Computer:-A computer can be defined as a fast electronic calculating machine that accepts the (data) digitized input information process it as per the list of internally stored instructions and produces the resulting information.List of instructions are called programs & internal storage is called computer memory.
The different types of computers are:-Personal computers: – This is the most common type found in homes, schools,
Business offices etc., It is the most common type of desk top computers with
processing and storage units along with various input and output devices.
Note book computers:- These are compact and portable versions of PC
Work stations:- These have high resolution input/output,graphics Capability, but with same dimensions as that of desktop computer. These are used in engineering applications of interactive design work.
Super computers:- These are used for large scale numerical calculations
required in the applications like weather,forecasting etc.
A computer consists of five functionally independent main parts input, in ioutput, memory, arithmetic logic unit (ALU) and control unit.
Input Unit:-All those devices which are used to input data into the computer system called input device and this unit is called input unit.
Input unit is used to send data to the computer.
The main tools are Keyboard, Mouse, Scanner, Optical Mark and Light Pen etc.
Output Unit:-All those devices which are used before and after processing to view information and results permanently or temporarily called output device.
Commonly used as output are Monitor, Printer, Delineator etc.
Memory:-A memory unit is a unit of a computer system that stores the data inputted by the input unit before processing it on the data and during processing and after processing either permanently or temporarily.
Its function into store programs and data.
It is basically to two types
1. Primary memory
2. Secondary memory
1.Primary memory:- Primary memory is memory by which data, information, and programs are temporarily stored. Primary memory is the total amount of memory installed on a computer.
It contains the programs that are currently being run and the data the programs are operating.
2.Secondary memory:- Is used where large amounts of data & programs have to be
stored, particularly information that is accessed infrequently.
Examples: – Magnetic disks & tapes, optical disks, floppies etc.Arithmetic logic unit (ALU):-Most of the computer operators are executed in ALU of the processor like addition, subtraction, division, multiplication, etc. the operands are brought into the ALU from memory and stored in high speed storage elements called register. Then according to the instructions the operation is performed in the required sequence.Control unit:-It effectively is the nerve center that sends signals to other units and senses their states. The actual timing signals that govern the transfer of data between input unit, processor, memory and output unit are generated by the control unit.
Computer Hardware:-Physical elements of computer that we can see and touch are called Computer hardware.
Computers do not exist without hardware,Because a computer can be completed only after meeting them.
Internal Hardware:- Internal components that are not usually visible to us as they are present inside the computer case.
To see them, we have to open the computer.
The list of internal hardware is given below-
Central processing unit (CPU)
External Hardware:-External components, also called peripheral components, are associated with computers from outside. These include Input and output device, whose list is given below-
Computer Software:-Software is a collection of computer programs that provide instructions to the computer about what to do and how to do it.
That is, the software acts as an interface between the user and the computer.
It is a set of instructions, which are used to give commands to the hardware.
Through this, we get the desired output.
There is two type of computer software-
System Software:- It consists of the default programs of the computer which handle the basic functions of the computer.
They are responsible for controlling, integrating and managing the individual hardware components of a computer system.
That is, the main function of system software is to manage and control the hardware components so that the application software can do its work properly.
Application Software:-This is a software that has been developed to help users and it can perform only one specific task.
Such softwares are called application software.
This is completely different from System Software.
Where System Software runs in the background, Application Software runs in the front end and it is also visible to the users.