Wednesday, April 3, 2013

Keyboard


The keyboard is intended for information input in the computer. On it it is possible to allocate the following groups of keys:

  • the main;
  • the auxiliary;
  • group of cursor arrows;
  • group of function keys [F1] – [F12].


On the main part of the keyboard there are alphanumeric keys, and an arrangement of Latin letters on the IBM PC keyboard, as a rule, same, as on the English typewriter, and Cyrillics letters – as on the Russian typewriter.

Often during the work it is necessary to use the same team repeatedly. To replace routine work of the user on input of such repeating teams function keys [F1] – [F12] (F1 – F10 are usually used only), the keyboards which were in the top part are used. For example, the key [F1] in all programs is used for a reference call.


Cursor arrows allow to move the cursor in the necessary direction.

Keys [↑], [↓], [←], [→] serve for cursor movement respectively up, down, to the left and to the right.

Keys [PageUp], [PageDown] serve for paginal movement on the screen up and down (for example, browsing of the text represented on the screen).

Keys [Home] and [End] are intended for moving of the cursor to the beginning and the end of lines, respectively.

The key [Delete] (delete – removal) is used for removal of a symbol on which there is a cursor. Thus the cursor remains on a former place, and all symbols to the right of the cursor move on one position to the left.

The key [Insert] (insert – an insert) is intended for transition from an insert mode in a mode of replacement and back. In an insert mode entered symbols appear on that place where the cursor is located, and the part of a line located to the right of the cursor, moves by each pressing of a key one position to the right. In a mode of replacement of shift of the text located to the right of the cursor, doesn't occur, and entered symbols appear on a place old, rubbing clean them.


The auxiliary keyboard is usually used during the work with the programs having the built-in calculator, and also at input of big massifs of numbers. Digital keys on an accessory of the keyboard are combined with keys [Ins], [Del], [Home], [End], [PgUp], [PgDn] and cursor arrows. Besides, the key [Num Lock] serving for switching from a digital mode in control mode as the cursor and back here is located. By pressing this key in the right top corner of the keyboard the indicator corresponding to an inscription of "Num Lock" which indicates transfer of the auxiliary keyboard to a digital mode lights up.


Special keys of the keyboard. Except the listed keys on the keyboard there is a large number of special keys. Let's shortly consider purpose of these keys.

The key [Enter] (input) is intended for transfer of the cursor to the beginning of the next line. Besides, this key is used for input of teams.

The key [Shift] serves for input of the header and other symbols which are settling down in the top register of the keyboard.

The key [Back Space] is represented by an arrow to the left over a key [Enter]. By pressing this key the cursor moves on one position to the left and erases a symbol being in this position.

The key [Esc] (escape – an exit, rescue, escape), is located in the left top corner of the keyboard and serves for cancellation of actions.

To move the cursor on some (usually, 4 or 8) positions to the right, it is possible to use a key of tabulation [Tab].

To increase quantity of commands executed by means of function keys, keys are used:

[Ctrl] – from the English word Control (management);

[Alt] – from the English word Alternative (alternative).

These keys as well as key [Shift], are intended for changes of values of other keys. They are used in a combination with other keys, and thus carried-out program can react to these combinations in a special way.


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