smart Card and Magnetic Strip Readers:   - Magnetic Strip: Found on credit/debit cards. Information is read by 'swiping'. Susceptible to corruption if scratched or soiled.   - Electronic Funds Transfer at Point of Sale (EFTPOS): The system of transferring account data and costs into the banking system via card swipe.   - Smart Card: More sophisticated than magnetic cards; contains a built-in electronic circuit and gold-colored contacts. Can store significantly more data and does not require remote database access for every transaction.

• Optical Mark Recognition (OMR):   - Relies on reading precisely positioned marks (lines) on a grid.   - Applications: Lottery slips and standard examination multiple-choice answer sheets.   - Performance: Extremely fast and accurate; requires no human intervention for final information production.

• Optical Character Recognition (OCR):   - Scans handwritten or printed text and converts it into an editable file for word processors.   - Constraint: Accuracy varies and can be poor if the source document is low quality.   - Turnaround Document: A document with unique computer-printed info that requires human-added marks (often utilizing $OCR$ and $OMR$ together) before being fed back into the computer.

• Magnetic Ink Character Recognition (MICR):   - Used by banks for processing cheques. Details (cheque number, account number, branch code) are printed in magnetic ink.   - Features: Reads a specific font very quickly with $100\%$ accuracy. Highly secure (cannot be overwritten by pen) and remains readable even if the cheque is folded.   - Disadvantage: Both the magnetic ink and the reader are expensive.

• Sensors and MIDI:   - Musical Instrument Digital Interface (MIDI): Allows music data input through piano-type keyboards or strike-responsive pads.   - Physical Sensors: Respond to signals such as temperature, wind speed, direction, sunshine hours, and humidity for weather forecasting (Meteorological Office). Also used in automatic doors and burglar alarms.

Output Devices and Copies

• Soft Copy: Non-permanent output. Examples include monitor displays, audio from speakers, electrical signals, and data sent between computers.

• Hard Copy: Permanent output on physical media, such as printed reports and pictures.

• Display Devices:   - Monitor: Separately plugged into a system unit or integrated (laptops/mobile).   - Interactive Whiteboards (Smartboards): Large touch-sensitive plastic boards for teaching/presentations; respond to projectors, tablets, or magnetic pens.   - Screen Technology: $LCD$ (Liquid Crystal Display) and $LED$ (Light-Emitting Diode).   - Bitmap (bmp): A computer image created by mapping the location and color of data bits. It consists of thousands of pixels.   - Pixel: Short for 'picture element'.

• Features of a Computer Screen:   - Size: Diagonal dimension. Common sizes are $14\,inches$ to $19\,inches$.   - Resolution: Clarity determined by dots per inch. Higher pixel density equals higher detail.   - Colour: Ranges from $16$ to $16.7\,million$ colors. More colors lead to smoother photo-quality graphics.   - Cursor/Pointer: Symbol (like 'I' for text or an arrow for mouse) showing the work location.   - Scrolling: Moving text/graphics up, down, or sideways to bring them into view.

Printing and Plotting Devices

• Impact Printers: Strike through an inked ribbon like a typewriter. They are noisy and produce poor graphics but are excellent for multiple copies using carbon paper (e.g., payroll).   - Dot-matrix printer: Uses pins to print a pattern of dots. Mostly obsolete except for carbon copy tasks.

• Non-impact Printers: Use ink spray or toner powder fixed by heat. They are quiet and inexpensive to manufacture.   - Inkjet Printers: Low-priced, good quality (up to $4$ to $6\,pages\,per\,minute$). Use cartridges that require frequent replacement. Ideal for home use (greeting cards, school work).   - Laser Printers: High-speed ($8$ to $12\,pages\,per\,minute$) and high-resolution ($300$ to $1200\,dpi$). Use toner cartridges and are cheaper to run than inkjets for large workplaces.   - Thermal Printers: Use heat on chemically treated paper. Used for $ABM$ receipts, credit card slips, and ultrasound images. Print eventually fades if exposed to light/heat.   - 3D Printers: Create models layer-by-layer from melted plastic based on digital designs.

• Plotters: Used by architects, car designers, and engineers for accurate charts and 3D drawings. They use pens or toner.   - Flatbed Plotter: Paper is still while pens move.   - Drum Plotter: Paper rolls over a cylinder; can produce very large drawings.   - Pinch-roller Plotter: A hybrid of flatbed and drum styles.

• Audio Output Devices:   - Loudspeakers: Distribute sound to a group.   - Headphones: For individual listening to avoid disturbing others.   - Earphones/Earbuds: Small headphones fitting inside the ear.   - Headset: Headphones with an attached microphone.

Primary Memory

• Main Memory: Located on the main circuit board for rapid communication with the $CPU$. Data is stored at specific addresses.

• Word: The largest amount of data that can be moved together for processing.

• Random-access Memory (RAM):   - Function: Holds temporary instructions, programs, and data for the $CPU$.   - Feature: Data is accessed almost immediately.   - Disadvantage: Volatile (data is lost when power is off).   - Standard size: $2$ to $8\,GB$.

• Read-only Memory (ROM):   - Function: Contains basic input/output instructions ($BIOS$) put there during manufacture.   - Feature: Non-volatile and cannot be changed.

• Hybrid Memory: Combines features of both $RAM$ and $ROM$. Can be read/written like $RAM$ but maintains contents without power like $ROM$. Examples include flash memory used for storing code.

Data Representation and Units

• Transistors (Bistable Devices): Microelectronic switches that represent 'on' and 'off' states.

• Bits (Binary Digits): Zeros ($0$) and ones ($1$). The smallest unit of data a computer works with.

• Processor Complexity: Modern chips like Intel i5 or i7 contain over $27\,million$ transistors on a silicon slice.

• Units of Storage:   - Byte: $8\,bits$.   - 1\,Kilobyte\,(KB): $2^{10} = 1024\,bytes$.   - 1\,Megabyte\,(MB): $2^{20} = 1024\,kilobytes$.   - 1\,Gigabyte\,(GB): $2^{30} = 1024\,megabytes$.   - 1\,Terabyte\,(TB): $2^{40} = 1024\,gigabytes$.

Secondary Storage

• Definition: Media and methods used to save programs and data permanently (non-volatile).

• Magnetic Media:   - Magnetic Tape: Plastic strip coated with ferrous oxide. Sequential access (retrieving the 50th item requires passing the first 49). Vital for large-scale network backups, often performed at night.   - Hard Disks: Rigid magnetic disks inside a drive. Main secondary storage for computers ($700\,GB$ to $1\,TB$ capacities).

• Optical Disks: Use lasers to read/store data. Susceptible to damage from light, heat, or dust.   - CD-ROM: Read-only, capacity is $650\,MB$.   - CD-R: Recordable (Write Once Read Many - $WORM$).   - CD-RW: Rewritable; can be erased.   - DVD (Digital Versatile Disk): Capacity $4.7\,GB$ to $17\,GB$. Used for films and games.   - Blu-ray (BD): Capacity $25\,GB$ to $100\,GB$. Used for high-definition films.

• Flash Memory:   - USB Flash Drives: Non-volatile, portable, faster than optical disks. Sizes $8$ to $256\,GB$.   - Memory Cards (SIM, SDHC): Used in phones, cameras, and consoles. Capacity ranges from $2\,GB$ to $1\,TB$.

• Cloud-based Storage: Data stored on multiple remote computers via the internet (e.g., Dropbox, Google Drive).   - Advantages: Immediate access anywhere, data redundancy (if one server fails, another has the data).   - Risks: Security concerns, unauthorized access, or data corruption.

System Software and The Operating System (OS)

• OS Examples: Windows 10, Mac OS X, Linux (Desktop); iOS, Android (Mobile).

• Tasks of the OS:   - Booting: Starting the computer. The $BIOS$ on $ROM$ checks hardware, then loads the $OS$ from disk to $RAM$.   - Hardware Control: Manages peripherals, memory allocation, and $CPU$ time.   - Software Control: Regulates how applications and games run.   - Memory Management: Uses 'virtual memory' (swapping blocks between $RAM$ and storage) to run programs too large for physical memory.   - Input/Output Management: Coordinates communication via drivers.   - Process Management: Allocates $CPU$ time to various tasks.   - File Management: Saving, renaming, and organizing files.

Data Processing Modes

• Batch Processing: Data is collected in a group and processed all at once on a schedule (e.g., electricity bills, payroll). Advantage: No human interaction needed during processing.

• Time-sharing: Multiple users sharing one computer simultaneously. The $CPU$ provides small 'time slices' to each user.

• Real-time Processing: Data processed without significant delay; always up-to-date (e.g., aeroplane landing controls, ticket reservations).

• Multi-tasking: Running more than one program at once on one $CPU$.

• Multi-processing: Using two or more processors to execute programs simultaneously.

• Multi-programming: Executing multiple programs on a single processor simultaneously.

• Online vs. Offline: A device is 'online' when connected to the main processor and turned on.

Data Transfer and Compression

• Upload: Transferring data from a local computer to a network/internet server.

• Download: Receiving data from a network/internet server to a local computer.

• File Transfer Protocol (FTP): Used for downloading software updates.

• File Compression: Reducing file size for storage or transmission (e.g., WinZip, Winrar).   - Graphics: $JPEG$, $PNG$.   - Music: $MP3$.   - Video: $MPEG$ ($MP4$).

Application Software Types

• General-purpose Software: Non-specific software used by a wide audience (e.g., Word, Excel). It is cheaper and usually 'bug' free.

• Customised Software: General-purpose software modified with specific programming modules for a user.

• Custom-written (Bespoke) Software: Taylor-made for specific organizations (e.g., military, hospitals). It is expensive and takes a long time to write.

• Specialised Software: Written for one specific task only (e.g., camera software on a phone, online card games).

• Integrated Software: A package containing major application types (word processor, spreadsheet, database) closely related to each other (e.g., Microsoft Office, Adobe Creative Suite).

User Interfaces (HCI)

• Human-Computer Interface (HCI): Controls the interaction between human and machine.

• Requirements: Should be attractive, simple, quick, and consistent.

• Hardware Interfaces: Touchscreens, sensors, games controllers (buttons/grips).

• Software Interfaces:   - Command-line Interface (CLI): Requires typing specific language commands (e.g., Windows PowerShell). Difficult for beginners.   - Menu-driven Interface: Users choose options from a list. Can be visual or verbal (automated phone systems).   - Graphical User Interface (GUI): Often called $WIMP$ (Windows, Icons, Menus, Pointers). Easiest for beginners but requires more memory.     - Windows: Resizable screen areas for documents.     - Icons: Tiny pictures representing programs or folders.     - Menus: Pull-down (activated by left-click) or Pop-up (activated by right-click).     - Pointers: Controlled by pointing devices to select items.

Types of Computer Systems

• Mainframe: Very large capacity, multiple $CPUs$, supports thousands of users. Used by banks and airlines (e.g., IBM zEnterprise). Extremely expensive.

• Desktop Systems: Personal computers for single users. Common specs: $8\,GB\,RAM$, $1\,TB$ hard disk, $3\,GHz$ processors.

• Embedded System: A dedicated system designed for specific functions within a larger device. Reliable and low power (e.g., washing machines, traffic lights, watch).

• Mobile Devices: Handheld, battery-powered devices (laptops, tablets, smartphones).

Common Hardware Problem Troubleshooting

• Power Issues:   - Ensure cables are plugged in and outlets are live.   - Bypass surge suppressors to test for faults.   - Test power cables on other compatible devices.

• Printer Issues:   - Check for paper jams under cartridges.   - Verify printer driver installation and $Wi-Fi$ connectivity.   - Ensure the correct printer is selected in the 'Print' dialogue.   - For poor quality: Check ink alignment or replace empty cartridges.

• Monitor Issues:   - Check if in 'power save' mode (blink light); move mouse to wake.   - Keep away from strong magnetic sources (amplifiers) or electrical interference (fans, fluorescent lamps).   - Shield from bright lights/windows to reduce glare.

• Battery Issues:   - If the device shuts off immediately after unplugging the adapter, the battery or cord likely needs replacement.

Questions & Discussion

• Q1: List the four basic tasks of any computer.   - A: Input, processing, output, and storage.

• Q2: State the name of the cycle that represents the four basic tasks.   - A: The IPOS cycle.

• Q3: What is the general name given to the physical parts of a computer?   - A: Hardware.

• Q4: Explain the terms CPU, CU, and ALU.   - A: CPU (Central Processing Unit) is the brain; CU (Control Unit) directs data flow; ALU (Arithmetic and Logic Unit) handles math and logic.

• Q5: Difference between input and output devices?   - A: Input gets data into the computer; output gets processed information out.

• Q6: Another name for system software?   - A: Operating system.

• Q7: Name for programs that tell hardware how to work vs. equipment for accessing data?   - A: (a) Software; (b) Communications Technology (CT).

• Q8: Name for a system using body parts to identify someone?   - A: Biometric system.

• Q9: Name for a document with unique computer info needing human additions?   - A: Turnaround document.

• Q10: Terms for pixels, and printers for multiple carbon copies?   - A: Pixels are the tiny dots on screens; dot-matrix printers handle carbon copies.

• Q11: Smallest chunk of data a computer works with?   - A: A bit.

• Q12: Main use of magnetic tape?   - A: Backing up large amounts of data for organizations/networks.

• Q13: Name for the process of starting a computer?   - A: Booting.

• Q14: Describe Bespoke software.   - A: Software written for use in specific organizations like hospitals or banks.

• Q15: What does WIMP stand for?   - A: Windows, Icons, Menus, Pointers.