Computer fundamentals Computer fundamentals Input Out put Devices

Computer fundamentals Computer fundamentals Input- Out put Devices Afroza Nahar

Illustrating the role I/O devices in a computer system Computer fundamentals Computer fundamentals • A computer system can be useful, only when it is able to communicate with its external environment (its users). • As shown in the following figure, the input –output devices provides the means of communication between the computer and the outer world. They are also known as peripheral devices, because they surround the CPU and the memory of a computer system. Input Data from external world 1/3/2022 Input Device Input Data coded internal form CPU And Memory Afroza Nahar Processed Data in internal form Output Device Result of Processing In human Acceptable form 2

What Is Input? Computer fundamentals Computer fundamentals Ø Data or instructions entered into memory of computer Ø Input device is any hardware component used to enter data or instructions 1/3/2022 Afroza Nahar 3

Input Devices Computer fundamentals Computer fundamentals 1/3/2022 Page 90 Afroza Nahar 4

What is input? Computer fundamentals Computer fundamentals • What are the two types of input? Ø Data Ø Unprocessed text, numbers, images, audio, and video Ø 1/3/2022 Instructions • Programs • Commands • User responses Afroza Nahar 5

Input Devices Computer fundamentals Computer fundamentals • An input device is an electromechanical device, which accepts data from the outside world, and transferring them into a form, which computer can interpret. • Several input devices are available today. • They can broadly classified into the following categories: – Keyboard Device – Point-and-draw Device – Data scanning devices – Digitizer 1/3/2022 Afroza Nahar • Electronic cards based Device • Voice recording Device • Vision based devices 6

Input Devices Computer fundamentals Computer fundamentals • Keyboard device : – Keyboard device are the most commonly used input device today. – They allow the data entry into a computer system by pressing a set of keys (labeled buttons) 1/3/2022 – They are nearly mounted on a keyboard, which is connected to the computer system. – The most popular keyboard used today is the 101 -keys QWERTY keyboard 1/3/2022 Afroza Nahar 7

Computer fundamentals Computer fundamentals • How is the keyboard divided? Ø Ø Ø 1/3/2022 Typing area Numeric keypad Function keys, special keys that issue commands Afroza Nahar 8

What are alternative forms for commands? Computer fundamentals Computer fundamentals Ø Many programs allow you to use key combination, menu, or button to obtain same result MICROSOFT WORD KEY COMBINATION EQUIVALENTS Key Combination Menu | Command Copy Shift+F 2 or Ctrl+C Edit | Copy Open Ctrl+F 12 File | Open Paste Ctrl+V Edit | Paste Command 1/3/2022 Button 9

Input Devices Computer fundamentals Computer fundamentals • Point-and-Draw Devices : – Point-and-draw devices are input devices, which can be used to rapidly point to and select a particular graphic icon or menu item from the multiple options displayed on the screen. – Many of this devices can also be very effectively used to create graphic eliminates on the screen, such a s lines, curves, and freehand shape. – Some of the commonly used point-and Draw devices are » Mouse » Trackball » Joystick » Electronic pen » Touch screen. 1/3/2022 Afroza Nahar 10

Point-and-Draw Devices Computer fundamentals Computer fundamentals • Mouse: • Mouse is the most popular point-and-draw device. • It has became a must-have input device on personal computers and workstations, which have a GUI-based user interface. 1/3/2022 Afroza Nahar 11

Pointing Devices Computer fundamentals Computer fundamentals mouse buttons wheel button ball mouse pad 1/3/2022 Afroza Nahar 12

What is an optical mouse? Computer fundamentals Computer fundamentals Ø No moving mechanical parts inside Ø Senses light to detect mouse’s movement Ø More precise than mechanical mouse Ø Connects using a cable, or wireless 1/3/2022 Afroza Nahar 13

What are common mouse operations? Computer fundamentals Computer fundamentals Point 1/3/2022 Click Doubleclick Drag Rightdrag Rotate wheel Press wheel button Tripleclick Rightclick 14

Trackball Computer fundamentals Computer fundamentals • A trackball is pointing device, which is similar to a mouse. As shown in the following figure. • The ball which is placed in the base of a mouse, is placed on the top along with buttons, in case of a trackball. • To move the graphics cursor around the screen, the ball is rolled with the fingers. 1/3/2022 Afroza Nahar 15

Trackball Computer fundamentals Computer fundamentals • Because the whole device is not moved for moving the graphics cursors, a trackball requires less space than a mouse for operation. • Since it need not be moved for moving the graphics cursors, it is often attached to or built into the keyboard. • Trackballs built into the keyboard are commonly used in laptop computers, because a mouse is not practical for laptop users in a small space. 1/3/2022 Afroza Nahar 16

Joystick Computer fundamentals Computer fundamentals • A joystick is a pointing device, which works on the same principle as a trackball. • To make the movement of the spherical ball easier, the spherical ball, which moves in a socket, has a stick mounted on it (see the following figures) 1/3/2022 Afroza Nahar 17

What is a wheel? Computer fundamentals Computer fundamentals – Wheel is steering-wheel-type input device • Pedal simulates car brakes and accelerator 1/3/2022 Afroza Nahar 18

Electronic Pen Computer fundamentals Computer fundamentals – Handheld input device that can detect light • Press light pen against screen surface and then press button on pen 1/3/2022 Afroza Nahar 19

Touch Screen Computer fundamentals Computer fundamentals • Touch screen is the most simple, intuitive, and easiest to learn of all input devices. • A Touch screen enables the users to choose from available options by simply touching with their fingers the desired icon or menu item displayed on the computer’s screen. • Touch screen are the most preferred human-computer interface devices used in information kiosks. 1/3/2022 Afroza Nahar 20

Touch Screen (cont…) Computer fundamentals Computer fundamentals • An information kiosks is an unattended system, which is used to store information of public interest, and allows common people to access the stored information as per their requirement, For example, information kiosks may located • At an airport or a railway station to provided information to arriving passengers about hotels, restaurants, tourists spots, etc. in the city. • In large museums or zoos to guide the visitors to the locations of various attractions and facilities, and to caution them against things, which they are not supposed to do while inside. 1/3/2022 Afroza Nahar 21

What is a touch screen? Computer fundamentals Computer fundamentals Ø Touch areas of screen with finger Ø Often used with kiosks 1/3/2022 Afroza Nahar 22

Input Devices Computer fundamentals Computer fundamentals • Data Scanning Devices • Optical Character Recognition (OCR ) Device • Optical Mark Reader (OMR) • Bar-Code Reader • Magnetic-Ink Character recognition (MICR) • Digitizer • Electronic-card Reader • Voice Recognition Devices 1/3/2022 Afroza Nahar 23

Voice Input Computer fundamentals Computer fundamentals Step 1. A user dictates text into a microphone. Step 2. An analog-to-digital converter (ADC) translates sound waves into digital measurements computer can process. Measurements include pitch, volume, silences, and phonemes. Phonemes are sound units such as aw and guh. 1001011101011000011 01 Step 4. To narrow a list down, software presents user with a list of choices or uses a natural language component to predict most likely match. User may correct any selection made by software. Natural Language Engine 1/3/2022 Step 3. Software compares spoken measurements with those in its database to find a match or list of possible matches. Matches 24

What is a MIDI (musical instrument digital interface)? Computer fundamentals Computer fundamentals Ø 1/3/2022 External device, such as electronic piano keyboard, to input music and sound effects Afroza Nahar 25

Output Devices Computer fundamentals Computer fundamentals • The various types of output devices along with their typical application ØMonitor ØPrinters ØPlotters ØScreen image projector ØVoice response system 1/3/2022 Afroza Nahar 26

What is a printer? Computer fundamentals Computer fundamentals portrait v Output device that produces text and graphics on paper v Result is hard copy, or printout v Two orientations: portrait and landscape 1/3/2022 Afroza Nahar 27

How does an ink jet printer work? Computer fundamentals Computer fundamentals • Nozzle-like print head that sprays ink onto paper to form characters and graphics • Most ink jet printers use CMYK color 1/3/2022 Afroza Nahar 28

How do laser printers compare to ink jet printers? Computer fundamentals Computer fundamentals • A laser printer paints dots of light on a light-sensitive drum – Higher quality than ink jet – More expensive to buy than ink jet – Less expensive to operate than ink jet 1/3/2022 Afroza Nahar 29

How do laser printers compare to ink jet printers? Computer fundamentals Computer fundamentals 1/3/2022 Afroza Nahar 30

What is a dot matrix printer? Computer fundamentals Computer fundamentals • Produce characters and graphics by using a grid of fine wires – Introduced in 1970 s – Low quality output – Used for “back-office” applications that demand low operating cost and dependability – Can print multipart carbon forms 1/3/2022 Afroza Nahar 31

What is a dot matrix printer? Computer fundamentals Computer fundamentals 1/3/2022 Afroza Nahar 32

Dot matrix printer Computer fundamentals Computer fundamentals 1/3/2022 Afroza Nahar 33

Computer fundamentals Computer fundamentals 1/3/2022 Afroza Nahar 34

How do you know which printer to buy? Computer fundamentals Computer fundamentals – Depends on printing needs Speed Budget Cost per page Graphics capability System compatibility 1/3/2022 Color or black and white Photo printing Future needs Afroza Nahar Paper types and sizes Wireless capability 35

What other printer technologies are available? Computer fundamentals Computer fundamentals • Thermal transfer printer – Uses page-sized ribbons coated with wax – Print head consists of heating elements to melt the wax • Dye sublimation printer – Similar to wax, but page-sized ribbon contains dye – Print heads diffuse the dye 1/3/2022 Afroza Nahar 36

Printers: What features should I look for in a printer? Computer fundamentals Computer fundamentals • Resolution – Measured in dpi (dots per inch) • Print speed – Measured either by pages per minute (ppm) or characters per second (cps) • Color takes longer than black and white • Text prints faster than graphics 1/3/2022 Afroza Nahar 37

What features should I look for in a printer? Computer fundamentals Computer fundamentals • Duty cycle - indication of the number of pages a printer can be expected to print per month • Indicates maintenance costs • Operating costs – Printers require ongoing costs including ribbons, ink cartridges, and toner – Per copy cost is the cost of printing a page with an average amount of text, graphics, and color 1/3/2022 Afroza Nahar 38

What features should I look for in a printer? Computer fundamentals Computer fundamentals • Duplex capability – A printer with duplex capability can print on both sides of the paper • Memory – A computer sends data for a printout to the printer along with a set of instructions on how to print the data 1/3/2022 Afroza Nahar 39

Installing Peripheral Devices: Is it difficult to install a new peripheral device? Computer fundamentals Computer fundamentals • Internal devices – Tools required • Screwdriver • Directions – Before installing • Unplug the computer • Ground yourself – Installing • Follow the directions 1/3/2022 Afroza Nahar 40

What’s an expansion slot? Computer fundamentals Computer fundamentals • Expansion slot - long, narrow socket on the system board into which you can plug an expansion card • Expansion card - small circuit board that provides computer with ability to control storage, input or output device 1/3/2022 Afroza Nahar 41

What’s an expansion slot? Computer fundamentals Computer fundamentals • ISA (Industry Standard Architecture) – Used today only for some modems and other relatively slow devices • PCI (Peripheral Component Interconnect) – Offers fast transfer speeds and a 32 -bit or 64 -bit data bus • AGP (Accelerated Graphics Port) – Provides a high-speed data pathway primarily used for graphics cards 1/3/2022 Afroza Nahar 42

Do notebook computers contain expansion slots? Computer fundamentals Computer fundamentals • Equipped with a special type of external slot called a PCMCIA slot • Typically a notebook only has one slot, but the slot can hold more than one PC card (PCMCIA expansion cards) 1/3/2022 Afroza Nahar 43

What is an expansion port? Computer fundamentals Computer fundamentals • Used to connect a peripheral device • Expansion port - any connector that passes data in and out of a computer or peripheral device 1/3/2022 Afroza Nahar 44

What is a digital camera? Computer fundamentals Computer fundamentals Ø Allows you to take digital pictures Ø Images viewable immediately on camera • Download to computer • Post pictures to Web 1/3/2022 Afroza Nahar 45

How does a digital camera work? Computer fundamentals Computer fundamentals Step 3. CCD generates an analog Step 1. Point to the image to photograph and take picture. Light passes into the lens of the camera. Step 2. Image is focused on a chip called a charge-coupled device (CCD). signal that represents the image. Step 4. Analog signal is converted to digital signal by analog-todigital converter (ADC). Step 5. Digital signal processor (DSP) adjusts quality of image and usually stores digital image on miniature mobile storage media in the camera. Step 6. Images are transferred to a Step 7. Using software computer’s hard disk by plugging one end of the cable into a camera and the other end into a computer; or images are copied to hard disk from storage media used in the camera. supplied with the camera, images are viewed on screen, incorporated into documents, edited, and printed. 1/3/2022 Afroza Nahar 46

What is resolution? Computer fundamentals Computer fundamentals Ø Sharpness and clarity of image Ø The higher the resolution, the better the image quality, but the more expensive the camera Ø Pixel (picture element) is single point in electronic image Ø Greater the number of pixels, the better the image quality 1/3/2022 Afroza Nahar 47