UNIT- 1( Introduction to Computers )

                                                                  UNIT- 1

                                    Introduction to Computers

In today’s society, we depend a lot on the computers and technology for our daily chores.
This chapter would give a brief introduction to the computers.

                                 Building Blocks of ComputeR

Computer:- A computer can be defined as an electronic device with the ability to:- 

1. Accept user­supplied data and instructions. 
2. Store data and perform mathematical/logical operations. 
3. Output results according to user specifications. 
4. Transfer data, images and sound through telephone lines or cables at a fast rate.

CPU :-

The heart of a computer is the Central Processing Unit (CPU).
CPU or Central Processing Unit: The CPU is housed inside a box­like structure called the "System Unit".

It is responsible for all the processing required to receive and convert the input to the required output.

It performs all the arithmetic calculations and logical operations.
It also coordinates and controls the other devices of the computer.
The memory of the computer is housed inside the CPU.

The CPU is comprised of three components, namely,
Memory Unit ,Control Unit, Arithmetic and Logic Unit.

Memory Unit:-

The Memory unit stores program or data in a computer or any other physical storage
medium.

Control Unit:-

The control unit directs and controls the activities of the internal and external devices.

ALU :-

Arithmetic Logic Unit (ALU) is the part of the CPU, where the actual computations take place.

While performing these operations the ALU takes data from the temporary storage area. inside the CPU named registers.

The speed of the processor or the clock rate is measured in megahertz (MHz) or million ticks per second.

Binary Numbers

The computer stores a character in the storage cells with binary (0, 1) mechanism.
Thus the basic unit of memory is a bit (binary digit–0, 1).
To store a character, a computer requires 8 bits or 1 byte.
This is called the ― word length‖ of the storage unit.
Hence the storage capacity of the computer is measured in the number of words it can store and is expressed in terms of bytes.

The different units of measurement are,

8 Bits =1 Byte
1024Bytes = 1 Kilo Byte (KB)
1024 KB = 1 Mega Byte (MB)
1024 MB = 1 Gega Byte (GB
Any piece of equipment that provides data and control signals to the computer is an input device.

The following are the examples of input devices: Mouse, Keyboard, Joystick, Scanner, Web, Camera, Microphone.

Mouse:-

Mouse is an input device that is used to point and select items or objects displayed on the

monitor:-

Mouse that are used with the desktop computers have two or three buttons.
Some mice have a wheel between the left and right buttons and is called scroll mouse or wheel mouse.
The left button of the mouse is also known as Primary mouse button and the right button of the mouse is known as Secondary mouse button.
The scroll wheel is located between the buttons.

Features of Mouse:-  

A mouse has some basic operational features irrespective of the number of Binary Numbers Input devices

                   

buttons the mouse has.
They are:
Moving the mouse pointer,
Pointing,
Clicking,
Left clicking,
Right clicking,
Double clicking,
Dragging and Dropping,
Keyboard

The Keyboard, also called as the standard input device, is a series of switches connected to a microprocessor that monitors the state of each switch and initiates a specific response to a change in that state.
Each keystroke generates a unique signal, which is used by the computer to identify the key pressed.

Joystick:-

This joystick is an input device.
It is a lever that moves in all directions.
It controls the movement of the cursor.
With a joystick, the pointer continues moving in the direction the joystick is pointing.
Pointer can be stopped if the joystick is placed in its upright position.
The buttons on the joysticks are called triggers.

Scanner:-

Scanner is an input device that is used to make an exact copy of a picture or a photograph in a paper to the computer.
There many models of scanners available and used for different scanning requirements.
The most common types of scanners are handheld scanners and flatbed scanners.

Web Camera:-

A Web camera is a device capable of converting visuals into digital form.
Web cameras are generally mounted on top of a computer monitor and function as the eye of the computer.