3.5.8. Keyboard, Mouse

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The KEYBOARD is basic computer peripherals. In it is embedded microcomputer that takes on the care of the management of the keyboard.

Its task is to:

             1. examines key and sends a message about it to the BIOS.
             2. supports two-way serial connection to a computer.

It is possible to use a combination of keys. For it is worth marking follows:

 Way of using multiple keys

Besides pressing <NUM LOCK> in the left corner of the numeric group of characters to the right of the keyboard, allowing you to send the computer codes numbers if bright LED labeled NUM LOCK, or codes of arrows and text if LED does not light.

Whenever you press a key generated code size of one byte that defines the SCAN button keypad code (not the same as the ASCII code) of the example in the table divides the picture again:

 Scan-CODE of keyboard
Table 3.5.23 SCAN-code of PC-AT keyboard.

Meaning of each key is entered into the BIOS, which contains routines for the keyboard. When the button is pressed realized hardware device termination IRQ1, and the activity of the approval of the transfer of the BIOS routines as interrupt vector 9 and performs software routine that starts at the address belonged to him. Keyboard controller is almost always integrated into the motherboard. Scheme standard keyboard without additional function keys shown in the following Figure.

 Marks of keyboard and mouse
Figure* 3.5.24 PC AT keyboard (US layout) and mouse. ( +/- )

Specific LETTER key, sometimes they are different shades of color to the other for purposes of clarity. Illustrative are present:

<ESC> Button which mostly requires interruption in performing tasks.
<CAPS LOCK> Specifies whether to use small or large
            letters. Pressing the button turns the LED on or off
            CAPS LOCK is labeled in the upper right corner
            of the keyboard.
            If the LED lights possible to enter uppercase letters,
            and if the LED is not lit can be input capitalization.
<SHIFT> + <TIPKA PO IZBORU> Selects the upper sign
      code keys with two characters. Allows retrieval of large
      letters if it does not light LED CAPS LOCK. allows retrieval
      lowercase letters when illuminated LED CAPS LOCK.
<TAB> Lets jump the cursor to a specific number of seats
      to the right (usually 8).
<SHIFT> + <TAB> Lets jump the cursor to a specific number
                places to the left (usually 8).
<CTRL> + <TIPKA PO IZBORU> Giving the order to execute
            immediate command in DOS, for example
            <CTRL> + <C> means the end of the tasks in progress.
<ALT> allows retrieval of ASCII characters that are not on
      keyboard, <ALT> + <typing on the numeric set 225>
      and will get the character ''. It should be possible to
      the numeric keypad sends digit codes, which are
      achieved by pressing <NUM LOCK> so bright
      LED labeled NUM LOCK. In applications to
      enter the main menu (the menu).
      The left and right buttons <ALT> usually
      have not the same task.
<ENTER> Contain electronic circuitry keyboard to send
        typed or computer to turn in an application
        accept data on the activation of the selected source or
        in editing a carriage return. Often be both a
        mark <RETURN>
<BS> (<BACK SPACE>) or the arrow on the top left and right
      of letters corner. Pressing the delete
      the selected text from the cursor to the left
      one character.
<SPACE BAR> Long button at the bottom of letters key - Spacebar.
            Scans the blank.

Pressures keys must be quick, because the longer holding the recurring character that belongs to all of the keys while the button is pressed. In this regard one should be very cautious when using the delete key.

FUNCTION keys are generally defined in the application. So, <F1> usually allows the display with extra explanations (HELP) on the task that is to be executed.

The MANAGEMENT key means:

<GROUP OF ARROWS ON THE BOTTOM> Move the cursor (text pointer)
             in the direction of the arrows on the key that was
             pressed. Vertical arrows only work in applications.

<INSERT> Enables or disables insert new text
         between the already existing characters to the point
         where the cursor. In doing so, the cursor changes shape
         (becomes thicker when the insert is enabled), or is
         printed on a place screen messages about the current
         status of key (INS = insert or OVR = overwrite).
<DEL> (<Delete>) the button which deletes the character as to
       be 'sucked' the right side of the cursor. The keyboard
       has two keys enabling this peculiarity, with key
       <Del> part of numerical set entered a decimal point
       (comma) when the NUM LOCK peculiarity active.
<HOME> Use Sets the cursor to the beginning of the current line.
<END>  Sets the cursor to the end of the current line.
<CTRL> + <HOME> and <CTRL> + <END> sets the cursor
                at the beginning or end of the file.
                Used in applications.
<PAGE UP> Scrolls the display text or form on the screen for
          one screen towards the beginning of the text or shape.
          Has a purpose in applications.
<PAGE DOWN> Scrolls the display text or forms on screen
            one screen towards the end of the text or form.
            Has a purpose in applications.

NUMERIC buttons have two functions, depending on whether the NUM LOCK peculiarity is active or not. A darker NUMERIC buttons contain operators for computation, and the <ENTER> key with the same task as the corresponding key at group of letters key. If the function NUM LOCK off (does not light LED) numerical set is transformed into a set of keys and cursor editor.

In addition, the use and combination of three CONTROL buttons as follows:

<PRINT SCREEN> Orders printing the screen contents in DOS
               or sends the screen contents to a temporary storage
               a data transfer rate (CLIPBOARD) in
               working memory in Windows.
<CTRL> + <SCROLL LOCK> Stops program execution.
<PAUSE> (<BREAK>) Three key functions. Stops printing
                  data on the screen e.g. by command DIR.
<CTRL> + <PAUSE> Resumes printing stopped
                 using the key <PAUSE>.
<CTRL> + <BREAK> Interrupted task that is currently executing,
                 as a combination of keys <CTRL> + <C>.

Market competition has resulted in a different type of keyboard, the function keys are added for direct program support, or are not part of the key is installed in order to be more compact, and adds wireless support and the like. But essentially the outside for years remains unchanged. What we should pay attention to is that the keys are not too hard to type, the keyboard is easy to clean and that the letters do not remove tags. All the popular black keyboard with white markings on the keys.

Interface with which the keyboard and mouse are connected mainly PS/2 (IBM Personal System /2), the standard of which is taken from the PS/2 series of IBM personal computers. Until then, they are used to the keyboard DIN connectors, and a serial port for the mouse. Today, the rule uses the USB interface for mouse and keyboard. USB interface offers the convenience that devices can be turned on or off 'in hot', with the newer devices is directly supported by the BIOS and how it could be accessed by configuring the basic settings of your computer. Users usually more comfortable working in the office or at home using a USB keyboard and mouse when using a notebook (laptop).

Addition of a computer MOUSE is of fundamental importance in the Windows GUI or the like, and its presence is detected by the POINTER within the graphical user interface on the monitor screen. The basic principle of operation was to date the opto-mechanical system with a ball. This mechanism, quite fond of dirt, effectively replacing the system with a mini-camera that determines the direction of movement of the mouse on the basis of comparison of the difference in the picture of the door is a mouse, brought about by moving the mouse. The mouse is not determined by its absolute position on the screen, but the direction of movement relative to its initial position the POINTER, and the accompanying support program can adjust how fast and how much fine will accompany these changes. The pointer is usually an ARROW indicates which TOP his current position on the screen. As the mouse moves, so moves the pointer and mouse. The role of the mouse that accurately indicates the individual part of a GUI or graphical object, and to help the user perform commands and application related to that object as activation programs, selection of commands, open additional menus and other operations using the buttons built into it. With the keyboard, the mouse is the most important input device PC. It basically has two buttons, left and right-L-D which, by definition, the actions in the operating system, with one or two clicks (further action L1, L2, D1, D2 ...) at key to achieve different actions, choices and views. A mouse over the Chapter on Windows.

That mice with the optical system does not require a precise contact with the surface, they do not need a special background as code opto-mechanical version, but they do not fit reflective surfaces like glass. Plain sheet of paper on the glass is sufficient as a basis for an optical mouse. Apart from the basic version with two keys, all the more a part of 'standard' equipment center button mouse-wheel (action K1, K2) with the basic task of a quick overview of document content. But for the 'players' are versions that enrich the functionality of the mouse, in different ways, the most common additional keys, which is required to install a non-standard program support for the mouse. And for the 'players' are designed and special mouse mat that enable more accurate and faster keeping the cursor. Mouse is shown in Figure 3.5.24 is not the only way to use this principle in working with a personal computer. Used more 'trackball' (balls on the top of 'mouse'), touch pad (touchpad) in combination with small buttons, and small crank similar gaming joystick. 'Trackball' can be incorporated into the keyboard casing and the previously mentioned solutions are mostly peculiarity laptops.


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