Input-Output device for college students bca

For input and output device

1. Components of Computer Dr. Mukta Sharma

2. Components of Computer Computer components can be broadly divided into two categories- Hardware and Software. Hardware refers to any physical component of a computer. For example, CPU, Monitor, Keyboard, Hard Disk, Floppy Disk, etc. Software refers to the programs which are required to operate the computer. For example, Operating Systems like DOS, Windows, Linux, Unix etc. Software languages such as BASIC, COBOL, dBase, Java, Python etc. and software like Accounting Software's, banking, Hospital, Hotel, Airlines etc.

3. Block Diagram of Computer A computer is a device that performs operations on raw data as per instructions given by the user. It can process data, pictures, sound, and graphics and can solve highly complicated problems quickly and accurately.

4. Block Diagram of Computer

5. The modern computer can be defined as an electronic machine that is designed to accept data and instruction store the data and instructions, process the data according to the instructions to produce desired results .  

6. Input Devices

7. Input Devices Tools for people to interact & communicate with computers . Enter data using input devices. Any hardware component that allows the user to enter data, programs, commands, and user response to a computer

8. Characteristics of good Input Timeliness Accuracy Usefulness

9. Input Devices Input devices are devices or instruments through which data and instructions are fed into the computer.

10. Keyboard A  keyboard  is the most common input device used in computer. By using a keyboard the user can type the text on the computer. User can also execute command by using keyboard. The number of keys on a typical keyboard varies from 82 to 108 keys.  

11. Keyboard Popularly keyboard are known as  QWERTY  keyboard. It is so as the starting letters of the keyboards are Q, W, E, R, T, Y  All the keys found on the keyboard falls in one of the following category: Digits Alphabets Special keys Symbols Arrow keys Function keys

12. Keyboard Keyboard is an input device consist of a set of typewriter- like keys that enable you to enter data into a computer. The keys on computer keyboards are often classified as follows: Alphanumeric keys – letters and numbers Modifier Keys - shift, ctrl, alt Function Keys - F1-F12 Cursor Movement Keys- arrow keys, PG Up/DN. Numeric Keypad- 0-9 +-*/ enter Special Purpose Keys- Esc, del, insert, printscrn, pause, scroll lock, start, shortcut.

13. The keyboard has four defined zones: Main Typing Area: Takes up the largest area of the keyboard, and includes the alphabet letters. It resembles a traditional typewriter. Numeric Keypad: Placed on the right part of the keyboard. Similar to a calculator keyboard. Edition keys: Located between the numeric keypad and the main typing area. It is very useful to move within texts and edit documents. Function Keys: Situated horizontally at the top of the keyboard. These keys are 'shortcuts' to perform specific tasks within different applications.

14. Main Keys Keys Function (mainly for texts) Enter It is used to execute a command, or to go to the following line in a text application. Backspace Goes back and erases characters to the left of the cursor Caps Lock Capital letters lock (it only affects the main typing area), light turns on to indicate upper case and off for lower case. Special Functions F1 These have specific functions, each application assigns them a different function. Page Up Scrolls the window contents by 'jumping' a full screen backwards. Page Down Scrolls the window contents by 'jumping' a full screen forward. Delete Erases characters to the right of the cursor. Num Lock Locks the numeric keypad: When light is on they act as numbers and when light is off they move, etc. Home & End Places the cursor at the beginning or end of a line. Insert Allows inserting words or letters within others. Esc Used by some applications to cancel processes. Shift Used to obtain upper cases and characters located in the upper part of keys. Alt Performs specific tasks when used in combination with other keys. Space bar Adds a space (moving the cursor to the right). Ctrl Performs specific tasks when used in combination with other keys.

15. Mouse Mouse   is a hand held input device. It is used to point any object on the screen. Mouse has rubber ball at lower side and buttons on top. Some mouse have two buttons whereas some has three. These buttons are used to enter command or information into the computer.   Mouse was invented by  Douglas Engelbart  in 1963 while working at Xerox PARC.

16. Mouse The mouse can perform following actions: Point : this means moving the mouse over a surface, like a table. This makes the pointer , a small arrow, move across the screen. This indicates our location on the screen. Click : this means pressing one of the mouse buttons and releasing it immediately. (It is important that the mouse doesn't move while you click) You can click either with the left or right buttons (Usually for shortcuts). (Some mice also have a middle button.) Double click: this means pressing the left (main) mouse button twice at a certain speed. Drag : this is clicking, holding the button down and moving or 'dragging' the mouse over the table or pad on which it is resting. Right Click: This is used for shortcut menu.

17. Types of Mice There are three types of mice : Mouse was introduced by Apple Macintosh in 1984 Mechanical : It has rubber or metal ball on its underside that can roll in all directions. Mechanical sensors within the mouse detect the direction of the ball is rolling and move the screen pointer accordingly. Opto mechanical: It is same as a mechanical mouse, but uses optical sensors to detect motion of the ball. Optical : It does a laser to detect the mouse’s movement. You must move the mouse along a special mat with a grid so that the optical mechanism has a frame of reference . Optical mice have no mechanical moving parts. They respond more quickly and precisely than mechanical and opto mechnical mice, but they are also more expensive.

18. There are various types of mouse : Mechanical mouse Opto -mechanical mouse Optical Mouse

19. Functions of a computer mouse Move the  pointing cursor  on the computer screen. Select  a particular file or folder. You can also select multiple file or folder at a time using mouse. By double clicking or by right clicking on a particular file or folder and then selecting 'Open' option we can  open the file or folder . Computer mouse can help us  drag and drop a file or folder . Computer mouse helps us  scroll the screen up and down . 

20. Joystick Joystick   is an input device. Joystick moves in all the direction and is used to control the movement of the cursor. Joystick provides controls like: Digital control Glide control Direct control

21. Joystick Joystick digital control helps movement in up, down, left and right directions only. The movement is thus limited in nature. Joystick glide control and direct control helps movement in all direction. It means 360º movement is possible.   Joysticks having direct control comes with added ability to respond to distance and speed.

22. Trackball Trackball   is an input device. It is a pointing device that contains a ball capable of rotating or moving in all directions. The user can move the cursor in desired direction by moving the ball in that particular direction. Mostly trackballs are used in Laptops.

23. Trackballs A trackball is like an upside down mouse. A mouse is moved over a pad. A trackball remains stationary, and the user moves the bal with his or her fingers or palm. One or more buttons for choosing options are incorporated into the design of the trackball.

24. Scanner Scanner  is an input device. Scanner is used to scan the image and then transform the scanned image into ASCII codes ad graphics.   To communicate with computer most scanners use utility program which helps them save the scanned image as graphic file on computer.   Most commonly used scanners are: Hand-held scanner Flat-bed scanner

25. Light Pen Light pen were developed for interactive graphics. It detects light pulses, rather than emitting light. Light Pen  is a hand-held electro-optical pointing device. When the light pen is brought closer to computer screen or touched on the screen then computer is able to determine where on the screen the pen is aimed at. Functions of Light Pen Important  functions of a light pen  is given below: Light pen is very useful in drawing images  Light pen is used for selecting objects on the display screen.

26. Touch Screen Touch Screen  is an input device which is sensitive to human touch . It allows the user to place the fingertip directly on the screen. It is a special display screen placed on computer monitor and allow direct selection of any object on the screen by directly touching with fingers.   Touch screen records the input when any object on the computer screen is touched with finger.   Touch screen devices are costly and are used in airlines, railway reservation counter, hospitals, etc.

27. Barcode Reader Barcode Reader  is a machine-readable code in form of a sequence of black and white vertical lines of different width and sizes. A barcode reader is used to read these codes and record the information. The recorded information in the bar code reader is shared by computer which is able to understand the information and recognize the meaning by reading thickness and spacing of the bars. A barcode reader can be hand held or fixed . It represents alphanumeric data by varying the width and combination of adjacent vertical lines. Used in various book stores, grocery stores, shopping mall

28. MICR Magnetic ink character reader helps in translating the information read into a coded format. This technology of reading information from the document by the means of magnetised ink characters which then is automatically recognized by the Magnetic ink document reader. Two std MICR fonts are:- E1313 Font- Used in USA & UA CMC7 Font- Originated in France & is used in Europe.

29. OCR Optical character recognition is a technique which allows the reading of printed characters or text documents. It is made up of minute spots. There are 2 std format used for OCR:- OCR-A: American Std OCR-B: European std.

30. OMR Optical Mark recognition is also called Mark sensing. It is an automatic optical sensing of marks recorded on the data medium.

31. Voice Input Device Voice recognition accepts the spoken words through a microphone and converts them into 0s and 1s.

32. Digitizer This converts graphic and pictorial data to digital (Binary format) There are two types of digitizer:- Flat Bed digitizer Image Scan digitizer

33. Output Devices Output can be in two forms Soft Copy Hard Copy

34. Monitor You will interact with your computer largely through its monitor or visual display unit. It works much like a television. The micro computer can use two basic types of monitor CRT LCD Now a days, Plasma, LED, etc. Monitor can be categorized by the way they display colors:- Monochrome Grayscale Colored Pixel. A single dot on the monitor screen. The name comes from "picture element." Multiple pixels are used to form characters and graphics.

35. Monitor Specification Monitor Size- It is 17 inch, 19 or 21 inch Monitor Resolution- Is classified by no. of pixels on the screen. (640*480 VGA),(800*600 SVGA),(1026*768 XGA) Refresh Rate-No. of times electron gun scan every pixel. Acceptable rate is 72 HZ or higher per second. Dot Pitch- All the 3 electrons should be together at a maximum distance of 0.28 millimeter for a crisp image.

36. Hard Copy Output Device Two hard copy output devices are: Plotters Printers.

37. Printers By far, paper is the single largest output you will have from your computer. Despite claims for "paperless" offices, it is still rare to not see printers outputting reams of paper. Printers can be classified as :- Impact Non-Impact

38. Criteria's for evaluating Printer Image quality- Also known as Print resolution measured in dpi. Speed- No. of pages per minute Initial cost Cost of Operation

39. Impact In this the print element does touch the paper, sometimes quite hard. Of course, it is named as impact. Examples are Dot Matrix Line Printer Daisy Wheel

40. Non-Impact One class is described as non-impact because the actual printing element never touches the paper. Example Inkjet Thermal Laser

41. Let's categorize some printers: Impact Non-Impact Dot Matrix Characters made up of dots Ink-jet Dots of ink make up characters Daisy Wheel Single character impacts Thermal Wires burn special paper Line Printer Prints entire line at a time Laser Full page printer

42. Impact Printers There are two impact printers: Dot matrix, Daisy wheel. The difference between the two is in the quality of the output. Dot matrix printers form characters from individual dots whereas a daisy wheel printer imprints fully-formed characters, much like a typewriter . The dot matrix is the more versatile of the two because of this the daisy wheel printer is not seen much any longer. Both printers impact the paper through a ribbon to transfer ink to the paper by the hitting element . Dot matrix printers use 9 to 24 individual wires.

43. Dot-matrix (impact) In a dot-matrix printer, a print head moves across the page . Characters or graphics are created by using a cluster of pins . These pins press an inked ribbon to the paper to create a dot . Each character or image is made out of a series of dots . These printers are usually cheap and durable , so they are still used by many businesses as invoice printers. They tend to be slow and noisy , and the output quality is the lowest of all types of printers.

44. Daisy wheel These printers work like a typewriter . Inside the printer is a wheel with a raised impression of each character in the alphabet and most common punctuation . To print a character, the wheel rotates , and an electronic hammer presses the character against an inked ribbon and the page. These printers tend to be slow and noisy , and changing fonts requires changing the wheel; however, their output can be better-quality.

45. Ink-jet The ink jet printer "shoots" individual dots of ink to the paper, calculating the location of each dot in order to form individual characters or dot graphics. When using these, a good paper is necessary to avoid smearing . These printers use ink-jet cartridges . Although you can print photos on plain-paper , you'll find that liquid inks tend to soak into the paper taking the color along with them. You'll get richer colors using coated papers that are less absorbent and designed specifically for photographs. The ink dries partly by absorption and partly by evaporation . If the paper is too absorbent, the image looks washed out.

46. Liquid Ink-jet Printers Liquid ink-jet printers propel fine droplets of liquid ink toward the surface of paper. In today's marketplace, this technology is the low-cost entry point for personal printing and low-volume color printing. A cartridge of ink is attached to a print head with up to hundreds of nozzles , each thinner than a human hair. The number of nozzles and the size of each determines the printer’s resolution. As the print head moves across the paper, a digital signal from the computer tells each nozzle when to propel a drop of ink onto the paper. On some printers, this is done with mechanical vibrations . Piezoelectric crystals change shape when a voltage is applied to them. As they do so, they force ink through the nozzles onto the paper. Each pixel in the image can be made up of a number of tiny drops of ink. The smaller the droplets , and the more of them, the richer and deeper the colors should be.

47. Material Inkjet printing, like conventional printing on a press, is binary. These printers can only put ink down. They can’t control the density of each dot . To achieve the illusion of continuous tones, the percentage of area covered by ink is modulated in one or both of two ways: A screening process maps the desired variations in density into variations in dot size. Thus, as the desired density increases , the dot sizes increase and a higher percentage of the white space is covered with ink. If the printing process supports smaller dots of a fixed size , area modulation is achieved by varying the number (rather than the size) of dots that are printed in any given small area. There are two pitches of concern with such printing: the dot pitch and the screen pitch. For example, an inkjet printer may have a raw dot pitch of 1200 dpi. An equivalent screen pitch may be defined as say, 75 dpi, where “dpi" refers to the equivalent dot per intch of a screen (lines per inch). Thus, each screen cell (75/inch x 75/inch) contains 1200/75 x 1200/75 = 64 raw dots. In such a case, each screen cell could be printed at any of 65 levels (0 to 64 dots). This process would then be equivalent to a 65 level, 75 pixel/inch printer.

48. Laser The laser printer is noted for producing a page of text at a time. In this printer a laser scans a photoactive plate building up an image of the printed page. Like in a Xerox machine, the plate is dusted with toner which sticks to the exposed areas. Paper is then placed in contact with the plate, transferring the image to the paper. A final heat bonding seals the toner to the paper. This all takes just a few seconds. Cyan, Magenta, Yellow, and Black color sticks are installed in the printer. Solid ink printers can print on nearly any kind of paper stock, an important feature if you make color proofs. For example; if you are a designer, you can simulate the appearance of a new design for your client by outputting the proof on the same stock as the final packaging. Solid ink printers work well with colored stock. These printers apply extremely vibrant and opaque color and are ideal for graphics.

49. Thermal Wax Printers Thermal-wax transfer was once the workhorse of print technologies, and can still be a very effective technology. Thermal-Wax printers are fast, deliver vibrant colors, are great for printing presentation graphics and the per-page cost is low. Quality Thermal-wax printing can produce vivid colors on a variety of office laser papers but the quality of continuous tone images does not approach that of dye-sub printers . Materials Instead of inks , thermal-wax printing uses a transfer roll or ribbon of colored wax that is segmented into page-sized sections each of the three subtractive colors (and optionally, black). The paper is a special paper but you can also use transparency film. Thermal Wax Transfer is one of the most widely used processes in scientific, technical, and business printing. https://youtu.be/Nd9Dgd0tVCU

50. Color Laser Printers Laser printers revolutionized black-and-white printing, making graphics and desktop publishing possible. However, color laser printers on the margins of photographic printing. Not only are their costs high, but their quality has not yet matched the very inexpensive ink-jet prin ters. The colors for laser printing are contained in four separate toner cartridges , one each for cyan, magenta, yellow and black . No special paper is required, but you can use different kinds to change the "look" of the print.

51. Impact vs Non-Impact Impact Printer Non Impact printer It prints characters or images by striking hammer or wheel against an inked ribbon It prints characters and images without striking the papers Its speed is slower Its speed is faster Its printing quality is lower Its printing quality is better It normally uses continuous paper sheet It normally uses individual paper sheet It generates noise during printing It does not generate noise during printing It uses inked ribbon for printing It uses toner or cartridge for printing It is less expensive It is more expensive Dot Matrix is an impact printer Laser Printer is a non impact printer

52. Plotters A plotter is a device that uses some mechanism to drive pens in defined horizontal/vertical motions in order to produce combined text and graphics figures. Most are driven by software that not only controls pen motion , but also pen color , with different colors available depending on the model purchased . Most personal computer plotters come with a flat bed . Other models are available with a pen that moves back and forth and wheels that drive the paper back and forth for the second dimension of motion. Finally , few plotters move the pen back and forth and roll a dr um with paper attached to obtain the other dimension.

53. Important Questions Define Printers along with there speed, dpi etc. Discuss input devices along with their characteristics Differentiate between Impact and Non-Impact printer. Describe few output devices.