COMPUTER ORGANISATION
A computer is an organized set of activities. A computer system consists of following elements:
1. HARDWARE
2. SOFTWARE
HARDWARE: The physical equipments and components which we can see, touch and feel in computer system are called hardware. Hardware is divided into four parts-
1. Input device
2. Output device
3. Processing device
4. Storage device or memory
1. INPUT: This is the process of entering data and programs in to the computer system. Computer is an electronic machine like any other machine which takes as inputs raw data and performs some processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing.
Computer work on binary data (data having only 2 forms). It uses only two digits 0 and 1. as computer is an electronic device 0 is represented as off and 1 by on state. All input devices must provide a computer with data that are transformed into binary codes that the primary memory of a computer is designed to accept.
Thus an input unit performs the following task:
• It accepts the list of instructions and data from the user.
• It converts these instructions and data in computer acceptable form.
• It supplies the converted instructions and data to the computer system for further processing.
Keyboard is an ideal example of an input device.
KEYBOARD: Keyboard is an ideal example of an Input Device. The standard layout of letters, numbers, and punctuation is known as a QWERTY keyboard because the first six keys on the top row of letters spell QWERTY. The QWERTY keyboard was designed in the 1800s for mechanical typewriters and was actually designed to slow typists down to avoid jamming the keys.
The keys in a keyboard can be broadly classified in three categories:
• FUNCTION KEYS: These keys are usually on the top-most row labeled F1 to F12. A function key is a key on a computer or terminal keyboard which are programmed so as to cause an operating system command interpreter or application program to perform certain actions. The F1 key gradually became universally associated with Help in most early Windows programs.
• TYPEWRITER KEYS: The major portion of keyboard has the normal typewriter like keys. It contains all the alphabets, numbers and punctuation symbols.
• NUMERIC KEYS: This group is on the right side of the keyboard and resembles. A calculator keyboard with numbers 0 to 9. this group of keys helps to enter numeric data single-handedly. This pad works as the cursor control also. Pressing NUMLOCK key toggles between cursor control pad and numeric keypad.
OTHER KEYS ON A COMPUTER KEYBOARD:
Esc:
Equivalent to clicking the Cancel button. In PowerPoint the Esc key will stop a running slide show. On a web page with animations, the Esc key will stop the animations. On a web page that is loading, the Esc key will stop the page from loading. The keyboard combination Ctrl + Esc will open the Start Menu.
Print Screen/SysRq:
Usually located at the upper right hand corner of your keyboard next to the Scroll Lock and Pause/Break keys. Often abbreviated Prt Scr, the Print Screen key is a useful key supported on most PCs. In DOS, pressing the Print Screen key causes the computer to send whatever images and text are currently on the display screen to the printer. Some graphics programs and Windows, use the Print Screen key to obtain Screen Captures.
Scroll lock: When the scroll lock mode was ON, the arrow keys would scroll the contents of a text window instead of moving the cursor as usual.
Tab:
This key can be used to move forward through options in a dialog box.
Ctrl + Shift + Tab can be used to move backward through the options.
Ctrl + Tab allows movement from one open window to the next in an application with more than one open window.
Alt + Tab displays a list of open application windows. Keeping Alt depressed and selecting Tab cycles through the list. Releasing selects the highlighted application window.
Caps Lock:
Locks the keyboard in "Capitals" mode (only applies to Alpha keys). The Caps Lock key should be used with caution. Using ALL CAPS is a usability no-no as many have difficulty scanning text that is ALL CAPS. Also, when sending email in all caps, this could be misconstrued as shouting at someone.
Shift:
The obvious use of this key is to allow selection of capital letters when depressing the alphabet characters, or selecting the characters above other non-alpha keys.
Depressing the Shift key while inserting a CD-ROM will bypass auto play.
Shift + Delete to permanently delete a selected item, bypasses the Recycle Bin.
Space Bar:
Insert a space between words. It is suggested that you utilize Tabs (or other formatting commands) to put distance between elements. Using the space bar to insert visual space works but would not be considered a best practice in page design. Double spaces between sentences are no longer required. This is a carryover from the days of fixed width fonts on a typewriter such as Courier, Orator, Prestige Elite, etc.
Pressing the Space Bar while viewing a web page in Internet Explorer will scroll the page downwards. Shift + Space Bar will scroll the page upwards.
Backspace:
While working with text, use this key to delete characters to the left of the insertion point.
Insert:
In MS Word the characters typed from keyboard are inserted at the cursor position. As you type any text, the existing characters shifts to the right hand side to make space for newly inserted characters.
Home:
Depress and hold the Ctrl key as you select Home to go to the first line of a document.
Page Up:
In a browser window use the Page Up key to move up one full screen on a web page.
Delete:
While working with text, use this key to delete characters to the right of the insertion point. This key can also be used to delete selected files. If you use the keyboard combination Shift + Delete the item is permanently deleted, bypassing the Recycle Bin.
End:
Depress and hold the Ctrl key as you select End to go to the last line of a document.
Page Down:
In a browser window use the Page Down key to move down one full screen on a web page.
Up Arrow:
Navigate in a document to the line above. Hold the Ctrl key down as you press this key to move to the beginning of the second line above.
Right Arrow:
Navigate in a document one character to the right. Hold the Ctrl key down as you press this key to move one word to the right.
Down Arrow:
Navigate in a document to the line below. Hold the Ctrl key down as you press this key to move to the beginning of the second line below.
Left Arrow:
Navigate in a document one character to the left. Hold the Ctrl key down as you press this key to move one word to the left.
