GCSE ICT

1. GCSE ICT Input and Output Devices – Inputs Presented By Professor Ken Regis

2. Input devices • Input devices are used to get data into a system. • They should be able to do this as accurately and quickly as possible, and with the minimum of human intervention.

3. Input devices • The most common types of input devices are: • Keyboards • Point and Click devices (including mouse, tracker balls, touch sensitive pads, joysticks, light pens, touch screens, and graphic tablets)

4. Input devices • The most common types of input devices are: • Readers (including magnetic strip readers, barcode readers, optical character readers/recognition, magnetic ink character readers/recognition, and optical mark readers/recognition) • Punched cards and tape (including punched cards and Kimball tags)

5. Input devices • The most common types of input devices are: • Sound capture devices (including voice recognition and microphones) • Terminals (including EPOS and EFTPOS terminals)

6. Input devices • The most common types of input devices are: • Digital imaging devices (including video digitisers, scanners, digital cameras, and web cams) • Tonal devices (including touch tone telephones)

7. Keyboards • The most common type of keyboard is the QWERTY keyboard (so called because the top line of letters are q, w, e, r, t, and y.

8. Keyboards • Another type of keyboard is the concept keyboard. • The can be specially designed so that people with restricted vision can use them to interface with a computer. • Concept keyboards can also be programmed to perform common functions with one keystroke (e.g. a computerised till in a fast food restaurant).

9. Keyboard • Common input device • Standardised layout (QWERTY) (although non-alphanumeric keys are placed differently, and there is a difference between key assignments on UK and USA keyboards) QWERTY arrangement not optimal for typing - layout due to typewriters. Other keyboard designs allow faster typing but large social base of QWERTY typists produces reluctance to change. • Keypress closes connection, causing a character code to be sent • Usually connected by an umbilical cord • Allows rapid entry of text by experienced users

10. Keyboards cont

11. Other Keyboards Alphabetic Keys arranged in alphabetic order • not faster for trained typists • not faster for beginners either

12. Dvorak • common letters under dominant fingers • biased towards right hand • common combinations of letters alternate between hands • 10-15% improvement in speed and reduction in fatigue • But - large social base of QWERTY typists produce market pressures not to change

13. Chord keyboards • only a few keys - four or 5 • letters typed as combination of key presses • compact size - ideal for portable applications • short learning time – key preses reflect shape of desired letter • fast • But - social resistance, plus fatigue after extended use

14. Point and Click devices • Point and Click devices include mouse, tracker balls, touch sensitive pads, joysticks, light pens, touch screens, and graphic tablets.

15. TRACKERBALL • A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor. Large tracker balls are common on CAD workstations for easy precision. 

16. Trackball Bit like an upside-down mouse. Ball is rotated inside static housing, relative motion moves cursor. Indirect device, fairly accurate. Requires buttons for picking. Size and “feel” of trackball itself important. Requires little space, becoming popular for portable and notebook computers.

17. Tracker ball • The tracker ball is essentially an upside down mouse. • Instead of moving the mouse on the table top, the ball is rotated. • This achieves the same result as using a mouse but takes up far less room.

18. Mouse • The mouse translates movement on the desktop into digital information. • This is information is converted into movement of the cursor on the screen. • A mouse will also have one, two, or three buttons which can be clicked to help the user to select what functions they wish to use.

19. Mouse cont Mouse located on desktop • requires physical space • no arm fatigue Relative movement only is detectable. Movement of mouse moves screen cursor Screen cursor oriented in (x, y) plane,mouse movement in (x, z) plane: an indirect manipulation device. Device itself doesn’t obscure screen, is accurate and fast. Can lead to hand-eye coordination problems due to indirectness of manipulation.

20. How does it work? Two methods for detecting motion Mechanical Ball on underside of mouse turns as mouse is moved Rotates orthogonal potentiometers Can be used on almost any flat surface

21. Optical Mouse light emitting diode on underside of mouse sits on special grid-like pad on desk; less susceptible to dust and dirt detects fluctuating alterations in reflected intensity as mouse is moved over the gridlines, used to calculate relative motion in (x, z) plane Also a device known as the foot mouse - operated with the feet; a rare device, not in common use

22. Touch sensitive pad • These are most commonly found on laptop computers. • A stylus or the user’s finger is pressed gently onto the pad, and as it is moved the cursor moves on the screen.

23. Joystick • These are most commonly used to interact with computer games, although they are also used in other circumstances (e.g. on hospital scanners). • Like the tracker ball, the movement of the joystick moves the cursor on the screen,

24. Joystick Indirect device Takes up very little space Controlled by either • movement (absolute joystick) - position of joystickcorresponds to position of cursor • pressure (isometric or velocity-controlled joystick) - pressure on stick corresponds to velocity of cursor Usually provided with buttons (either on top or on front like a trigger) for selection Does not obscure screen Inexpensive (often used for computer games, also because they are more familiar to users)

25. Light pen • Light pens are usually used with specialist design software. • The light pen works by being touched against the screen. • As the pen is moved on the screen, the cursor moves.

26. Light pen Coiled cable connects pen to c.r.t. In operation, pen held to screen and detects burst of light from screen phosphor during display scan. Direct pointing device: accurate (can address individual pixels), so can be used for fine selection and drawing. Problems: pen can obscure display, is fragile, can be lost on a busy desk, tiring on the arm. Both much less popular than the mouse

27. Touch screen • The touch screen is a special type of screen which is sensitive to touch. • Selections can be made by touching the screen. • These are particularly useful in banks, building societies, and shops, where customers who are not used to using a keyboard can interact with a computer system.

28. Touch screen

29. Touch-sensitive screen (touch screens) Detect the presence of finger or stylus on the screen. Work by interrupting matrix of light beams or by capacitance changes or ultrasonic reflections. Direct pointing devices. Advantages: Fast, and require no specialized pointer. Good for menu selection. Suitable for use in hostile environment: clean and safe from damage. Disadvantages: Finger can mark screen. Imprecise (finger is a fairly blunt instrument!) - difficult to select small regions or perform accurate drawing. Lifting arm can be tiring, and can make screen too close for easy viewing.

30. Graphics tablet • A graphics tablet allows the user to create designs directly onto the screen. • A special stylus is connected to the computer via the graphics tablet, and as the user ‘draws’ on the tablet with the stylus the drawing appears on screen.

31. Handwriting recognition Handwritten text can be input into the computer, using a pen and a digesting tablet • common form of interaction Problems in • capturing all useful information - stroke path, pressure, etc. in a natural manner • segmenting joined up writing into individual letters • interpreting individual letters • coping with different styles of handwriting Handheld organizers being released now that incorporate handwriting recognition technology and do away with a bulky keyboard

32. Handwriting recognition

33. Readers • The most common types of reader used include magnetic strip readers, barcode readers, optical character readers/recognition, magnetic ink character readers/recognition, and optical mark readers/recognition).

34. Magnetic strip readers • The most common magnetic tape readers are those used at electronic points of sale (EPOS). • These ‘read’ the personal data stored on the magnetic strip of a credit or debit card.

35. Barcode readers • Barcodes are used in shops, libraries, luggage handling, and stock control. • The lines on a barcode represent numbers, and can be scanned very quickly using a laser scanner.

36. Optical character readers/recognition • Optical character recognition is a method of inputting text using a scanner. • It requires special software to convert the scanned image of each letter into an ASCII (American Standard Code for Information Interchange) code, and it often confuses similar shaped letters and numbers (e.g. S and 5, B and 8).

37. Magnetic ink character readers/recognition • Magnetic ink characters are printed at the bottom of cheques. • They are used by banks to identify the bank a customer banks with, the individual branch where their account is held, and the customer’s bank account number.

38. Magnetic ink character readers/recognition Cheque number Branch code Account number

39. Optical mark readers/recognition • Optical mark recognition sense marks made on specially designed forms (e.g. multiple choice answer sheets, lottery cards). • OMR is a very cheap, easy and quick to handle system of inputting data, but if a user makes a mistake they are difficult to correct.

40. Optical mark readers/recognition

41. Punched cards and tape • Punched cards and tape were used by the first computers to store programs and data. • They are seldom used today except for clock cards, which records when a person starts and ends work, and Kimball tags, which are used for stock control.

42. Sound capture devices • The most common use of sound capture devices involves the use of voice recognition software and microphones.

43. Sound capture devices • Voice recognition software ‘remembers’ the way a user speaks, and converts their speech into text that appears on screen. • Although voice recognition software has become increasingly sophisticated, many such programs have difficulty converting more than 90% of common words accurately.

44. Terminals • EPOS (Electronic Point Of Sale) and EFTPOS (Electronic Fund Transfer at Point Of Sale) terminals are connected, via secure Internet connections, to the computers of the main banks and credit card companies.

45. Terminals • EPOS and EFTPOS allow a retailer to transfer the cost of what they have sold to a customer from the customer’s credit card or bank account to their own bank account. • This is much faster than accepting payment by cheque, and more secure than accepting payment in cash.

46. Terminals • It also gives the retailer an opportunity to collect information about their customers, and to develop individual customer profiles (i.e. know what an individual customer may want to buy). • This helps to retailer to ‘target’ individual customers with special offers etc.

47. EPOS & EFTPOS

48. Digital imaging devices • These include video digitisers, scanners, digital cameras, and web cams.

49. Video Digitisers • The video digitiser is a combination of hardware and dedicated software that converts an analogue signal into a digital signal. • This is the basis of most set top boxes that give access to digital television on standard television sets. • It can also be used to ‘capture’ still images from video.

50. Scanners • Scanners are used to scan text or images so that they can be stored on and manipulated by computer. • The scanner converts the text or image into a digital signal which it sends to the computer. • The user can then decide whether they want to store or manipulate what they have scanned.