Computer Applications and System Software, Study notes of Technology

Download Computer Applications and System Software and more Study notes Technology in PDF only on Docsity!

IGCSE INFORMATION & COMMUNICATION

TECHNOLOGY

THEORY NOTES

Types and Components of Computer Systems

Hardware &Software

Hardware

• Hardware refers to the physical components of a computer system
• These components can be internal or external Internal Components
• Central Processing Unit (CPU) : the computer's "brain" that performs calculations, processes instructions, and controls other components
• Processor : a chip inside the CPU that carries out instructions from a program
• Motherboard : the main circuit board that connects all internal components Internal Memory
• Random Access Memory (RAM) : temporary storage for running programs and data; it is volatile, meaning data is lost when the computer is turned off
• Read-Only Memory (ROM) : permanent storage for essential data, like the computer's BIOS; it is non-volatile, meaning data is retained even when the computer is turned off Hardware Components
• Graphics card : processes images and videos for display on a monitor
• Sound card : processes audio for output through speakers or headphones
• Network Interface Card (NIC) : enables connection to a network, such as the internet
• Camera : captures images or video for input into the computer
• Internal/external storage devices : stores data permanently, such as hard drives or USB flash drives
• Input devices : allow users to enter data, like keyboards and mice
• Output devices : display or produce results, like monitors and printers

Software

• Software refers to programs that control the operation of a computer or the processing of electronic data Application Software
• Application software provides the services that users require to solve a task
• E.g.: o Word processing : creating and editing text documents

• GUI is more resource-intensive than CLI
• Dialogue-based and gesture-based interfaces enable more natural and intuitive interaction Advantages & Disadvantages Type of Operating System Advantages Disadvantages Command Line Interface
• Faster for experienced users
• Consumes fewer system resources
• Difficult for beginners to learn
• Less visually appealing Graphical User Interface
• User-friendly and easier to learn
• Visually appealing
• Better help facilities
• Can exchange data between different applications
• Slower for some tasks compared to CLI
• Consumes more system resources (RAM / HDD)
• Slower to run as graphics have to be loaded
• Restrictive as can only use pre-defined functions Dialogue-based & Gesture-based Interfaces
• Natural and intuitive interaction
• Accessible for users with disabilities
• May require additional hardware
• Limited functionality compared to CLI and GUI Analogue & Digital Data
• Analogue data is continuous and varies smoothly over time
• Digital data is discrete and represented in binary form (0s and 1s) Differences between Analogue & Digital Data
• Analogue data can have any value within a range, while digital data has a limited set of values
• Digital data is less prone to noise and distortion compared to analogue data
• Digital data can be easily manipulated, stored, and transmitted by computers Converting Analogue to Digital Data

• Analogue data must be converted to digital data so it can be processed by a computer
• This process is called analogue-to-digital conversion (ADC) and is performed by an analogue-to-digital converter Converting Digital to Analogue Data
• Digital data must be converted to analogue data so it can be used to control devices
• This process is called digital-to-analogue conversion (DAC) and is performed by a digital-to-analogue converter Main Components of a Computer Systems

Central Processing Unit (CPU)

• The Central Processing Unit (CPU) is the computer's "brain" responsible for processing instructions entered into the computer
• The CPU processes instructions and performs calculations in order to produce an output CPU Functions
• Fetches instructions from memory
• Decodes the instructions to determine the required operation
• Executes the operation
• Stores the result back in memory or sends it to an output device CPU Components
• The CPU is made up of 3 main components: o Arithmetic Logic Unit (ALU) o Control Unit (CU) o Registers

Memory

Memory is used to store data and instructions temporarily for the computer to process Characteristics of ROM and RAM

Keyboard & Numeric Keypad Entering text and numbers Fast and accurate input for experienced users The steeper learning curve, repetitive strain injury Pointing Devices Navigate and interact with computer interfaces Intuitive and precise control Requires flat surface, the strain on the wrist Remote Control Control devices from a distance, e.g., TVs and media players Convenient, no direct physical contact is needed Limited range, may require line-of-sight Joystick/Driving Wheel Simulation and driving games Enhances gameplay experience, realistic control Expensive, limited use outside of gaming, bulky Touch Screen Direct interaction with the screen using fingers or a stylus Intuitive, no need for a separate pointing device The screen may get dirty, less precise than a mouse Scanners and Cameras Capture images and convert them into digital format Accurate reproduction, easy to share and store Quality depends on resolution, which can be expensive Microphone Capture a sound for recording or communication purposes Hands-free input can be used for voice recognition May pick up background noise, the quality varies Sensors and Light Pen Sensors detect changes in the environment; light pen interacts with screens Can automate tasks, provides real-time information May require calibration, affected by the environment

Direct Data Entry (DDE) Devices

Direct Data Entry Device Use Advantages Disadvantages Magnetic Stripe Reader Reading information stored on magnetic stripes, e.g., credit cards, ID cards Fast, simple to use, reliable Data can be easily erased, and limited storage capacity Chip and PIN Reader Processing debit and credit card transactions in stores Secure, quick transaction, reduced fraud risk Requires PIN input, potential for skimming RFID Reader Reading information from RFID tags, e.g., inventory tracking, access control No line-of-sight is needed, multiple tags are read simultaneously The expensive system, and potential privacy concerns

OMR (Optical Mark Recognition) Reading marked areas on forms, e.g., multiple-choice exams Fast processing, reduced human error Limited to specific forms, cannot read handwriting OCR (Optical Character Recognition) Converting printed text into digital text, e.g., digitising books The fast and accurate, searchable digital text Can struggle with complex layouts, font dependent Barcode Reader Scanning barcodes to retrieve product information and prices Fast and accurate, low cost Requires line-of-sight, limited data storage QR Scanner Scanning QR codes for information retrieval or linking to websites Can store more data, versatile uses Requires a smartphone or specific scanner, quality dependent

Output Devices and Their uses

Characteristics of Output Devices

• Output devices : display or produce the results of data processing from a computer system e.g.: o Monitor o Printer o Speakers o Projector Differences between Input & Output Devices
• Input devices send data or instructions to the computer, while output devices receive data from the computer
• Input devices are used for user interaction and data entry, while output devices display or produce the results of data processing Output Device Use Advantages Disadvantages Monitor Displaying computer-generated visual information on a screen Real-time display, adjustable settings Power consumption, potential glare Touch Screen (Output) Displaying visual information and allowing user interaction with the screen Intuitive, space-saving Susceptible to smudges, potential calibration issues

o USB flash drives o optical discs (CDs, DVDs)

• Backing storage is typically slower than internal memory but has a larger capacity
• It is non-volatile, meaning it retains data when the computer is powered off Differences between Backing Storage & Internal Memory Backing Storage Internal Memory Function Long-term storage of files, programs, and data Temporary storage of data and essential instructions while the computer is running Examples HDD, SSD, USB flash drives, optical discs (CDs, DVDs)

RAM, ROM

Access Speed Slower Faster Capacity Larger Smaller Volatility Non-volatile (retains data when powered off) RAM: volatile, ROM: non-volatile Storage Media Storage Media Examples Use Advantages Disadvantages Magnetic Drives Hard disks, Magnetic tape Long-term data storage, backup, and archiving High capacity, low cost per GB Slower access time, moving parts, susceptible to magnets Optical Discs CD, DVD, Blu- ray Data storage, audio, video, and software distribution Portable, durable, low cost Limited capacity, susceptible to scratches

Solid- State Media Memory cards (SD, xD, CFast), USB Drives, Solid State Drives Fast data storage for portable devices and modern computers Fast access time, no moving parts More expensive, limited write cycles Storage Devices Storage Devices Use Media Advantages Disadvantages Magnetic Drive Long-term data storage, backup, and archiving Magnetic High capacity (10TB), low cost per GB Slower access time, moving parts, susceptible to magnets Fixed Magnetic Hard Drive General-purpose storage in computers and servers Magnetic Hard Disk Large storage capacity (5TB), relatively fast Moving parts, vulnerable to physical damage Portable Magnetic Hard Drive External storage for data transfer and backup Magnetic Hard Disk Portable (5TB), large storage capacity Slower than SSDs, vulnerable to physical damage Magnetic Tape Drives Backup and archiving, especially for large volumes of data Magnetic Tape High storage capacity (10TB), low cost Slow access time, sequential access CD Audio and data storage, software distribution

CD

Affordable, widely compatible Low capacity (700MB), susceptible to scratches DVD Higher capacity storage for data, video, and software distribution

DVD

Higher capacity than CD (8.5GB), affordable Susceptible to scratches, lower capacity than Blu-ray Blu-ray High-definition video and high capacity data storage Blu-ray High capacity (50GB), high- resolution video storage More expensive, and requires specific hardware Fixed Solid- State Drive (SSD) Fast internal storage for modern computers Solid- State Fast access time, no moving parts, high capacity (30TB) More expensive, limited write cycles

• Laptop Computers: o Portable with integrated display, keyboard, and touchpad o Battery powered o Less powerful and less expandable than desktops
• Smartphones: o Portable and lightweight o Touchscreen interface o Multifunctional (phone, internet access, camera) o Anti-glare screen o Front and rear facing camera o Battery powered o Uses Bluetooth, WiFi, 3G, 4G, 5G o Has an on screen keyboard
• Tablet Computers: o Larger touchscreen than smartphones o Ideal for media consumption and web browsing o Limited expandability o Anti-glare screen o Front and rear facing camera o Battery powered o Portable and lightweight o Uses Bluetooth, WiFi, 3G, 4G, 5G o Has an on screen keyboard
• Phablet Computers: o Combine features of smartphones and tablets o Larger screen than smartphones o Can be used for phone calls Uses of Mobile Computers
• Office and business management: o Remote access to office applications o Email and communication on the go o Mobile payment processing o Calendar
• Education: o E-books and digital textbooks o Educational apps and tools o Note-taking and research
• Gaming and entertainment: o Mobile gaming apps o Streaming movies and music o Social media
• Remotely controlled devices: o Controlling smart home devices o Remote access to surveillance systems

o Controlling drones and other devices

• Communication: o Video calling o Text messaging
• Other: o Sat Nav o Online banking o Searching the Internet o Taking photos o Language translation Advantages and Disadvantages Advantages Disadvantages Easy to carry and use on the go (Portability) Limited expandability (Difficult to upgrade hardware) Access to internet and resources from anywhere (Flexibility) Less powerful (Lower performance compared to desktop computers) Can be used for various tasks and activities (Multi-functionality) Shorter battery life (Needs frequent charging) Emerging Technologies

AI (Artificial intelligence)

• This is the development of computer systems that can perform tasks usually requiring human intelligence, such as visual perception, speech recognition, and decision-making Impact of Artificial Intelligence (AI)
• Enhances productivity by automating repetitive tasks
• Improves decision-making through data analysis and pattern recognition
• Can be used in various industries, such as healthcare, finance, and transportation
• Raises ethical concerns, including job displacement and privacy issues

VR & AR

• Virtual Reality (VR): o A computer-generated simulation of a three-dimensional replicated environment o It can be interacted with in a seemingly real or physical way o Can manipulate objects or perform a series of actions

Hubs

• Hubs are devices that allow several other devices to be connected to them
• Hubs are generally much cheaper than switches but: o When a hub receives a data packet it will broadcast it to every device on the network
• This creates two potential issues: o As the information is being broadcast to every device it will make unnecessary traffic especially if there are a large number of devices o As every device will receive the data packet, security may be a concern Switches
• Switches are also used to connect several devices together just like a hub; however, rather than sending data packets to all devices on the network, the switch will only send the data to its intended device

• This is done by each switch having a lookup table Port Mac address 1 DF- 42 - B2- 11 - 4D-E 2 11 - 14 - F2-1D-C3-C 3 00 - 4B- 17 - 7C-A2-C
• When a switch receives a data packet , it examines the destination MAC address of the box and looks up that address in its l ookup table
• Once it has found the matching MAC address it will then forward the data packet to the corresponding port Bridges
• Bridges are used to connect two networks or network segments to create a single larger network
• An important note is that a bridge cannot communicate with external networks such as the internet like a router can

Bluetooth Wi-Fi Maximum number of connections

30 (based on a standard consumer grade router with high end options providing substantially more) Transmission frequency 2.4Ghz 2.4Ghz, 5Ghz Maximum range (meters) 30 meters 100 meters (depending on obstructions) Maximum transfer speed (Depending on the standard being used) 3 Mbytes / Sec 75 Mbytes / Sec

Cloud Computing

• Cloud computing is a method where data is stored on remote servers and accessed through the internet
• Local storage refers to a storage device that is connected to the computer
• The three types of cloud storage are: o Public Cloud - The customer and the cloud storage provider are different companies o Private Cloud - The customer and the cloud storage provider are a single organisation

o Hybrid Cloud - Combines both public and private cloud options and allows for sensitive data to remain private whilst providing public cloud services for less sensitive information

• Cloud data is duplicated and stored on other servers to ensure data availability during system failures, upgrades and maintenance periods Advantages of Cloud storage
• Scalability o As the business requirements change the customer can scale services up or down to meet their needs
• Cost saving o Cloud storage eliminates the need for a business to purchase expensive equipment for infrastructure and maintenance which can result in significant cost savings
• Accessibility o Cloud services are available globally and allow both remote working and data sharing
• Reliability o Cloud computing providers offer high levels of uptime ensuring that services are always available for its users
• Storage Space o Cloud services can offer an almost unlimited amount of storage
• Backup and recovery o If a customers machine or storage device fails, a backup of the data from the cloud will allow for recovery
• File Synchronisation o Files can be synced across multiple devices
• Convenience o A user does not need to carry storage devices around with them as all data is stored on the cloud Disadvantages of Cloud Storage
• Internet Connection o A stable internet connection is required to use cloud storage
• Security o Storing data in the cloud may be vulnerable to security breaches
• Dependency o The user is dependent on the storage provider for the availability and reliability of its services
• Ceases to trade/dissolve o Should the company dissolve or cease to change, all cloud data may be lost
• Cost