CBSE Book Class 11 Informatics Practices Hardware Concepts

Hardware Concepts

Our present day life is so automatic that most of the tasks are accomplished with a click of a button. Washing has been taken over by washing machines, cooking by microwaves, conventional banking has been replaced by ATMs etc. In every sphere of life, machines dominate human efforts. Have you ever wondered what mechanism works behind these machines? In fact, in all these machines, a click of button starts a process inside the machine which sometimes can be very complex one. It does exactly what is required as it follows a predefined work flow based on which button has been pressed. Let us take the case of cash withdrawal from a bank ATM. The user is required to press only a few buttons to authenticate his identity and the amount he wishes to withdraw. Then within seconds the money pops out of the ATM. During this process, the inside working of bank ATM is beyond imagination of the user. Broadly speaking, the ATM receives certain data from the user, processes it and gives the output (money). This is exactly what a computer does. Formally, a computer can be defined as follows:

A computer is an electronic device that processes input data and produces result (output) according to a set of instructions called program.

A computer performs basically five major functions irrespective of its size and make.

It accepts data or instructions by way of input

It stores data

It processes data as required by the user

It controls operations of a computer

It gives results in the form of output

In order to carry out the operations mentioned above the computer allocates the task among its various functional units.

The above diagram describes the basic layout of a computer. A computer receives data and instructions through "Input Devices" which get processed in Central Processing Unit, "CPU" and the result is shown through "Output Devices". The "Main / primary Memory" and "Secondary / Auxiliary Memory" are used to store data inside the computer. These are the basic components that each computer possess. Each of these components exists in various types and variety that differ in shape, size, usage and performance. The user makes a choice according to his specific requirement. Now we will discuss each component in detail.

Input Devices

These are used to enter data and instructions into the computer. Let us discuss some of them.

Keyboard

This is the most common input device which uses an arrangement of buttons or keys. In a keyboard each press of a key typically corresponds to a single written symbol. However some symbols require pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or characters, other keys or simultaneous key presses can produce actions or computer commands.

In normal usage, the keyboard is used to type text and numbers while in a modern computer, the interpretation of key press is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports the key-presses to the controlling software. Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features. Apart from alphabet keys (26 keys), there are several other keys for various purposes such as

Number keys - The 10 number keys 0-9 are there on each keyboard. Sometimes, there are two sets of these keys.

Direction keys - There are four direction keys : left, right, up and down which allow the curser to move in these directions. Unlike alphabet and number keys, these keys do not display any thing.

Function keys - There are generally 12 functions keys F1-F12. These keys have special tasks and the tasks may change from program to program. Just like direction keys, these too do not print anything.

Other keys - There are several other non-printable keys for various different purposes. These include caps lock, tab, ctrl, pause, delete, backspace, spacebar, shift, enter etc which are used for special purposes.

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