Fundamentals of computing

Fundamentals of computing

Introduction to computersComputer-derived from a Latin word computare which means to compute or to calculate

DefinitionThe computer is an electronic device which converts raw data into valid (or) meaningful information.

basic operations of a computerInput : It is the process of capturing or acquiring the raw data.Process :It is the transformation process to convert the input into output.Output :It is the result, which comes from the transformation process or it is the outcome of the process.Storing: It is the process of saving the data or information or instruction , so that they can be retained and retrieved whenever required.Controlling: It is the process of directing the manner and sequence in which all the operations are to be performed.

Characteristics of a ComputerSpeedSpeed is the most important characteristics of a computer. Computers have more speed to perform jobs instantaneously. It can perform in a few seconds , the amount of work that a human being can do in an entire year.

A powerful computer is capable of adding two twenty digit numbers in 300 nano seconds

characteristics of a computerAccuracy

The accuracy of the computer is consistently high. The computers are perfect accurate and precise. It never makes any mistake.

Automatic

The computer works automatically, once programs are stored and data given to it. Constant supervision is not required .Individual instructions are transferred one after other to the control.Characteristics of a computerDiligence

The computer can go working continuously and does not suffer from human traits of tiredness and lack of concentration. If three million calculations have to be performed ,it will perform the third millionth instruction with exactly the same accuracy and speed as the first instruction.Characteristics of a computerVersatility

The computer can be put to various jobs and has applications in various fields.

Computers have key role in fields such as space exploration, weather forecasting,research,office automation,teaching,railways,medicine,industry, and banking.characteristics of a computerStorage

The computers processes limitless quantities of data and information. With more and more auxiliary storage devices, which is capable of storing huge amount of data ,the storage capacity of computers is unlimited.classification of computersbased on size and capacityMicro computer

Minicomputers

Mainframes

Super computers

Microcomputers

Smaller computersCPU is usually a single integrated circuit

Minicomputer

Minicomputers are scaled up version of micro computers with moderate speed and storage capacity

classification of computersbased on size and capacityclassification of computersbased on size and capacityMainframe

Mainframe computers are implemented using two or more central processing units.It is capable of supporting hundreds of users simultaneously.

Supercomputer

A supercomputer is an extremely fast computer that can perform hundreds of millions of information's per second.

classification of computersbased on utilityGeneral Purpose computersSpecial purpose computersclassification of computersbased on hardware designAnalogDigitalHybrid

classification of computersbased on mode of usePalmtop PCSLaptop PCsPersonal computerWork stationMainframe systemClients and Servers

Basic computer organizationThe architecture of the computers have not changed but the technology used to accomplish those operations may vary from one computer to another.However, the basic computer organization remains the same for all the computer systems.In 1950s it took a room full of vacuum tubes and equipment to perform the tasks that are now replaced with a single chip, not bigger than a child's thumb nail.

ArchitectureThe basic architecture of a computer system consist of .

The input unitCentral processing unit Output unit

Architecture

Input unitComputers must need the data and instructions in order to solve any problem. Therefore, we need to put the data and instructions into the computers .The input unit consists of one or more input devices.The keyboard of the computer is one of the type of input devices used in the computer system.Functions of input unitAccept data and instruction from the outside world.Convert it to a form that the computer can understand.Supply the converted data to the computer system for further processing.

Input may be pressing a key in the keyboard or moving of the mouse.Central processing unitIt is the heart of the computer system.ie all operations are carried out in this unit only.

It performs all calculationsIt takes all decisionsIt controls all units of the computer

Central processing unitThe CPU can be subdivided into the following four sub-system.

1)Control unit2)Arithmetic logic unit 3)Memory unit4)Secondary Storage

Control unitThe control unit instruct the computer how to carry out a program instruction. It controls and co-ordinates the entire computer system.The input unit does not know when to receive data and where to put the data in the storage unit after receiving it.The control unit gives the necessary instructions to the input device Control unitThe control unit instructs the input unit where to store the data after receiving it from the user.In the same way, it controls the flow of data and instructions from the storage unit to ALU.It also controls the flow of the results from ALU to the storage unit.The control unit also controls what should be sent to the output unit.Arithmetic and logical unitArithmetic logic unit performs all the arithmetic and logical operations.Arithematic operations like Addition,Substraction,Multiplication and Logical operations such as comparison are performed by ALU.

Whenever any calculation has to be done, the control unit transfers the required data from the storage unit to ALU.

Memory unitMemory is part of a computer which holds data for processing and other information. It is called main memory.

The information given from the input unit is immediately stored in the main memory.

It is a Temporary Storage (volatile ) i.e. when the power is OFF, the stored information in the main memory is lost, to avoid this situation ,we can store immediately in secondary memory.

Secondary memoryThe secondary memory is used like an archive. It may store several programs,documents,databases etc.The program that you want to run on the computer is first transferred to the primary memory before it can run.Similarly, after running the program, if u need to save the results ,you will transfer them to secondary memory.The secondary memory is slower and cheaper than the primary memory.It is non volatile.Output unitDevices used to get the response or result of a process from the computer is called output. The output unit of a computer provides the information and results of a computation to the outside world.Printer display screen are commonly used output devices.Components of a computerHardware

CPUPeripherals

Software

System SoftwareApplication software

HARDWAREcpu componentsMotherboardAll the electronic components in a PC are mounted on a Printed Circuit Board(PCB),called the motherboard.

Processor

The microprocessor or the central processing Unit is the computers most important component.

HARDWAREcpu componentsRAM chips

When a computer is switched on and is running a program(RAM ) is used to hold the program and its data. But when the computer is switched off, anything in RAM is lost.

Hard disk driveIt is our computers main permanent storage units, holding large amounts of data and storage.

Types of memory and devicesMemory can be classified into

Primary or main memorySecondary Memory

Primary memoryIn all computers semi-conductors are used for primary memory storage. It is divided into two portions

RAMROM

Read Only Memory

It is inbuilt in the computer at the time of its production.ROM is otherwise called firmware also. It stores a set of instructions permanently which instructs the computers how to work.PROMEPROMRandom access memoryThis is apart of computers local memory where the computer stores all the data and instructions it receives from the input and the results as it works through the calculations.The RAM requires very littlie time for access to each data and is considered to be the fastest memory.ROM It is non-volatile memoryThe contents are permanentCost effectiveAvailable in high storage capacityProcessing speed is low

It is a volatile memoryThe contents are temporaryCost is very highAvailable in smaller capacityProcessing speed is high

RAM Secondary memoryFloppy disk

Magnetic tapes

Hard Disk

CD-ROM

Cache memory

A small memory between CPU and main memory is called cache memory.

.CPUCACHE MEMORYPrimary memorySecondary memoryCache MemoryAdvantages

It stores the current information Reduces the access timeIncreases the performanceIncreases the speed of CPUFast accessing