G8 ICT Notes [RCS] PDF

BIOS [Basic Input Output System] mouse monitor [CRT, TFT] SD card keyboard speakers SSD [solid state drive] microphone printer [laser, inkjet, 3D] pen drive...

BIOS [Basic Input Output System] mouse monitor [CRT, TFT] SD card keyboard speakers SSD [solid state drive] microphone printer [laser, inkjet, 3D] pen drive/usb stick touchscreen projector CD trackpad DVD webcam HDD [hard disk drive] scanner SSHD [solid state joystick hybrid drive] Made of keys which are arranged into different sections [alphabet, function, numeric, arrow, command] Advantages: Requires no training, allows you to enter data very quickly, easy to use Disadvantages: Easy to make spelling errors, not suitable for creating diagrams Enables you to control what happens on the screen by moving the mouse on your desk and pointing, clicking and selecting items on the screen Advantages: Computers are familiar, works with a keyboard, fast to use, easy to learn Disadvantages: Requires a flat surface near the computer, wireless mice have to be charged, old mice might get clogged due to the roller ball and lose their accuracy Only device that is both input and output Examples: Phone, tablet/iPad, kiosks, computers, ATM Advantages: Easy to use, allows use of finger gestures Disadvantages: Not suitable for large amounts of data, inaccurate, tiring to use Special hardware known as ADC [Analog to Digital Converter] converts the sound waves from analog waves to digital signals so that the computer can understand it Advantages: Captures audio for recording and communication, versatile, easy to use Disadvantages: Sensitive to background noise, may require additional equipment for optimal sound quality, can be inaccurate if used for dictating Captures the video image of a scene in front of it Built into computer or connected through USB cable Made up of ‘image frames’ which are an instant snapshot of the scene in front of it 6  Each image frame is sent to the computer for further processing If the 'frame rate' is fast enough [>25 frames per second] it appears as motion video Uses: chatting [teleconferencing], tourists [pointed towards scenes around the world for people to view], security [burglar alarm, capturing image if movement is detected] Advantages: Allows for real-time communication, better interactions Disadvantages: Can be affected by poor lighting, privacy concerns, internet dependent Automatic input reader device Scans/reads barcodes using red light since black absorbs light and white reflects it Series of vertical bars of varying width which gives information about ○ Country of manufacture ○ Name of manufacturer ○ Product code ○ Does not display the price [price only needs to be changed on the database] Uses: Retail stores, inventory management, libraries, shiping Advantages: Faster than QR codes, accurate, efficient Disadvantages: Can be expensive, won’t scan if damaged Contains a link that when scanned, will open to a website/file/social media account Data is encoded in a grid of black and white squares, scanner reads the pattern and decodes the information Uses: Make payments, access menus, check in for movies Advantages: Simple to use, fast, contactless, used across many industries, inexpensive Disadvantages: Requires a phone, some codes may not be scannable if they are misprinted, not always secure It interprets the pattern of the marks and sends the results to the computer It detects the presence of pencil marks by reflecting light onto it Uses: Scan MCQ papers, lottery tickets Advantages: Efficient [10,000 forms per hour], accurate, only needs one computer Disadvantages: Mark is too light or doesn’t fill the space correctly it can be misread, can only record selection answers and not text input, needs to be done on prepared forms and not on any paper Scans text from paper and transmits it to a computer Examines text and changes the handwriting into proper text Advantages: Cheap, fast, can recreate tables and layout Disadvantages: Not 100% accurate, needs to be checked, mistakes may occur based on quality of handwriting 7  Read data is encoded in magnetic stripes Can contain up to 60 characters Uses: Back of credit cards, cheque guarantee cards, loyalty cards, membership cards Advantages: Reliable, minimal setup, inexpensive, data can easily be altered Disadvantages: Limited storage capacity, not always secure, data can easily be destroyed Converts images or text on paper into a digital format that can be used by the computer Shines light onto the surface of the object, which is reflected back onto a sensor that detects the colour of the light Types: Flatbed [most commonly used], handheld, specialist Advantages: Accurate, high quality, images can be enhanced, can be added to documents Disadvantages: Takes up storage space, quality is dependent on original image LEDs [Light Emitting Diodes] controlled by computers via electrical signals [on/off] Control devices [lights, buzzers, motors] used in systems like traffic lights Icons are better than text: use less space, language-independent, suitable for global use Advantages: Cost effective way of indicating status of equipment, provide warning for users who can’t hear, different colors Disadvantages: Break, wear out, require replacement, loose connection can prevent light from turning on, can only show simple status [on/off] Most computers are fitted with a small internal speaker which can produce beeping sounds to alert you if you make an error Computers can also be fitted with a sound card [or chip] which will enable sound to be output through external speakers, producing a higher quality sound Advantages: Everyone in the room can hear the output, help create an atmosphere or ambiance, let blind people use computers because text can be converted into sound Disadvantages: Can disturb others, high quality speakers can be expensive, require significant power or space, performance varies Headphonesconsist of a pair of small loudspeakers which are worn over the ears Connected by cable or wirelessly to a device such as a computer, radio or MP3 player Transducer converts the electronic signals from the device into sounds which can be heard by the user via the phones Advantages: Can only be heard by user, lightweight, portable, inexpensive Disadvantages: Risk of permanent hearing loss, unaware of surrounding noises, uncomfortable, not easy to move around 8  Uses laser beam technology Computer sends data to printer → printer cleans the drum → drum and paper are charged with static electricity → laser beam scans drum to generate an invisible image → toner powder adheres to the modified areas of the drum → toner particles are attracted to the paper using positive and negative charges → heat and pressure fuse the toner to the paper, with excess toner being recycled Brands: HP, Brother, Epson Advantages: Fast, quiet, cost per page is low, high quality text and graphics on paper Disadvantages: Toner is expensive, large, can’t use multipart stationary to create carbon copies Uses a hydraulic system to spray a personified ink over paper using microscopic nozzles which produces sharp and colourful images. They can print on different types of media materials Print head has tiny nozzles known as jets Paper moves past the print head → nozzles spray ink on it which form the images It can produce from 100 to several hundred pages, depending on the nature of the hard copy, before the ink cartridges need refilling It usually has one black ink cartridge and one colour inkjet cartridge with cyan, magenta and yellow ink Can also be used as a scanner, photocopier and fax machine along with a printer Brands: Epson XP, Canon Pixma, HP Deskjet/Officejet Advantages: Cheap, compact, cartridges are cheap, good quality Disadvantages: Noisy, slow, cost per page is high, cartridges need to be replaced often, ink can smudge, colors look different on paper, cartridges may dry out No nozzle Nozzle from which ink is sprayed Ink is toner [powder] Ink is liquid, and can dry out Ink doesn’t need refilling for long time Ink needs refilling in short time Expensive at first but doesn’t need Originally not expensive, but over require many additional costs time it adds up Better for text or normal documents Better for colourful printouts Most common output device Typical monitors are 19 inch diagonal Pictures shown on monitors are made up of pixels ○ The more pixels, the better picture quality ○ Comprised of RGB which mixes to form other colours 9  ○ Resolution: the total number of pixels displayed on the screen [every screen has a specific amount of pixels it can display] There are TV screens up to 60 inches available Standard TV screen is 720 pixels down and 1280 pixels across which is better for video and not as great for text Some screens are 1080 pixels down and 1920 pixels across which is better for displaying text, and for HD [High Definition] and Blu-ray content Uses: Home, public areas for ads, screens in video conferencing Advantages: Large screen, thin, good viewing angle, bright, not affected by magnetism, can be mounted on wall, better for eyes than laptop Disadvantages: Standard resolution is not good, has to be viewed from a distance, need a lot of space, expensive The primary or main memory holds the data and information during processing. It holds data temporarily, as we switch off the computer the information vanishes. Temporary memory of a computer Data can be read from and written to the RAM by the CPU [direct connection] Loses all data when power is turned off [volatile] Stores the operating system, applications, and data currently in use Immediate access store [IAS] More RAM a computer has, the faster it can process tasks Advantages: Faster than HDDs or SSDs Disadvantages: Does not store data for long amount of time Stores permanent data [system’s firmware, basic input output system] Data can only be read [cannot be changed] Retains crucial information even when the power is turned off [non-volatile] Advantages: Permanent Disadvantages: Unable to be edited It can store data permanently on the computer but it cannot process data. It is meant for permanent storage of data and information. Uses spinning magnetic platters to read and write data Found in desktop computers and some laptops Used for storing large amounts of data like operating systems, applications, and files 10  Advantages: Large storage capacity at a low cost, reliable for long-term storage Disadvantages: Slower than SSDs, prone to damage due to moving parts, heavy, bulky Uses flash memory to store data with no moving parts Advantages: Faster than HDDs, durable, energy-efficient, shock-resistant, light, compact Disadvantages: More expensive than HDDs per gigabyte, limited number of write cycles External HDDs & SSDs [large data storage and backups] USB flash drives/pen drives [portable, used for quick file transfers] Uses magnetic strips to store data, typically used with tape drives Used in data archiving and backups in data centers Advantages: High storage at low cost, reliable for long-term data, compact, easy to store Disadvantages: Slow data access due to sequential reading, requires specialized hardware for use, not suitable for quick or frequent access Devices that read or write data on optical discs like CDs, DVDs, or Blu-rays Used in media distribution, backups, and software installation Advantages: Affordable and widely available, good for distributing media like music and movies, non-magnetic, so immune to magnetic interference Disadvantages: Limited storage capacity compared to modern storage devices, fragile, scratched, degrade over time, obsolete with the rise of modern storage technologies Optical drives that read or write data on CDs Primarily for music, software distribution, and small data storage Advantages: Affordable and easy to produce, common format for music and software distribution, non-magnetic, immune to magnetic interference Disadvantages: Limited storage [700MB], easily scratched or damaged, slower read/write speeds compared to modern storage devices. Optical drives that read or write data on DVDs Common for video storage, larger software distribution, and backups Advantages: Higher storage than CDs [4.7GB], affordable, widely used, reliable Disadvantages: Susceptible to physical damage, slow transfer rates compared to newer technology, outdated with streaming and cloud storage options External storage devices [HDD or SSD] used for data transfer and backup 11  Used in backups, file transfers, and additional storage for personal/professional use Advantages: High storage capacity for both variants, portable, easy to use, compatible Disadvantages: HDD variants can be slower and prone to damage, SSD variants are more expensive, can be lost or stolen Flash memory storage devices that connect via USB ports Portable storage for data transfer between computers, backups, quick file sharing Advantages: Compact, portable, easy to use, high storage [TB], fast read/write speeds Disadvantages: Can be corrupted, easy to lose, slower than external hard drives Flash memory cards used in cameras, smartphones, and other portable devices Stores photos, videos, music, apps in smartphones, cameras, and portable game consoles Advantages: Small, portable, high storage capacity, versatile Disadvantages: Prone to corruption, slower transfer speeds, physical wear and tear Electronic device which can perform various operations quickly and accurately [eg. data processing, large calculations] Work on electricity, currents, and signals ○ Electric signals [on/off] When a current is passed, it is on When a current is not passed, it is off ○ 2 types of currents: AC [Alternating] DC [Direct] Fast, executes millions of Cannot make decisions instructions/sec Only understands binary language High storage capacity [data in one Cannot work without electricity place] Does not have its own intelligence Versatile as it can do many tasks Makes no mistakes Most powerful computers among digital computers Consists of several processors running together that makes it faster Has a capability equal to that of 40,000 microcomputers Used for nuclear research Eg. PARAM and ANURAG 12  Very large computers available in different models, capacities, and prices Qualified operators and programmers are required for their operation Support a wide range of peripherals Have large storage capacities Make use of a wide variety of software Mainly used in large commercial and government organizations Less capacity to manipulate and store data compared to mainframe computers Limited range of peripherals Limited software can be used Widely used for data processing Air conditioning is not necessary but is provided for dust control Use one or more microprocessors Contain storage and input/output facilities Cheap and easy to use Limited input, output, and storage capacities Visual Display Unit [VDU] or printer is used to get the output Process of restarting a computer or its operating system software Cold Booting: When the computer is started after having been switched off Hot Booting: When the operating system is restarted after a system crash or freeze 13  Viruses Anti-Malware Worms Anti-Virus Trojan horses Encryption Spyware Acceptable use policies Adware Backup/recovery procedures Ransomware Unauthorized access, manipulation, or exploitation of computer systems, networks, or devices, with activities from malicious intent to ethical efforts to enhance security. Leads to identity theft, theft of money, theft of personal information. Data can be deleted, changed, corrupted. Solutions: Firewalls, strong passwords, anti-hacking software. Malicious software Executable programs that run on a computer [computer virus] Can replicate code, infect computers, corrupt/delete/modify files Many types of malware, such as worms, trojan horses, ransomware, spyware and adware Replicates itself to spread to other computers Slows down networks/computers There is a program/game/file that the user wants Negative program code, causes damage, takes control, or provides access to the computer Type of malware that first encrypts the hard drive of the computer This means the user is unable to read the files on the computer/run programs In order to get control back, they usually have to pay a ransom, usually of cryptocurrency If they pay the ransom their files will be restored, otherwise they will be deleted This is a type of malware that finds out information about a user/computer/company The information is sent to a hacker [who can misuse it] The spyware can be hidden inside an app, file attachment or website 17  Displays large numbers of adverts [multiple tabs/windows] Sometimes new adverts appear faster than the user is able to close them The hacker aims to make money from users clicking on the adverts Type of social engineering technique Emails, texts or phone calls are sent to users commonly pretending to be from a bank or website [the “from” address can be forged] Messages will try to get personal information [usernames, passwords, credit card details] Solutions: Don’t open unknown emails/links, don’t give information over email, use anti-phishing tools Avoiding Phishing Greeting: Phishers don’t know your name, just your email address, greeting is generic Address: The sender’s address is often a variation on a genuine address Forged link: Link looks genuine, but the URL attached to it may not link to the website given [roll your mouse over it to check] Request for personal information: Genuine organisations never do this over email Sense of urgency: They tell you that something bad will happen if you don’t act fast Term comes from the words phishing and farming Users computer/DNS server altered so match a domain name to an incorrect IP address Browser searches for a web page, goes to wrong IP address which is controlled by hacker Hacker will have a web server [fake web page], like a form for a user’s bank account User enters his username and password to login, the hacker will gain the information Solutions: Check if green padlock present in URL bar, check HTTPS, use anti-virus tools Type of phishing Uses text messages [SMS] to deceive people into sharing sensitive information Ability to gain confidential information by asking people for it Crime where someone wrongfully acquires/uses another person’s personal information For financial gain/fraudulent activities Hackers try to guess your passwords by trying combinations of letters/numbers/symbols Gets access to user’s personal data [credit cards, passwords and more] Solution: Stronger passwords 18  Stealing data by tapping into a wired/wireless transmission line Uses packet sniffers to examine packets sent over a line Collected data is sent back to attacker Can cause computer to crash, can delete or corrupt files/data Solutions: Anti-virus software, don’t use software from unknown sources Mimics a severe traffic jam but digitally Floods target system with excessive traffic from compromised devices Overwhelms resources so the system is unresponsive to legitimate requests For businesses it can cause financial loss, reputational damage, and potential data loss Unpatched Software: Software/security updates not installed then software is vulnerable Out-of-date anti-malware: Software, such as antivirus software, isn’t regularly updated then it won’t be able to detect the latest viruses Anti-malware, anti-virus and anti-spyware software will detect malware such as viruses, worms, trojans, and spyware ○ Virus or new malware is detected and is sent to the anti-virus company ○ They verify it is malware then create a signature of the virus ○ They add it to their virus database and tell computers to run an update Viruses can morph to avoid detection, making it harder to create a signature Encryption is a way of securing data so that it cannot be read without the encryption key ○ Passwords stored by websites are usually stored in an encrypted form ○ If hacker obtains the data in password database, won’t be able to read it ○ Devices and computers can also have their storage and hard disk data encrypted Websites using HTTPS encrypt the connection to the server ○ Your web browser sends its key and form data, encrypting it with the server’s key Protocol that ensures cryptography is used when transmitting web pages ○ SSL makes your website safe ○ SSL certificates are purchased by the owners of websites, verifying website owner ○ Clicking on padlock in browser address bar usually allows you to view the certificate 19  Separate a trusted network from an untrusted network [normally the Internet] Data is sent around a network in small packets of information These packets are checked to see where they are coming from and going to ○ Packets that don’t match filtering rules are dropped [packet filter] Firewalls can be run on dedicated hardware or as software Can be built into your hardware ○ May be a dedicated unit to the task of being a firewall ○ Can be built into other devices such as a home Wi-Fi router ○ Dedicated hardware firewalls are expensive ○ Prevents attackers from gaining access to computers on a network ○ Blocks certain malicious computers by filtering packets from a certain IP address ○ Can prevent access to certain ports on the network [port blocking] ○ Malicious or inappropriate websites can be blocked ○ Software firewalls will slow down a computer Access rights may be set on disks, folders and even individual files When using the Internet is that you need to reveal the IP address of your computer ○ Instead, requests may be made to a proxy server which makes requests to the server on your behalf, keeping your IP address hidden ○ May be carried out by proxy server in an office or Virtual Private Network [VPN] ○ If you use a public network, such as in a café or hotel, you should make use of a proxy server [this is usually a paid for service] Privacy settings allow you to turn off computer features to reduce the risk of hacking attempts or personal data being stolen Turning off microphone, webcam/camera, preventing websites accessing location data, preventing websites tracking you, blocking cookies Usernames/passwords are important ways of protecting computers and servers They prevent unauthorised people from using the system They also apply the correct access permissions to the user’s account Strong passwords include at least one symbol, lowercase and uppercase letter You should change your password frequently Biometrics measure a person’s physical characteristics to verify their identity One common method of authentication used on portable devices is a fingerprint ○ Facial recognition [commonly now used on personal devices] ○ Retinal scans [more commonly used in high security environments] 20  Large companies such as Microsoft and Adobe automatically update your software whenever they make a change to it Software updates are necessary to fix bugs, patch security holes Virus software needs to be set to auto-update so that it always has latest virus definitions Operating systems should either auto-update, or be updated as soon as security updates Act of searching for and identifying Wi-Fi networks Often with specialized equipment to detect and map wireless networks, including potential security vulnerabilities 21