94678

INPUT DEVICES

Конспект урока

Иностранные языки, филология и лингвистика

A mouse is a device for controlling the cursor and selecting items on the screen. Typically, a mouse is a palm-sized device, slightly smaller than a pack of cards. On top of the mouse there are one or more buttons for communicating with the computer.

Английский

2015-09-15

141.5 KB

2 чел.

41

UNIT III

INPUT DEVICES

INTRODUCTORY TEXT

                       

                                  Input devices are the pieces of hardware

                                  which allow us to enter information into the computer. The most common are the keyboard and the mouse.

The keyboard allows the user to key in programs and data and to control the computer system. There are keyboards with different number of keys nowadays.

A mouse is a device for controlling the cursor and selecting items on the screen. Typically, a mouse is a palm-sized device, slightly smaller than a pack of cards. On top of the mouse there are one or more buttons for communicating with the computer. A ‘tail’ or wire extends from the mouse to a connection on the back of the computer.

Besides the mouse there are other cursor control devices. They are a trackball and a joystick.

A trackball is similar to a mouse but it has the ball on top. To move the cursor on the screen, the user rotates the ball using his fingers.

To operate a joystick, the user grips and moves a vertical lever. The movement of the lever causes the cursor to move around the screen. Pressing a button on the joystick puts the required process into operation. Cursor movements can be made very quickly using this device therefore it is often used for playing fast action games.

We can also interact with the computer by using many other specialized input devices: a scanner, a lightpen, a graphics tablet, or a voice recognition device.

A scanner converts text or pictures into electronic codes that can be manipulated by the computer.

Lightpens and graphics tablets are referred to drawing devices used for CAD (Computer-Aided Design).

A lightpen is similar in shape to an ordinary pen. It is held against the screen and works by sending signals to the computer when it senses the light given off by the screen. This enables the computer to calculate its position. As the light pen is moved, lines appear on the screen. The special programs used with the light pen allows the lines to be increased or decreased in size or moved to different positions.

A graphics tablet has a flat board (or tablet) across which a pen is moved. By using the reflection of light, ultrasound or other methods the graphics tablet can measure the distance of the pen from the sides of the tablet and therefore calculate its position. As the pen is moved across the tablet lines are displayed on the screen.

A voice recognition device allows the user to input data by speaking into a microphone. The computer compares the input with the sound patterns of words stored in the memory.  To reduce the amount of memory required, the vocabulary used with this device is limited to a few words. However, the large amount of memory needed to analyse the input makes it difficult to use this device with microcomputer.

TOPICAL VOCABULARY

  1.    key in                          вводить с клавиатуры
  2.    wire                             провод, проводник, шина
  3.    extend                         расширять, наращивать, увеличивать,

                                            делать длиннее

  1.    rotate                          поворачивать, вращать(ся)
  2.    grip                             схватить, сжать, крепко держать
  3.    lever                            рычаг
  4.    lightpen                      световое перо
  5.    graphics tablet            графический планшет (syn. digitizing

                                            tablet)

  1.    refer to                        ссылаться на, относить к, приписывать
  2.  flat                              плоский, ровный
  3.  pattern                        образец, модель, шаблон
  4.  reduce                         уменьшать, снижать

EXERCISES

  1.  After reading the text give a short description of each input device mentioned above according to the following plan:
  •  The name
  •  Its look
  •  Its usage

Do you know any other input devices?

Can you describe them according to the same plan?

  1.  Decide which of the input device would best suit each of these requirements. In some cases more than one variant is possible.
  •  To input mathematical information.
  •  To copy engineering drawings.
  •  To guide a rocket in a computer game.
  •  To help a busy manager to find a file quickly.
  •  To help disabled people who cannot move their arms.
  •  To design new components without first making a large number of drawings.
  •  To help young children learn to spell.

  1.  Read some additional information about the keyboard, mouse and scanner.

Keyboard

Any keyboard has the following groups of keys:

  •  alphanumeric keys: arranged in the same order as  a typewriter ( this layout is known as QWERTY because these are the first six letters on the top left of the keyboard);
  •  function keys: used by various programs to instruct the PC to perform specific tasks, such as Save, Copy, Cut, Paste, Help, etc;
  •  numeric keypad: set of numeric or editing keys (the Num Lock key is used to switch from numbers to editing functions);
  •  editing keys: cursor and other keys usually used within word processors to page up and down in a long document or to edit  text (using Insert or Delete keys);
  •  special keys: used to issue commands or to produce alternative characters in key combinations, for example, the Alt key.

Most keys of the keyboard are auto-repeating, that means that , if they are held down, they repeat their function again and again until they are released.

Mouse

The mouse is designed to slide around on your desktop. As it moves, it moves an image on the screen called a pointer or mouse cursor. The pointer usually looks like an arrow or I-bar, and it mimics the movements of the mouse on your desktop.

What makes the mouse especially useful is that it is a very quick way to move around on a screen. The mouse also issues instructions to the computer very quickly. Point to an available option with the cursor, click on the mouse, and the option has been chosen.  

Mice are so widely used in graphic applications because they can do things that are difficult, if not impossible, to do with keyboard keys. For example, the way you move an image with a mouse is to put the pointer on the object you want to move, press the button and drag the image from one place on the screen to another. When you have the image where you want it, you release the button and the image stays there. Similarly, the mouse is used to grab one corner of the image (say a square) and to stretch it into another shape (say a rectangle).

The buttons on the mouse are used to select items at which the mouse points. You position the pointer on an object on the screen, for example, on a menu or a tool in a paint program, and then you press the mouse button to ‘select’ it. Mice are also used to load documents into a program: you put the pointer on the file name and double-click on the name – that is, you press a mouse button twice in rapid succession.

Scanner

In a flatbed scanner, the paper with the image is placed face down on a glass screen similar to a photocopier. Beneath the glass are the lighting and measurement devices. Once the scanner is activated, it reads the images as  a series of dots and then generates a digitized image that is sent to the computer and stored as a file. The manufacturer usually includes software which offers different ways of treating the scanned image.

A colour scanner operates by using three rotating lamps, each of which has a different coloured filter: red, green and blue. The resulting three separate images are combined into one by appropriate software.

  •  Write English equivalents for the following:

расположение; набор чего-л.; переключаться с …на …; редактировать текст; давать распоряжение; автоповтор; удерживать; имитировать; указатель; щелкать; тащить; отпускать; подобно; захватывать что-л.; в быстрой манере; лицом вниз; под чем-л.; серия чего-л.; вращающаяся лампа.

  •  Choose one of the above mentioned input devices and speak about it in details.

  1.  Match these descriptions with the words from the box.

scanner 

  1.  Short for Alternate key, it is like a second Control key. It is standard on all PCs. You use it in the same fashion as the Control key - holding it down while you press another key. The meaning of any this key combination depends on which application is running.

On Macintoshes, the equivalent key is called the Option key.

  1.  Most computer keyboards contain four such keys for moving the cursor or insertion point right, left, up, or down. When combined with the Shift, Function, Control, or Alt keys (on PCs), these keys can have different meanings. The exact manner in which these keys function depends on which program is running. Some programs ignore them.

  1.  A feature of some keys on computer keyboards that causes them to repeat as long as they are held down.

  1.  An 84-key keyboard introduced with the PC /AT. It was later replaced with the 101-key keyboard which is called …

  1.  A key that moves the cursor or insertion point backward one character space. In addition to moving the cursor backward, this key usually deletes the character to the left of the cursor or insertion point. It is particularly useful, therefore, for correcting typos.
  2.  A key on computer keyboards that turns insert mode on and off. This key does not work for all programs, but most word processors and text editors support it.

  1.  Special keys on the keyboard that have different meanings depending on which program is running. These keys are normally labeled F1 to F10 or F12 (or F15 on Macintoshes). New PCs have the enhanced keyboard, with twelve these keys aligned along the top of the keyboard.

  1.  A keyboard for Macintosh computers that contains up to 15 function keys above the alphanumeric keys, and a numeric keypad. It is sometimes called an enhanced keyboard because of its similarity to the PC enhanced keyboard.

  1.  A key that moves the cursor (or insertion point) to the beginning of the next line, or returns control to whatever program is currently running. After a program requests information from you (by displaying a prompt), it will usually not respond to your input until you have pressed this key. This allows you to correct typing mistakes or to reconsider your entry before it is too late.

  1.  A special cursor control key on PC keyboards and Macintosh extended keyboards. This key has different meanings depending on which program is running. For example, it might move the cursor to the end of the line, the end of the page, or the end of the file.

  1.  This key is used to remove characters and other objects. On PCs, this key generally removes the character immediately under the cursor (or to the right of the insertion point), or the highlighted text or object. It deletes the character under the cursor, and the Backspace key deletes the character to the left of the cursor or insertion point.

  1.  This key is a special code that moves the cursor (or print head) to the beginning of the current line. In the ASCII character set, it has a decimal value of 13.

  1.  A toggle key on computer keyboards that, when activated, causes all subsequent alphabetic characters to be uppercase, but has no effect on other keys.

  1.  The pressing of a key. The efficiency of software programs is sometimes measured by the number of key pressings it requires to perform a specific function. The fewer the key pressings, claim some software producers, the faster and more efficient the program.

LISTENING SKILLS

                                                               

  •  Listen to the description of three input devices. What are they?

                                                                                                              

  1.  …………
  2.  …………
  3.  …………

  •  Listen to the conversation between Vicky Cameron, an Information Technology (IT) lecturer, and complete these notes.
  1.  The technology used in scanners is similar to that used in ……………………………………………………………………………..
  2.  A laser beam reads the image in ………………………………
  3.  The image is then ……………………………………………...
  4.  Text is scanned with…………………………………………...
  5.  Black-and-white scanners work best with …………………….
  6.  Greyscale scanners have been designed to work with ………...
  7.  Colour scanners produce lovely images on screen but ………..

 DISCUSSION

                                                         Working in pairs make up dialogues

                               discussing the following problems.

  1.  You friend knows little about  the computer. He asks you questions keys of the keyboard. Tell him all you know.
  2.  One of you is a manager in a shop selling computers. Tell your customer how to use the mouse.
  3.  One of you is a teacher. Your student was given the task to learn about input devices. Ask him for this information.

SUPPLEMENTARY READING

                                           KEYBOARD LAYOUT

                                  Long existing standards dictate the location of most

                           of the keys, such as the numbers, letters, symbol keys and the standard function keys, such as shift, new line and backspace. These keys are in the "touch" area and account for most of the keystrokes the user makes without breaking rhythm and losing speed. Special function keys, such as CLEAR are in nontouch locations and can be struck only if the user moves the hand away from the home position. They are in the nontouch area because they are infrequently used and should be viewed for verification before being struck.

The QWERTY layout is currently the most popular keyboard configuration. It is named after the first six keys of the upper left hand row. It was developed in 1872 and laid out to slow typists down somewhat and so prevent "jamming" of mechanical typewriters. The DVORAK layout was proposed in 1932 as a faster and more efficient layout (Dvorak, 1943). This layout places the most frequently used keys on the home row. While it can be shown to be an improvement over the QWERTY layout, the magnitude of the advantages have not been shown sufficient to justify retrofitting keyboards and retraining typists. Thus, it currently has limited acceptance.

KEY MECHANISM

Efficient keying requires that keys function with minimum adequate force and with sufficient displacement to provide muscular feedback to the user. Key forces for current high production keyboards are in the range of 0.40 to 1.25 newtons with key displacements of 3 to 5 mm. Key spacing, key travel, force and key feedback are keyboard characteristics generally agreed on by most manufacturers and are specified by ANSI as follows:

"Center line distances between adjacent keys shall be between 18 and 19 mm (0.71 and 0.75 inch) horizontally, and between 18 and 21 mm (0.71 and 0.82 inch) vertically (Clare, 1970). 

"The keys...shall have a maximum vertical displacement between 1.5 and 6.0 mm (0.06 and 0.24 inch). 

"The preferred displacement is between 2.0 and 4.0 mm (0.08 and 0.16 inch). 

"The maximum force to depress the keys, expressed in Newtons (N)...shall range between 0.25 N and 1.5 N. The preferred key force is between 0.5 N and 0.6 N." 

The more proficient the user, the lighter the touch can be. If too little force is required, however, extra keys may be struck accidentally, and if too much force or displacement is required, some keys may fail to be actuated because the user did not press hard enough. Also, excessive force induces finger fatigue. There is evidence (Kinkead and Gonzales, 1969; Alden, Daniels and Kanarick, 1972) that optimum force/displacement characteristics of a key require a steadily increasing force as the key is depressed until contact is made. Immediately beyond that point, the force is sharply changed so that users can easily "feel" when the key has been pressed sufficiently. A typical force displacement curve for a key with tactile feedback is shown in.

FINAL TEST

                                      

                                        

  •  Choose the sentences which are true to the information of the introductory text (Выберете предложения, соответствующие информации вводного текста)

1.  A. The keyboard and the mouse are the only available input devices.

  1.  A trackball looks like a mouse and the difference is that it has a ball on its top.

    C. Lightpens and joysticks are referred to drawing devices used for CAD (Computer-Aided Design).

      D. A voice recognition device needs a lot of memory.

         E. A graphics tablet like a lightpen is useful for making drawings with the help of the computer.

  •  The main idea of the text about the keyboard (exercise 3) can be expressed as: (Главная идея текста о клавиатуре может быть выражена как:)

2. A. All keyboards have the same amount of keys.

  1.  The description of the most useful keys found on any keyboard.
  2.  Functional keys are the main keys of any keyboard.

 

  •  The main idea of the text about the mouse (exercise 3) can be expressed as:

3. A. To show that the mouse is more functional than the keyboard.

   B. To show what the mouse can do as an input device.

  1.  To show the construction of the mouse and the main fields of its usage.
  •  The main idea of the text about the scanner (exercise 3) can be expressed as:

4. A. To describe the difference between a flatbed and  colour  scanner.

   B. To describe the operating  mechanism of a flatbed and  colour  scanner.

   C. To stress the difference between a flatbed and  colour  scanner.

  •  Give the right English equivalent to the following Russian sentence (Дайте верный английский эквивалент русскому предложению)

Как утверждают некоторые производители программного обеспечения, чем меньше требуется нажатий клавиш, тем быстрее и эффективнее программа.

5. A. The faster the key pressings, claim some software producers, the fewer and more efficient the program.

.

  1.  The fewer the key pressings, claim some software producers, the faster and more efficient the program.
  2.  Some software producers claim,  the faster and more efficient the program, the fewer the key pressings.

  •  Give the right Russian equivalent to the following English sentence (Дайте верный русский эквивалент английскому предложению)

This key has different meanings depending on which program is running.

6.  A. Эта клавиша имеет различные значения вне зависимости от выполняемой программы.

    В. Эта клавиша обладает одним и тем же значением при выполнении различных программ.

    С. Эта клавиша обладает различными значениями в зависимости от выполняемой программы.

  •  Find the equivalents in two languages (Найдите эквиваленты в двух языках)

7. extend                          А.  снижать 

8. reduce                          В.  сжать   

9. rotate                            С. увеличивать

10. grip                             D. вводить с клавиатуры    

11. refer                            E. вращать                

                                          F. приписывать

  •  Complete the sentences with the proper word (Закончите предложения подходящим по смыслу словом)

12. The most popular keyboard layout is …….

13.  The mouse is connected to the computer with the help of the

………….

14. The input device, which is helpful for disabled people as they can input data by speaking into a microphone, is known as  ………

15. Input devices that are especially useful for engineers are …….

16. Input device which is very good for copying text and graphic data is called  ……...

17.  A key that moves the cursor  to the beginning of the next line is ……….

18.  DVORAK was proposed in 1932 as a faster and more efficient  ………….

19.  Keys that instruct the computer and are found on most keyboard on their tops are known as ………….

  •  Choose the right variant (Выберете правильный вариант)

20. If you want to put a file into operation you should ……..the mouse button.

  1.  Drag                                        B. Click

C. Double-click                           D. Grab

21. Joystick looks like a ……. with a button on its top.                                    

    A. Lever                                      B. Pen

    C. Tablet                                      D. Box

22. Graphics tablet includes a pen and a board that should be …….

    A. Vertical                         B. Stable

    C. Movable                        D. Flat

23. ……..is an example to copy.

    A. Pattern                      B. View

    C. Image                       D. Device

24. ………are used for changing text material.

    A. Functional keys        B. Editing keys

    C. Alphabetic keys        D. Numeric keys

25. Touchpad has ………. instead of characters                   

    A. Icons                           B. Pictures

    C. Blank spaces               D. Symbols

                


 

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