Introduction to Computer

Parts of computer

Hardware consists of the mechanical parts that make up the computer as a machine. The hardware consists of physical devices of the computer. The devices are required for input, output, storage and processing of the data. Keyboard, monitor, hard disk drive, floppy disk drive, printer, processor and motherboard are some of the hardware devices.

Software is a set of instructions that tells the computer about the tasks to be performed and how these tasks are to be performed. Program is a set of instructions, written in a language understood by the computer, to perform a specific task. A set of programs and documents are collectively called software. The hardware of the computer system cannot perform any task on its own. The hardware needs to be instructed about the task to be performed. Software instructs the computer about the task to be performed. The hardware carries out these tasks. Different software can be loaded on the same hardware to perform different kinds of tasks.

Data are isolated values or raw facts, which by themselves have no much significance. For example, the data like 29, January, and 1994 just represent values. The data is provided as input to the computer, which is processed to generate some meaningful information. For example, 29, January and 1994 are processed by the computer to give the date of birth of a person.

Users are people who write computer programs or interact with the computer. They are also known as skinware, liveware, humanware or peopleware. Programmers, data entry operators, system analyst and computer hardware engineers fall into this category.

 Input devices

Following are few of the important input devices, which are used in Computer Systems:

·       Keyboard

·       Mouse

·       Joystick

·       Light pen

·       Track Ball

·       Scanner

·       Graphic Tablet

·       Microphone

·       Magnetic Ink Card Reader (MICR)

·       Optical Character Reader (OCR)

·       Bar Code Reader

·       Optical Mark Reader

Output devices:

Following are few of the important output devices, which are used in Computer Systems:

• Monitors

• Graphic Plotter

• Printer

Monitors

Monitor commonly called as Visual Display Unit (VDU) is the main output device of a computer. It forms images from tiny dots, called pixels, that are arranged in a rectangular form. The sharpness of the image depends upon the number of the pixels.

There are two kinds of viewing screen used for monitors:

• Cathode-Ray Tube (CRT)

·       Large in Size

·       High power consumption

• Flat-Panel Display

• have reduced volume, weight and power requirement compared to the CRT. You can hang them on walls or wear them on your wrists. Current uses for flat-panel displays include calculators, video games, monitors, laptop computer, graphics display.

Printers

Printer is the most important output device, which is used to print information on paper.

There are two types of printers:

·       Impact Printers

·       Non-Impact Printers

Impact Printers

The printers that print the characters by striking against the ribbon and onto the paper, are called impact printers.

Characteristics of Impact Printers are the following:

·       Very low consumable costs

·       Impact printers are very noisy

Non-impact Printers

The printers that print the characters without striking against the ribbon and onto the paper are called Non-impact Printers. These printers print a complete page at a time, also called as Page Printers.

These printers are of two types:

·       Laser Printers

·       Inkjet Printers

Characteristics of Non-impact Printers:

·       Faster than impact printers.

·       They are not noisy.

A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in computer where data is to be processed and instructions required for processing are stored.

The memory is divided into large number of small parts. Each part is called cell. Each location or cell has a unique address, which varies from zero to memory size minus one.

For example, if computer has 64k words, then this memory unit has 64 * 1024=65536 memory location. The address of these locations varies from 0 to 65535.

Memory is primarily of three types:

·       Cache Memory

·       Primary Memory/Main Memory

·       Secondary Memory

Cache Memory:

Cache memory is a very high speed semiconductor memory, which can speed up CPU. It acts as a buffer between the CPU and main memory.

It is used to hold those parts of data and program which are most frequently used by CPU. The parts of data and programs are transferred from disk to cache memory by operating system, from where CPU can access them.

Advantage

·       Cache memory is faster than main memory.

·       It consumes less access time as compared to main memory.

·       It stores the program that can be executed within a short period of time.

·       It stores data for temporary use.

Disadvantage:

·       Cache memory has limited capacity.

·       It is very expensive.

Primary Memory (Main Memory):

Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data gets lost when power is switched off.

It is generally made up of semiconductor device. These memories are not as fast as registers. The data and instructions required to be processed earlier reside in main memory. It is divided into two subcategories RAM and ROM.

Characteristic of Main Memory:

·       These are semiconductor memories.

·       It is known as main memory.

·       Usually volatile memory.

·       Data is lost in case power is switched off.

·       It is working memory of the computer.

·       Faster than secondary memories.

·       A computer cannot run without primary memory.

Secondary Memory:

This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing Data/Information permanently.

CPU directly does not access these memories, instead they are accessed via input-output routines. Contents of secondary memories are first transferred to main memory and then CPU can access it. For example, disk, CD-ROM, DVD, etc.

Characteristics of Secondary Memory:

·       These are magnetic and optical memories.

·       It is known as backup memory.

·       It is non-volatile memory.

·       Data is permanently stored even if power is switched off.

·       It is used for storage of the data in the computer.

·       Computer may run without secondary memory.

·       Slower than primary memories.

RAM:

RAM constitutes the internal memory of the CPU for storing data, program and program result. It is read/write memory. It is called random access memory (RAM).

RAM is of two types:

·       Static RAM (SRAM)

·       Dynamic RAM (DRAM

Characteristics of the Static RAM:

·       It has long data lifetime

·       There is no need to refresh

·       Faster

·       Used as cache memory

·       Large size

·       Expensive

·       High power consumption

Characteristics of the Dynamic RAM:

·       It has short data lifetime

·       Need to refresh continuously

·       Slower as compared to SRAM

·       Used as RAM

·       Lesser in size

·       Less expensive

·       Less power consumption

Hardware:

Hardware represents the physical and tangible components of the computer, i.e., the components that can be seen and touched.

Examples of Hardware are following:

·       Input devices -- keyboard, mouse, etc.

·       Output devices -- printer, monitor, etc.

·       Secondary storage devices -- Hard disk, CD, DVD, etc.

·       Internal components -- CPU, motherboard, RAM, etc.

Software is a set of programs, which are designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem.

There are two types of softwares:

·       System Software

·       Application Software

Some examples of system software are Operating System, Compilers, Interpreter, Assemblers, etc

Features of System Software are the following:

·       Close to system.

·       Fast in speed.

·       Difficult to design.

·       Difficult to understand.

·       Less interactive.

·       Smaller in size.

·       Difficult to manipulate.

·       Generally written in low-level language.

Application Software:

Application softwares are the softwares that are designed to satisfy a particular need of a particular environment.

Examples of Application softwares are the following:

·       Payroll Software

·       Student Record Software

·       Inventory Management Software

·       Income Tax Software

·       Railways Reservation Software

·       Microsoft Office Suite Software

·       Microsoft Word

·       Microsoft Excel

·       Microsoft Powerpoint

Features of Application Software are the following:

·       It is close to user.

·       It is easy to design.

·       More interactive.

·       Slow in speed.

·       Generally written in high-level language.

·       Easy to understand.

·       Easy to manipulate and use.

·       Bigger in size and requires large storage space.

CPU

·       CPU is considered as the brain of the computer.

·       CPU performs all types of data processing operations.

·       It stores data, intermediate result and instructions (program).

·       It controls the operations of all parts of computer.

CPU itself has the following three components.

·       Memory or Storage Unit:

·       Control Unit

·       ALU (Arithmetic Logic Unit)

 Uses of Computer:

Business

The computer's characteristic as high speed of calculation, diligence, accuracy, reliability, or versatility has made it an integrated part in all business organisations.

Computer is used in business organisation for:

·       Payroll Calculations

·       Budgeting

·       Sales Analysis

·       Financial forecasting

·       Managing employees database

·       Maintenance of stocks, etc.

Banking: Today Banking is almost totally dependent on computer.

Banks provide following facilities:

·       Banks on-line accounting facility, which includes current balances, deposits, overdrafts, interest charges, shares and trustee records.

·       ATM machines are making it even easier for customers to deal with banks.

Education: The computer has provided a lot of facilities in the Education System.

·       The uses of computer provide a tool in the Education system known as CBE (Computer Based Education).

Marketing: In Marketing uses of computer are following:

·       Advertising: With computers, advertising professionals create art and graphics, write and revise copy, and print and disseminate ads with the goal of selling more products.

·       At Home Shopping: Home shopping has been made possible through use of computerised catalogues that provide access to product information and permit direct entry of orders to be filled by the customers.

Engineering Design: Military

Computers are largely used in defence. Modern tanks, missiles, weapons, etc., employ computerised control systems. Some military areas where a computer has been used are:

·       Missile Control

·       Military Communication

·       Military operation and planning

·       Smart Weapons