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Information Technology Unit 1 Digital BASICS Digital all devices ex. Number of colors in the computer (countable) Vs. Analogthe world around us ex. Infinite colors in the world (uncountable) Representing Data Data Representation refers to the form in which data is stored, processed, and transmitted. Digitization is the process of converting text, numbers, sound, photos, and video into data that can be processed by digital devices The 0s and 1s used to represent digital data are referred to as binary digits – from this term we get the word bit which stands for binary digit Representing Numbers Digital devices represent numeric data using the binary number system, also called base 2. The binary number system only has two digits: 0 and 1. No numeral like 2 exists in the system, so the number “two” is represented in binary as 10 (pronounced “one zero”) Representing Text Digital devices employ several types of codes to represent character data, including ASCII, Unicode and their variants. ASCII (American Standard Code for Information Interchange, pronounced “ASK ee”) requires seven bits for each character. Ex: The ASCII code for an uppercase A is 1000001 Extended ASCII is a superset of ASCII that uses eight bits for each character Ex: Extended ASCII represents the uppercase letter A as 01000001. Unicode (pronounced “YOU ni code”) uses sixteen bits and provides codes or 65,000 characters. ASCII text files contain no formatting. To create documents with styles and formats, formatting codes have to be embedded in the text. Examples: Microsoft Word produces formatted text and creates documents in DOCX format. Adobe Acrobat produces documents in PDF format. HTML markup language used for Web pages produces documents in HTML format Bits and Bytes All of the data stored and transmitted by digital devices is encoded as bits. The word bit, an abbreviation for binary digit, can be further abbreviated as a lowercase b. A group of eight bits is called a byte and is usually abbreviated as an uppercase B. Use bits for data rates, such as Internet connection speeds, and movie download speeds. Use bytes for file sizes and storage capacities. Compression To reduce file size and transmission times, digital data can be compressed Data compression refers to any technique that recodes the data in a file so that it contains fewer bits Compression is commonly referred to as “zipping” Compression techniques have two categories: lossless and lossy. Lossless compression provides a way to compress data and reconstitute it into its original state; uncompressed data stays exactly the same as the original data. Lossy compression throws away some of the original data during the compression process; uncompressed data is not exactly the same as the original. Digital Audio Basics Digital audio is music, speech, and other sounds represented in binary format for use in digital devices. Sound waves are sampled many times per second by an analog todigital converter. A digitaltoanalog converter transforms the digital bits into analog sound waves. Ripping is a slang term that refers to the process of importing tracks from a CD or DVD to your computer’s hard disk The technical term for ripping music tracks is digital audio extraction. To play a digital audio file, you must use some type of audio software, such as: Audio Software, Audio Players or Audio Plugin. MIDI MIDI (Musical Instrument Digital Interface) specifies a standard way to store music data for synthesizers, electronic MIDI instruments, and computers MIDI messages are instructions that specify the pitch of a note, the point at which the note begins, the volume of the note, etc. Digitalized Speech Speech synthesis is the process by which machines produce sound that resembles spoken words. Speech recognition (or voice recognition) refers to the ability of a machine to understand spoken words. Bitmap Graphics A bitmap graphic is composed of a grid of tiny rectangular cells. Each cell is a picture element, commonly called a pixel. Each pixel is assigned a color, which is stored as a binary number. With eight bits used to represent each color value, one pixel requires 24 bits The number of colors available in a graphic is referred to as color depth Cameras, scanners, and graphics software offer a choice of bitmap formats, such as BMP, RAW, TIFF, JPEG, GIF, and PNG. The dimensions of the grid that forms a bitmap graphic are referred to as image resolution. Vector Graphics A vector graphic consists of a set of instructions for creating a picture Vector graphics include standard shapes such as circles and rectangles Vector graphics are used for line art, logos, simple illustrations, infographic elements, and diagrams created from scratch. Vector Graphics vs. Bitmap Graphics Resize better than bitmaps Require less storage space Not as realistic as bitmap images Editing an object is easier than in bitmap 3D Graphics 3D Graphics are based on vectors stored as a set of instructions describing the coordinates for lines and shapes in a threedimensional space Vectors form a wireframe that works like the framework for a tent The process of covering the wireframe surface with color and texture is called rendering The technique for adding light and shadows to a 3D image is called ray tracing. 3D graphics can be animated to produce special effects for movies or to create interactive, animated characters and environments for 3D computer games. Video Basics Digital video uses bits to store color and brightness data for each video frame, a process similar to storing the data for a series of bitmap images in which the color of each pixel is represented by a binary number. Digital cinematography is used in the motion picture industry; it captures moving images as bits, rather than on film Digital video displays bitmap images in rapid succession. Video resolutions can be expressed as width x height, as the horizontal resolution, or as the vertical resolution. Digital video for computers typically uses progressive scanning; digital television uses interlaced scanning Aspect ratio is the proportional relation between the width and height of an image or video frame Video Compression A codec (compressor/decompressor) is the software that compresses a video stream when a video is stored, and decompresses the file when the video is played. Compressor/decompressor software Image compression – frames of a video are compressed using lossy and lossless compression Interframe compression – stores only the pixels that change color from one frame to the next Video File Format Video files are stored in container formats that hold the compressed video stream and an audio stream MP4 , AVI, MOV, MPEG, WebM, ASF, VOB, and Ogg Theora are popular container formats Digital videos can be converted from one format to another through a process called transcoding. Unit 2 Information Technology N OTES Vocabulary Computers a multipurpose device that accepts input, processes data, stores data, and produces output, all according to a series of stored instructions Outputis the result produced by a computer. Input whatever is typed, submitted, or transmitted to a computer. Computer Program Set of instructions that tells the digital device how to carry out processing task. Programs form the software that sets up a computer to do a specific task. Stored program means that a series of instructions for computing a task can be loaded into a computer’s memory Application Software is a set of computer programs that helps a person carry out a task System software is to help the computer system monitor itself in order to function efficiently (an example of system software is a computer operating system or OS). Development tools are used for creating software applications, Web sites, operating systems, and utilities. Semiconductors such as silicon and germanium, are substances with properties between those of a conductor (like copper) and an insulator (like wood) System board houses all essential chips and provides connecting circuitry between them. Computers Computers run 3 main types of software: 1. Application Software 2. System software 3. Development tools Circuits and Chips An integrated circuit (IC) is a set of microscopic electronic circuits etched onto a thin slide of semiconducting material. The terms computer chip, microchip, and chip are commonly used to refer to integrated circuits. The electronic components of most digital devices are mounted on a circuit board called a system board, motherboard, or main board. Components In the computer industry the term form factor refers to the size and dimensions of a device or components, such as circuit boards and system units. The term system unit is tech speak for the part of a digital device that holds the system board. Maintenance Basic system unit maintenance is simple; keep the unit clean, prevent it from overheating, shield it from damage and protect it from electrical surges. Touchscreens collect fingerprints and are a breeding ground for bacteria, so it’s a good idea to clean them periodically. Don’t operate devices if hot!!! Enterprise Computers Types of “Big” computers are: Supercomputers Mainframes Servers These computers are used in businesses and government agencies. Personal Computers Personal computers can be classified as: Desktop Portable (tablets) Mobile devices (smart phones) Niche Devices Ebook readers Portable media players Game consoles Ex: Smart watches, Smart glasses, Smart appliances, Activity Trackers. Microprocessors A microprocessor is an integrated circuit designed to process instructions. It is the most important, and usually the most expensive, component of a digital device. Intel Corporation is the world’s largest chipmaker and supplies a sizeable percentage of the microprocessors that power desktops and laptops. Microprocessors can’t directly understand programming language, such as Java, so programs have to be converted into machine language that corresponds to the microprocessor’s instruction set. The ALU (arithmetic logic unit) is part of the microprocessor that performs arithmetic operations, such as addition and subtraction. The ALU uses registers to hold data that is being processed the microprocessor’s control unit fetches each instruction. The term instruction cycle refers to the process in which a computer executes a single instruction. Performance (microprocessor) A microprocessor’s performance is affected by several factors, including clock speed, number of cores, processing techniques, cache size, word size, and instruction set. A microprocessor that contains circuitry for more than one processing unit is called a multicore processor. With serial processing, the processor must complete all steps in the instruction cycle before it begins to execute the next instruction. When a processor begins to execute an instruction before it completes the previous instruction, it is using pipeline processing. Parallel processing executes more than one instruction at a time and works well with today’s multicore microprocessors. Random Access Memory RAM (random access memory) is a temporary holding area for data, application program instructions, and the operating system. In RAM, microscopic electronic parts called capacitors hold the bits that represent data. Most RAM is volatile, meaning it needs electrical power to hold data. ReadOnly Access Memory ROM (readonly memory) is a type of memory circuitry that is housed in a single integrated circuit on the system board. ROM contains a small set of instructions and data called the boot loader which tell a digital device how to start. Storage Basics A data storage system has two main components: a storage medium and a storage device. Storage medium – the disk, tape, CD, or DVD that contains data. Storage device – the mechanical apparatus that records and retrieves data from a storage medium. Magnetic Storage Magnetic storage represents data by magnetizing microscopic particles on a disk or tape surface. A hard disk drive contains one or more platters and their associated readwrite head. Hard disk drive specifications include: Access time – the average time it takes a computer to locate data on the storage medium and read it. Data transfer rate – the amount of data a storage device can move per second from the storage medium to RAM. Optical Storage CD, DVD, and Bluray (BD) technologies are classified as optical storage, which represents data as microscopic light and dark spots on the disc surface. The dark spots are called pits; the lighter, nonpitted surface areas of the disc are called lands. CD, DVD, and Bluray (BD) technologies are classified as optical storage, which represents data as microscopic light and dark spots on the disc surface The dark spots are called pits; the lighter, nonpitted surface areas of the disc are called lands Solid State Storage Solid state storage (sometimes called flash memory) stores data in erasable, rewritable circuitry, rather than on spinning disks or streaming tape. Once the data is stored it is nonvolatile, meaning the circuits retain data without an external power source. A solid state drive (SSD) is a package of flash memory that can be used as a substitute for a hard disk drive. A USB flash drive is a portable storage device that plugs directly into a computer’s system unit using a builtin USB connector. Cloud Storage Remote storage is housed on an external device that can be accessed from a network. Remote storage can also be available as an Internet service, in which case it is called cloud storage. Cloud storage is provided to individuals by services such as Apple iCloud, Microsoft OneDrive, Google Drive, and Dropbox. Back Up A backup is a copy of one or more files that is made in case the originals become damaged or lost. Back Up tools include: Recovery Drive, Copy Command, File History, and System Image. Expansion Ports Many digital devices have ports in the system unit for connecting cables and various addons; these ports are called expansion ports because they expand the options for input, output, and storage. Blue Tooth Bluetooth is a lowpower technology, so it is ideal for mobile devices that don’t have big batteries. Bluetooth is used to connect wireless headsets to smartphones and is built into many smartphones, tablets, laptops, and desktops. Device Drivers and Apps A device driver is software that helps a peripheral device establish communication with its host device. Ex: the device driver for an HP printer sets up data streams from RAM to the printer and makes sure that the data is formatted in a way that the printer can work. Display Devices A computer display device that simply displays text and images is classified as an output device. Touchscreens, however, can be classified as both input and output devices because they accept input and also display output. LCD (liquid crystal display) technology produces an image by filtering light through a layer of liquid crystal cells. Screen size – the measurement in inches from one corner of the screen diagonally across to the opposite corner Response rate – the time it takes for one pixel to change from black to white then back to black Dot pitch (dp) – The LED’s that form an image on the screen are spaced in a grid; dp is the distance in millimeters between like colored LEDs Screen resolution – The number of horizontal and vertical pixels that a device displays on the screen One type of graphics circuitry, referred to as integrated graphics, is built into a computer’s system board. A second option, called dedicated graphics, is graphics circuitry mounted on a small circuit board called a graphics card (or video card). Printers An ink jet printer has a nozzlelike print head that sprays ink onto paper to form characters and graphics. Happy Studying!!!!! Unit 3 Information Technology NOTES Communication Systems A communication network (or communication system) links together devices to data and information can be shared among them. A communication channel is the medium used to transport information from one network device to another. Wired channels transport data through wires and cables. Wireless channels transport data from one device to another without the use of cable or wires. Microwaves are electromagnetic signals that can be aimed in a single direction and have more carrying capacity than radio waves. Advantages of wireless 1. Mobility 2. No unsightly cables 3. Less susceptible to power spikes Disadvantages of wireless 1. Speed 2. Range 3. Security 4. Licensing Bandwidth is the transmission capacity of a communication channel. Network channels that are capable of moving at least two megabits of data per second (2 Mbps) are classified as broadband. Channels slower than 2 Mbps are classified as narrowband. Network Nodes Any device on a network is called a node. Devices on a network are classified as DTEs or DCEs. A router is a device that controls the flow of data within a network and also acts as a gateway to pass data from one network to another. A modem contains circuitry that converts the datacarrying signals from a digital device to signals that can travel over various communications channels. Communication Protocol In the context of networks, a communication protocol refers to a set of rules for efficiently transmitting data from one network node to another. This process is called handshaking. Networks use more than one protocol, and the collection of protocols for a network is referred to as a protocol stack. Background The ARPANET, created in 1969, connected computers at UCLA, the Stanford Research Institute, the University of Utah, and UC California at Santa Barbara. Internet governance is simply a set of shared protocols, procedures, and technologies that evolve through common agreement among network providers The organization that supervises internet addressing is ICANN, the Internet Corporation for Assigned Names and Numbers Internet Infrastructure The way networks fit together is referred to as the Internet Infrastructure. Networks that form the Internet are maintained by Internet service providers (ISPs) ISPs exchange data at Internet exchange points (IXPs) Packets A packet is a parcel of data that is sent across a computer network; when packets reach their destination, they are reassembled into the original message according to their sequence numbers. Communication networks use a technology called circuit switching, which establishes a private link between one telephone and another for the duration of a call. A more efficient alterative to this process is packet switching technology, which divides a message into several packets that can be routed independently to their destination. One of the core Internet protocols, TCP (Transmission Control Protocol) is responsible for dividing files into chunks, adding headers containing information for reassembling packets in their original order, and verifying that the data was not corrupted while in transit (a process called error checking) UDP (User Datagram Protocol) is an alternative transport protocol which is faster than a TCP but does not perform error checking and cannot reorder packets. A communication port (usually referred to simply as a port) is a virtual end point for data entering and leaving a digital device. Internet Addresses Internet Addresses are controlled by IP (Internet Protocol), which is part of the Internet protocol suite. Many devices on the Internet have permanently assigned IP addresses called static addresses. Internet addresses that are temporarily assigned to a device are called dynamic addresses. IP addresses can be assigned by a network administrator, but more commonly they are automatically assigned by DHCP (Dynamic Host Configuration Protocol). A private IP address can be allocated by any network without supervision from ICANN – but it cannot be used to send data over the Internet; it’s not routable. The local router has a public IP address that is routable over the Internet. Domain Names It’s hard to remember the string of numbers in an IP address; most Internet destinations also have an easytoremember domain name, such as nike.com. The mechanism for tracking domain names and their corresponding IP addresses is called the domain name system (DNS). A domain name ends with an extension that indicates its toplevel domain, such as .edu or .org. Domain name servers are scattered around the world and maintain lists of all domain names and their corresponding IP addresses. Unauthorized changes to the DNS are called DNS spoofing. Connection Basics The most common measurement of connection speed is the amount of data that can be transmitted in a specified time; technically, it is a measure of capacity. Your bandwidth cap is the top speed allowed by your plan. During peak times, ISPs can place further limits on speed, a process called bandwidth throttling. When Internet upload speed differs from download speed, you have an asymmetric connection. When upload and download speeds are the same, you have a symmetric connection. Ping is utility software designed to measure responsiveness Ping rate indicates how quickly data can reach a server and bounce back to you Latency is the elapsed time for data to make a roundtrip from point A to point B and back to point A Jitter measures the variability of packet latency caused when network traffic and interference can delay packets and create erratic data flow Packet loss refers to data that never reaches its destination or gets discarded because it arrives too late Cable Internet Service The gold standard of fixed Internet access is cable Internet service, which is offered by the same companies that supply cable television. CATV stands for community antenna television. CATV coaxial and fiberoptic cables have plenty of bandwidth to carry television signals for hundreds of channels in addition to digital data. Telephone Internet Service A dialup connection is a fixed Internet connection that uses a voiceband modem and the telephone company’s circuitswitched network to transport data between your computer and your ISP. A voiceband modem converts digital signals from a computer into audible analog signals that can travel over telephone lines. ISDN stands for Integrated Services Digital Network; it divides a telephone line into two channels, one for data and one for voice, by using packet switching. DSL (digital subscriber line) is a highspeed, digital, alwayson, Internet access technology that runs over standard phone lines; it’s offered by AT&T’s Uverse service. FTTH (fibertothehome) is the use of highcapacity fiberoptic cables, rather than coaxial cables, to connect homes to broader municipal networks. Satellite Internet Service Satellite Internet service is a means of distributing broadband asymmetric Internet access by broadcasting signals to a satellite. In many rural areas, satellite Internet service is the only alternative to a slow dialup connection. Mobile Broadband Service Mobile broadband has evolved through several generations; the most recent of these generations are 3G and 4G. Most of today’s smartphones include a tethering feature that connects wirelessly with other digital devices. Wifihotspots The network has an Internet connection and device called an access point that broadcasts WiFi signals within a range of about 150 feet. LAN Basics Local area networks are often referred to as LANs. The Windows OS provides a tool for setting up a LAN called a homegroup; this makes it easy to share files among local computers, but does not provide Internet access. The circuitry that enables a device to access a LAN is called a network interface controller (NIC). NICs contain a MAC address (media access control address) used to identify devices on LANs. Ethernet Ethernet is a wired network technology that is defined by IEEE 802.3 standards. Today’s Ethernet LANs are usually arranged in a star topology with computers wired to central switching circuitry that is incorporated in modern routers. IoT Networks The Internet of Things (IoT) connects active sensors and passive tags to communications networks, making it easy to remotely monitor places and things. Existing wireless technologies such as RFID and NFC offer potential solutions. Additional lowpower shortrange technologies developed specifically for IoT networks include Bluetooth Smart, ZigBee, and ZWave. File Sharing Basics Permissions specify how shared files can be used like, readonly, writeonly, etc. FTP (File Transfer Protocol) provides a way to transfer files from one computer to another over any TCP/IP network, such as a LAN or the Internet. Dropbox and similar file hosting services store files in the cloud. Torrents BitTorrent is a file sharing protocol that distributes the role of a file server across a collection of dispersed computers. A BitTorrent network server breaks a movie file into pieces and begins to download those pieces to the first computer that requested the movie.