Fundamental

How does a computer work?
Computer work in almost the same way as most machines do.
A computer has 3 units, the INPUT, the PROCESS, and the OUTPUT, as shown below:

Each unit is followed by the next.
A computer can work only if it is given an input. The computer processes this input and given an output.In the input is bad or incorrect, the output will also be bad and incorrect .In computer terms, this is called GIGO. – Garbage in, Garbage OUT! (‘Garbage’ means ‘waste’ or ‘rubbish’). Moreover, if wrong instructions are given, the computer will give only wrong results.

Hardware:
The physical components of a computer is known as hardware, such as  physical components may be electrical , electronic, magnetic, mechanical or optical some such parts are microprocessors , Integrated Circuits (IC),Hard disk , Floppy disks, Optical disks, Monitors, Keyboard , Printers etc..

Parts of a Computer:

Figure 6 Desktop Computer
The figure 6 shows the basic parts of a computer. Let us take a closer look at these.

Input Devices:
The data and instructions are entered into the computer through input devices and input devices first converts desired input data and instructions into suitable binary form (0…1) and then feed into the CPU. The commonly used input device is keyboard. A number of other input devices have been developed that don’t require typing. These are mouse, joy stick, trackball, light pen, touch screen etc.

Keyboard:
The keyboard is the most common input devices and is an essential part of any computer. The programs and data are entered into a computer through keyboard, which is attached to a computer. A keyboard is a very similar to be a keyboard of type writer. It has letters, numbers and special character, function keys and some control keys.

Figure 7 Keyboard

The keyboard also has a set of four keys with arrows on them. These keys are called the Cursor movement keys.
There are twelve keys called Function keys, which have special uses, as you will see later.
The keyboard also has another set of numbered keys that are similar to the keys found on a calculator.
Apart from these, there are other keys like Insert, Home, Ctrl, etc.these help in doing specific tasks.
The keyboard provides different keys to perform various operations (refer table 1.1)

y	Function
F1-F12(Function keys)	Used to perform special functions that depend on the software being used
Enter	Used to execute an instruction or data being keyed In through the keyboard
Caps lock	Used for keying in capitalized alphabets.
Shift	Caps lock off: if pressed simultaneously with a character key, a capitalized Alphabet is input. Caps lock on: it reverse the above effect. Also used to input the upper symbols for keys with two symbol or character on them.
Ctrl, Alt	Pressed with other keys, they input special messages to the computer.
Backspace	Used to erase the character to the left of the cursor position.
Numlock	Used to active the numeric keys on the numeric keypad.
Cursor keys (¬,­,®,¯)	Used to move the cursor in the direction indicated.
Home	Used to move the cursor to the left end of the current line.
End	Used to move the cursor to the end of the current line.
Page UP	Used to move the cursor up one page or one screen.
Page Down	Used to move the cursor down one page or one screen.
Insert	Used to insert characters at the current cursor position.
Del	Used to delete characters at the current cursor position.
Esc	Depends on the applications. Usually used to cancel a command.
Print Screen	Used to print whatever is displayed on the screen
SysRq	System Required depends on the application.