COMPUTER SYSTEM AND ITS COMPONENTS

Computer is an  electronic machine used to solve different problems according to  a set of instructions given to it. A computer can accept data , process data into useful information and store it for later use.
The word computer derived from COMPUTE that means to calculate.
A computer system consists of mainly four basic units.
1: storage unit
2: central processing and output unit.
3: Central Processing unit further includes Arithmetic logic unit and control unit
4: input unit
 A computer performs five major operations or functions irrespective of its size and make.
1: it accepts data or instructions as input,
2: it stores data and instruction,
3: it processes data as per the instructions,
4: it controls all operations inside a computer, and
5: it gives results in the form of output.

FUNCTIONAL UNITS:
 Input Unit: This unit is used for entering data and programs into the computer system by the user for processing.

 Storage Unit: The storage unit is used for storing data and instructions before and after processing.

 Output Unit: The output unit is used for storing the result as output produced by the computer after processing.

 Processing: The task of performing operations like arithmetic and logical operations is called processing. The Central Processing Unit CPU takes data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit. CPU includes Arithmetic logic unit  and control unit 

• Arithmetic Logic Unit: All calculations and comparisons, based on the instructions provided, are carried out within the Arithmetic Logic Unit. It performs arithmetic functions like addition, subtraction, multiplication, division and also logical operations like greater than, less than and equal to etc.

Control Unit: Controlling of all operations like input, processing and output are performed by control unit. It takes care of step by step processing of all operations in side the computer.

MEMORY

computer memory can be classified into two types:

 primary memory and secondary memory.

RAM:

 Primary Memory can be further classified as RAM and ROM

 RAM or Random Access Memory is the unit in a computer system. It is the place in a computer where the operating system, application programs and the data in current use are kept temporarily so that they can be accessed by the computer’s processor. It is said to be ‘volatile’ since its contents are accessible only as long as the computer is on. The contents of RAM are no more available once the computer is turned off.

ROM or Read Only Memory is a special type of memory which can only be read and contents of which are not lost even when the computer is switched off. It typically contains manufacturer’s instructions. Among other things, ROM also stores an initial program called the ‘bootstrap loader’ whose function is to start the operation of computer system once the power is turned on.

b. Secondary Memory

RAM is volatile memory having a limited storage capacity. Secondary/auxiliary memory is storage other than the RAM. These include devices that are peripheral and are connected and controlled by the computer to enable permanent storage of programs and data.

INPUT  AND  OUTPUT  DEVICES: 

These devices are used to enter information and instructions into a computer for storage or processing and to deliver the processed data to a user. Input/Output devices are required for users to communicate with the computer. In simple terms, input devices bring information into the computer and output devices bring information  of a computer system. These input/output devices are also known as peripherals since they surround the CPU and memory of a computer system.

Input Devices

An input device is any device that provide input to a computer. There are many input devices  but the two most common ones are a Keyboard and Mouse. Every key you press on the keyboard and every movement or click you make with the mouse sends a specific input signal to the computer.

KEYBOARD:

• Keyboard: The keyboard is very much like a standard typewriter keyboard with a few additional keys. The basic QWERTY layout of characters is maintained to make it easy to use the system. The additional keys are included to perform certain special functions. These are known as function keys that vary in number from keyboard to keyboard.

MOUSE

 Mouse: A device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard and flat surface. Its name is derived from its shape, which looks a bit like a mouse. As you move the mouse, the pointer on the display screen moves in the same direction.

TRACKBALL:

Trackball: A trackball is an input device used to enter motion data into computers or other electronic devices. It serves the same purpose as a mouse, but is designed with a move able ball on the top, which can be rolled in any direction.

TOUCH PAD:

• Touch pad: A touch pad is a device for pointing (controlling input positioning) on a computer display screen. It is an alternative to the mouse. Originally incorporated in laptop computers, touch pads are also being made for use with desktop computers. A touch pad works by sensing the user’s finger movement and downward pressure. • Touch Screen: It allows the user to operate/make selections by simply touching the display screen. A display screen that is sensitive to the touch of a finger or stylus. Widely used on ATM machines, retail point-of-sale terminals, car navigation systems, medical monitors and industrial control panels.

Scanner:

Scanner is an input device that can read text or illustration printed on paper and translates the information into a form that the computer can use. A scanner works by digitizing an image.