Lec 2 B.pdf

Starting a computer Turn on the power button on the system Unit then turn on the power button of the monitor or visual display unit. Booting This is the process by which the computer loads system files into the main memory. This process involves carrying out diagnostics...

Starting a computer Turn on the power button on the system Unit then turn on the power button of the monitor or visual display unit. Booting This is the process by which the computer loads system files into the main memory. This process involves carrying out diagnostics test. Or is the process of starting or restarting a computer. Types of booting 1. Cold booting. This is the starting up of the computer which has not been on by turning on power buttons. 2. Warm booting This is the restarting of the computer. It is known as system reset which can be done by processing the resetting button. Files and folders A file is collection related information that is given a name and stored so that it can be retrieved when needed. File names can contain two characters including spaces. A folder is a collection of files. A folder can also contain many sub-folders Creating a folder Right click on the desktop From the sub menu choose New then click on folder By default a new folder will be created with a tittle new folder Type the name of the new folder and press ENTER. Renaming a folder Click the right button on the mouse and select rename. Or Press F2 from the keyboard Deleting a folder Select or (click on the file). Then press delete on the keyboard From the message box “Are sure you want to delete the folder” click OK How to retrieve deleted files Double click on recycle bin icon and click on file you want to retrieve. It will be restored back to its original location. Open the recycle Bin, Right click on the folder / file you want to restore. From the sub menu click on Restore. 12  HARDWARE These comprises of physical, electronic, electric and mechanical components of a computer that help it to process data. They can also be defined as parts / components of a computer that are tangible and occupy space. OR Hardware refers to any physical or tangible part of a computer. Hardware is categorized into internal hardware and externa hardware, Where Internal hardware components are components found inside the system unit like disk drives, motherboard, memory etc And External hardware (peripherals) are external devices connected to the central housing. These components include input devices, output devices, a system storage devices and communication devices. Qn: What is the difference between Computer Hardware and Computer Peripherals? Computer hardware refers to the physical components of a computer that can be touched. While A peripheral is a device attached to a host computer but not part of it whose primary functionality is to expand the host’s capabilities. A peripheral device is not part of the system's core architecture but attached to the computer by using ports. The Illustration below shows the most common hardware. 13  Hardware that is not part of the system unit is sometimes called a peripheral device or device. INPUT DEVICES An input device is any hardware component that allows you to enter data or instructions into the computer Six widely used input devices are the keyboard, mouse, microphone, scanner, digital camera and PC video camera. Mouse. Is a pointing device used to manipulate on screen objects. A mouse is a small hand held device used for pointing. A mouse moves a pointer on the computer screen. Basic parts A mouse typically has two buttons: a primary button (usually the left button) and a secondary button (usually the right button). The primary button is the one you will use most often. Most mice also include a scroll wheel between the buttons to help you scroll through documents and web pages more easily. On some mice, the scroll wheel can be pressed to act as a third button. 14  Mouse operations  Clicking (single-clicking): This is the act of pressing a computer mouse button once without moving the mouse and it’s the primary action of the mouse.  Double-clicking: This is the action of quickly pressing and releasing the left mouse button twice in succession. Its commonly used to perform tasks like opening files, folders or applications on the computer.  Drag:This the action of pressing and holding down a mouse button usually the left button then move the mouse while keeping the button pressed and finally releasing the button to drop the selected item. Tips for using your mouse safely.  Place your mouse at elbow level.  Don't squeeze or grip the mouse tightly.  Move the mouse by pivoting your arm at your elbow.  Use a light touch when clicking a mouse button.  Keep your fingers relaxed. Don't allow them to hover just above the buttons.  When you don't need to use the mouse, don't hold it.  Take short breaks from computer use every 15 to 20 minutes Other pointing devices / variants of the mouse  Track ball. A track ball is a stationary pointing device with a ball onto its top. Its commonly used in gaming, video editing and animation, computer aided design (CAD) etc  Touchpad. A touchpad is a small, flat, rectangular pointing device that is sensitive to pressure and motion. To move the pointer using a touchpad, slide your fingertip across the surface of a pad. 21   Joystick and wheel. A joy stick is a vertical lever mounted on a base. You move the lever in different directions to control the actions of the simulated vehicle or players. Commonly used in gaming, flight simulation and aviation, Robotics control etc  Pointer stick. A pointer stick is a pressure-sensitive pointing device shaped like a. pencil eraser that is positioned between keys on a keyboard.  Light pen. A light pen is a handheld input device that can detect the presence of light. Used for Computer Aided Designe (CAD), graphic design and drawing etc  Touch screen. A touch user's screen is a touch-sensitive display device. Users interact with these devices by touching areas of the screens. Keyboard A keyboard is an input device that contains keys users press to enter data into a computer. This is an input device comprising of alphabetical letters, numbers and other keys used to enter data into a 22  computer. Many computer keyboards have got four sections.  Typing keys (Alphabetical key pad): Which include letters of the alphabet, numbers, punctuation marks, and other basic keys.  Numeric key pad: on the right side of the keyboard.  Functional Keys: which are labeled with the letter F followed by a number eg Fl, F2,F12 etc  Special keys on the keyboard 1. Enter Key (Execute key). It is used to accept a command or execute a command. Or it is used to go to another line when typing, 2. Back space key. It is used to erase / rub characters to the left side of the cursor. 3. Space bar. It is the longest key on the keyboard and it is used to insert spaces between word and characters. 4. Caps lock. It is used to turn capital letters into small letters and small letters into capital letters. When the caps lock is pressed a caps lock light on the top right corner is turned on to indicate that you are in capital letters to switch to small letters press the caps lock button again, 5. Shift key. It is used to activate characters on top of the buttons, it can also turn in either small letters or capital letters dependin g on the keyboard case mode. 6. Delete key. It is used to erase characters on the right side of the cursor. 7. Fl: It is used as help. 8. Esc (escape): it is used to cancel an application under taken. Other input devices Scanner. This is a light-sensing input device that reads printed text and graphics and translates the results into a form a computer can process. Digital camera. It allows users to take pictures and store the photographed images digitally Instead of on traditional film. Web cam. This is a video camera that displays it's output on a web page. Its commonly used in livestreaming, 23  online teaching and learning, video conferencing and online meeting etc Touch Screen. A touch screen is a special kind of input device that allows the direct selection of a menu item or the desired icon with the touch of finger. Essentially, it registers the input when a finger or other object is touched to the screen Bar code reader. Bar code is a machine-readable code in the form of a pattern of parallel vertical lines of varying widths. It is commonly used for labeling goods that are available in super markets and numbering books in libraries. This code is sensed and read by a bar code reader using reflective light. The information recorded in bar code reader is then fed into the computer, which recognizes the information from the thickness and spacing of bars. OUTPUT DEVICES This is any type of hardware component that conveys information one or more people. Commonly used output devices include display devices, printers, speakers and headsets, fax machines and fax modems, multifunction peripheral data projectors e.t.c. Output is data that has been processed into useful form. The computer processes input (data) into information (Output). 1. Hard Copy: The physical form of output is known as hard copy. OR it refers to the recorded information copied from a computer onto paper. Hard copy output is permanent and a relatively stable form of output. This type of output is also highly portable 2. Soft Copy: The electronic version of an output, which usually resides in computer memory and/or on disk, is known as soft copy. Unlike hard copy, soft copy is not a permanent form of output. It is transient (lasting for a short period of time) and is usually displayed on the screen. Following are few of the important output devices, which are used in Computer Systems: 24  Monitors Monitor commonly called as Visual Display Unit (VDU) is the main output device of a computer. It forms images from tiny dots, called pixels,that are arranged in a rectangular form. The sharpness of the image depends upon the number of the pixels. A pixel (short for "picture element") is the smallest unit of a digital image or display that can be individually controlled to represent a specific color or brightness. There are two kinds of viewing screen used for monitors:  Cathode-Ray Tube (CRT). The CRT is a large, heavy device that produces images through an electron beam striking a phosphorescent surface.  Flat-Panel Display Monitor: The flat-panel display refers to a class of video devices that have Reduced volume, weight and power requirement compared to the CRT. Current uses for flat-panel displays include calculators, video games, monitors, laptop computer, graphics display. The flat-panel display are divided into two categories: 1. Emissive Displays - The emissive displays are devices that convert electrical energy into light. Example are plasma panel and LED (Light-Emitting Diodes). 2. Non-Emissive Displays - The Non-emissive displays use optical effects to convert sunlight or light from some other source into graphics patterns. Example is LCD (Liquid-Crystal Device) Printers. A printer is an output device that converts digital documents, images, or text from a computer or other digital devices into a physical form usually on paper. The quality of a printer is determined by the clarity of a print it can produce, that is, its resolution. Printers are divided into two basic categories: Impact printers and non-impact printers. Impact printers work by physically striking a head or needle against an ink ribbon to make a mark on the paper. This includes dot matrix printers, daisy wheel printers, and drum printers. Non-impact printer is a type of printer that produces images and text on paper without physically striking the paper. Examples are inkjet and laser printers.. Factors considered before buying a printer  The number of pages per minute (ppm) the printer can print.  The memory size of the printer i.e. at least 2 MB 25   The price of the cartridge or tonner.  The availability of cartridge or tonner.  The price of the printer.  The purpose for which the printer is going to be put to use Advantages of Hard copy over soft copy  A hard copy can easily be accessed by both the rich and poor readers.  It cannot easily be changed without tracing.  It can be read off-line namely without a computer.  It is cheaper compared to softcopy, which requires computer devices to be able to read the information / data.  Hard copies last longer if stored in a safe place compared to softcopy Fax machines and Fax Modems A fax machine is a device that transmits and receives documents over telephone lines. A fax modem is a modem that allows you to send (and sometime receive) electronic documents as faxes Data projectors A data projector, often referred to as a projector, is a device used to display visual content, such as presentations, videos, or images, onto a larger screen or surface. Qn1: Mention devices which can be classified as both input and also output computer hardware. 1. Touch Screen 2. a hard disk drive - a device used for both reading and writing data to and from a Hard disk 3. USB flash drive - used for both reading and writing data to and from Flash disks 4. Modem 26  STORAGE Storage devices hold data, instruction and information for future use. A computer keeps data, instructions and information on storage media e.g. floppy diskette, zip disk, USB flash disk, Hard disk, memory cards and Tapes. Storage Capacity is the number of bytes (Characters) a storage medium can hold. Reading: is the process of transferring data, instructions and information from a storage medium into the memory. Writing: is the process of transferring items from memory to a storage medium. The speed of a storage media is defined by its access time, which is the amount of time it takes to locate an item on a storage medium. Primary Memory (Main Memory) Primary memory holds only those data and instructions on which computer is currently working on and it is directly accessed by the CPU. It has limited capacity and data gets lost when power is switched off. It is divided into two subcategories RAM and ROM. Characteristic of Main Memory  These are semiconductor memories.  Usually volatile memory.  Data is lost in case power is switched off.  It is working memory of the computer.  Faster than secondary memories. A RAM is read/write memory. It is called random access memory (RAM). RAM is volatile, i.e., data stored in it is lost when power is turned off or when there is a power failure. 27  Hence, a backup uninterruptible power system (UPS) is often used with computers. RAM is small, both in terms of its physical size and in the amount of data it can hold. ROM (Read-Only Memory) is a type of non-volatile memory used in computers and electronic devices to store firmware or permanent data that doesn't change during normal operation. ROM chip are not only used in the computer but also in other electronic items like washing machine and microwave oven. Firmware is a specialized type of software that is embedded into hardware devices to control and manage their functions. Secondary Memory This refers to storage devices that are used to save data and programs that are not in active use by the computer's CPU. CPU does not directly access these memories, instead they are accessed via input-output routines. Characteristics of Secondary Memory  These are magnetic and optical memories  It is known as backup memory.  It is non-volatile memory.  It is used for storage of the data in the computer.  Computer may run without secondary memory.  Slower than primary memories.  Normally have a high storage capacity. Example of optical memories are CDS (normally store up to 700 MB of data) and DVDs (normally store 4.7 GB for single layer DVDS and 8.5 GB for dual layer DVDs) and examples of magnet memories are Hard Disk Drives. 28  A hard disk also known as hard disk drive (HDD) is a non-volatile computer storage device containing magnetic disks or platters with high speed. It is a secondary storage device used to store data and program permanently Processing system unit The system unit is the case that contains electronic components of the computer used to process data. The size and layout of a system unit is called the form factor. Components of the system unit includes: the processor, memory, adaptor cards, ports, bays, and power supply The motherboard The motherboard (also known as the mainboard or logic board) is the primary circuit board in a computer that connects and allows communication between all the different components of the system. It serves as the central hub for connecting the CPU, memory, storage devices, and peripheral components Components of the motherboard Processor (Central Processing Unit) 29  The processor interprets and carries out the basic instructions that operate a computer. The processor significantly impacts the overall computing power and manages most computer operation. Central Processing Unit. The “brain” of the computer. Processors contains: Control unit Arithmetic Logic unit Registers. These three components work together to perform processing operations 1. The control unit: The control unit is the component of processor that directs and co-ordinates most of the operations in the computer. 2. a) Arithmetic Logic Unit: The Arithmetic Unit is another component of the processor, which performs arithmetic operations include basic calculations such as addition, subtraction, multiplication, and division. b) Logic operation unit: This performs comparison operations involving comparing one data item with another to determine whether the first item is greater than, equal to, or less than the other. Logical Operations. Include conditions along with logical operators such as AND, OR, and NOT. 3. Registers: Registers are temporary storage locations located inside the processor that are used to hold data, instructions or information waiting processing or output. Expansion slots These are connectors on a motherboard that allow additional hardware components or expansion cards to be installed into a computer system. An adaptor card sometimes called an expansion card is a circuit board that enhances functions of a component of the system unit and /or provides connections to peripheral. Ports and connections A computer port is a physical docking point using which an external device can be connected to the computer. Or A computer port is a physical or virtual interface through which a computer connects to peripheral devices or other systems. Ports facilitate the transfer of data between the computer and external devices or networks. Ports are slots on the motherboard into which a cable of external device is plugged in. 2 10  Following are few important types of ports: Serial Port Used for external modems and older computer mouse. Two versions: 9 pin, 25 pin model. Data travels at 115 kilobits per second. Parallel Port Used for scanners and printers Also called printer port. 25 pin model. 2 12  PS/2 Port Used for old computer keyboard and mouse Most of the old computers provide two PS/2 ports, each for mouse and keyboard. Universal Serial Bus (or USB) Port Can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc. Most of the computers provide two USB ports as minimum. Data travels at 12 megabits per second. USB compliant devices can get power from a USB port. VGA Port Connects monitor to a computer's video card. Has 15 holes. Three-pronged plug Connects to the computer's power cable that plugs into a power bar or wall socket. Firewire Port Transfer large amounts of data at very fast speed. Connects camcorders and video equipment’s to the computer Data travels at 400 to 800 megabits per second. Modem Connects a PC's modem to the telephone network. Ethernet Port Connects to a network and high speed Internet. This port resides on an Ethernet Card. Data travels at 10 megabits to 1000 megabits per second depending upon the network bandwidth. Game Port Connect a PC to a joystick. Now replaced by USB. Digital Video Interface, DVI port Connects a Flat panel LCD monitor to the computer's high-end video graphic cards. Very popular among video card manufacturers. 2 13  A sound card enhances the sound generating capabilities of a personal computer by allowing sound to be input through microphone and output through external speakers and headsets A serial port is a type of interface that connects a device to the system unit by transmitting 1 bit of data at a time. Serial ports usually connect devices that do not require faster data transmission e.g. monitor keyboard, or modem Parallel Port. A parallel port is an interface that connects devices by transferring more than 1 bit of data a time. Parallel ports were developed as an alternate to the slower speed serial ports. They connect devices such as printers. A USB hub is a device that plugs into a USB port on the system unit and contains multiple USB ports into which you plug cables from USB devices. 2 14