|History & Civics|
A computer is an electronic device,which can perform a variety of operations according to a set of instructions called program.
A computer program is a set of instructions given to computer to perform some operations.
Data are raw facts and figures.Data processing system transforms data into useful information.
The processed data is known as Information.It means what we get after processing data(meaningful data).Data are aggregated and summarized in various meaningful ways to form information.
Data is raw information or a collection of facts. For example, In a Super 66 draw the balls that are drawn are all individual pieces of data.
Information is the processed data that has passed through the IPC. It is meaningful and allows an organisation to make decisions and solve problems. For example, when all six drawn balls are placed in their correct order, they become a piece of information.
Hardware represents the physical and tangible components of the computer i.e, the components that can be seen and touched. The electronic, electrical and mechanical equipment that makes up a computer is called hardware. Input devices, output devices,CPU, floppy disk, hard disk etc. are examples of computer hardware.
A computer consists of five primary hardware components:
♦ Input devices
♦ CPU (Central Processing Unit)
♦ Output devices
♦ Storage devices
Software represents the set of programs that govern the operation of a computer system and make the hardware run. Software can be classified broadly into three categories:
♦ Operating system
♦ Language Processors
♦ Application Software.
Hardware are physical tangible components of a computer system.Software are the computer programs that govern the operation of computers.Firmware are the prewritten programs permanently stored in read-only memory .These configure the computer and are not easily modifiable by the user .
Four Functions about computer are:
accepts data Input
processes data Processing
produces output Output
stores results Storage
Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.
Process is the operation of data as per given instruction. It is totally internal process of the computer system.
Output is the processed data given by computer after data processing. Output is also called as Result.
We can save these results in the storage devices for the future use.
A computer mainly has four functions :
1.Accept Data - Input
2.Processes Data - Processing
3.Produces Result/Output - Output
4. Stores Result - Storage
The first stage is performed in computer by input unit,second stage is performed by the central processing unit and the third stage is performed by output unit.And all this is done with the help of memory.Memory is the brain of computer which holds the data during processing.
5. High storage capacity
1. Lack of decision-making power.
2. Zero IQ.
The four fundamental components of a computer system are :
(i) Input unit
(ii) CPU(Central Processing Unit)
(iii) Internal memory
(iv) Output unit
Computers are categorized into following types of computers:
(i) Embedded Computers are embedded within the circuitry of appliances such as televisions,washing machines and wrist watches etc.
(ii) Programmable Computers can be used as notepads,scheduling systems,address books etc.With cellular phones these can connect to worldwide computer networks to exchange information regardless of location .
(iii) Laptop Computers and Personal computers are typically used in business and at home to communicate on computer networks ,for word processing to track finance,to play games etc.
(iv) Workstations are similar to PCs but have more capabilities.These are typically found in scientific ,industrial and business environments that require high levels of computational abilities.
(v) Mainframes are even more capable than workstations and can be used by multiple users.
(vi) Supercomputers are the most powerful computers that are used to process complex and time consuming calculations.They a reused by the largest business institute / houses,scientific institutions and the defence.
Laptop computers or notebooks provide a user mobility as well as essentially the same processing capabilities as a desktop personal computer.
|Computer Type||Used By|
Universities,Large Research companies, Military , Largest businesses.
Utility companies , Bank
Business , Employees,Students in school,People at home
|Personal Digital Assistant (PDA)||
Personal Digital Assistant(PDA)
Most Powerful Supercomputer
Desktop Personal Computer
Least powerful Embedded Computer
CPU,control unit,query,English ,training,formula,alu,processor,memory,operating system,windows XP.
Hardware : CPU,Control Unit , ALU,Processor, Memory
Software : Operating System , Windows XP,Query.
The basic units of a computer are:
The CPU has two subunits: the control unit (CU) and the arithmetic logic unit (ALU).
The control unit controls the entire operation being carries out.
The ALU performs the arithmetic and logical operations.
A computer follows the input - process - output cycle.The first stage is performed in computer by input unit,second stage is performed by its central processing unit and the third stage is performed by output unit.The basic structure of a computer is shown below :
The main memory holds the input and intermediate output during the processing.
The input unit is formed by the input devices attached to the computer.Examples of input devices are : Keyboard,Mouse,Magnetic ink character reader(MICR),optical mark reader(OMR),optical character reader(OCR),joystick etc.
The input unit is responsible for taking input and converting it into computer understandable form.
Central Processing Unit(CPU) :
The CPU is the control centre for a computer.It guides,direct and governs its performance.It is the brain of the computer.The CPU has two components which are responsible for different functions,These two components are its Control Unit (CU)and Arithmetic Logic Unit(ALU).
Output Unit :
The output unit is formed by the output devices attached to the computer.The output coming from the CPU is in the form of electronic binary signals which needs conversion in some form which can be easily understood by human beings that is characters,graphical or audio visuals.This function of conversion is performed by output units.Examples of output units are VDU(Visual Display Unit),Printer,Plotter etc.
Memory - also known as the primary storage or main memory, is a part of the microcomputer that holds data for processing, instructions for processing the data (the program) and information (processed data). Part of the contents of the memory is held only temporarily, that is , it is stored only as long as the microcomputer is turned on when you turn the machine off, the contents are lost. The capacity of the memory to hold data and program instructions varies in different computers.
The ALU performs all the four arithmetical ( +, -, *, /) and some logical (, =, < =, > =, < >) operations. When two numbers are required to be added, these numbers are sent from memory to ALU where addition takes place and the result is put back in the memory.
For logical operations also, the numbers to be compared are sent from memory to ALU where the comparison takes place and the result is returned to the memory. The result of a logical operation is either TRUE or FALSE. These operations provide the capability of decision-making to the computer.
The CU controls and guides the interpretation, flow and manipulation of all data and information. The CU sends control signals until the required operations are done properly by ALU and memory. The CU gets program instructions from memory and executes them one after the other. After getting the instructions from memory in CU, the instruction is decoded and interpreted that is ,which operation is to be performed. Then the asked operation is carried out. After the work of this instruction is completed, control unit sends signal to memory to send the next instruction in sequence to CU. The Control unit even controls the flow of data from input devices to memory and form memory to output devices.
The memory temporarily holds the data and information during processing.The smallest unit of memory is a byte (8bits). A byte can store one character in binary form. Other measuring units are kilobyte (KB) equal to 1024 (210) bytes, Megabyte (MB) equal to 1024 KB Gigabyte (GB) equal to 1024 MB and Terabyte (TB) equal to 1024 GB