Basics of Computers - Introduction

 

Happy new year!

Basics of Computers - 

Being a modern-day kid you must have used, seen, or read about computers. This is because they are an integral part of our everyday existence. Be it school, banks, shops, railway stations, hospital or your own home, computers are present everywhere, making our work easier and faster for us. As they are such integral parts of our lives, we must know what they are and how they function. Let us start with defining the term computer formally.

The literal meaning of computer is a device that can calculate. However, modern computers can do a lot more than calculate. Computer is an electronic device that receives input, stores or processes the input as per user instructions and provides output in desired format.

Input-Process-Output Model

Computer input is called data and the output obtained after processing it, based on user’s instructions is called information. Raw facts and figures which can be processed using arithmetic and logical operations to obtain information are called data.

Workflow

The processes that can be applied to data are of two types −

Arithmetic operations − Examples include calculations like addition, subtraction, differentials, square root, etc.

Logical operations − Examples include comparison operations like greater than, less than, equal to, opposite, etc.

The corresponding figure for an actual computer looks something like this −

Block Diagram

The basic parts of a computer are as follows −

Input Unit − Devices like keyboard and mouse that are used to input data and instructions to the computer are called input unit.

Output Unit − Devices like printer and visual display unit that are used to provide information to the user in desired format are called output unit.

Control Unit − As the name suggests, this unit controls all the functions of the computer. All devices or parts of computer interact through the control unit.

Arithmetic Logic Unit − This is the brain of the computer where all arithmetic operations and logical operations take place.

Memory − All input data, instructions and data interim to the processes are stored in the memory. Memory is of two types – primary memory and secondary memory. Primary memory resides within the CPU whereas secondary memory is external to it.

Control unit, arithmetic logic unit and memory are together called the central processing unit or CPU. Computer devices like keyboard, mouse, printer, etc. that we can see and touch are the hardware components of a computer. The set of instructions or programs that make the computer function using these hardware parts are called software. We cannot see or touch software. Both hardware and software are necessary for working of a computer.

Characteristics of Computer

To understand why computers are such an important part of our lives, let us look at some of its characteristics −

Speed − Typically, a computer can carry out 3-4 million instructions per second.

Accuracy − Computers exhibit a very high degree of accuracy. Errors that may occur are usually due to inaccurate data, wrong instructions or bug in chips – all human errors.

Reliability − Computers can carry out same type of work repeatedly without throwing up errors due to tiredness or boredom, which are very common among humans.

Versatility − Computers can carry out a wide range of work from data entry and ticket booking to complex mathematical calculations and continuous astronomical observations. If you can input the necessary data with correct instructions, computer will do the processing.

Storage Capacity − Computers can store a very large amount of data at a fraction of cost of traditional storage of files. Also, data is safe from normal wear and tear associated with paper.

Advantages of Using Computer

Now that we know the characteristics of computers, we can see the advantages that computers offer−

Computers can do the same task repetitively with same accuracy.

Computers do not get tired or bored.

Computers can take up routine tasks while releasing human resource for more intelligent functions.

Disadvantages of Using Computer

Despite so many advantages, computers have some disadvantages of their own −

Computers have no intelligence; they follow the instructions blindly without considering the outcome.

Regular electric supply is necessary to make computers work, which could prove difficult everywhere especially in developing nations.

Booting

Starting a computer or a computer-embedded device is called booting. Booting takes place in two steps −

Switching on power supply

Loading operating system into computer’s main memory

Keeping all applications in a state of readiness in case needed by the user

The first program or set of instructions that run when the computer is switched on is called BIOS or Basic Input Output System. BIOS is a firmware, i.e. a piece of software permanently programmed into the hardware.

If a system is already running but needs to be restarted, it is called rebooting. Rebooting may be required if a software or hardware has been installed or system is unusually slow.

There are two types of booting −

Cold Booting − When the system is started by switching on the power supply it is called cold booting. The next step in cold booting is loading of BIOS.

Warm Booting − When the system is already running and needs to be restarted or rebooted, it is called warm booting. Warm booting is faster than cold booting because BIOS is not reloaded.

Introduction to Computer

Computer

A computer is an electronic device, operating under the control of instructions stored

in its own memory that can accept data (input), process the data according to specified

rules, produce information (output), and store the information for future use1.

Functionalities of a computer2

Any digital computer carries out five functions in gross terms:

Computer Components

Any kind of computers consists of HARDWARE AND SOFTWARE.

Hardware:

Computer hardware is the collection of physical elements that constitutes a computer

system. Computer hardware refers to the physical parts or components of a computer

such as the monitor, mouse, keyboard, computer data storage, hard drive disk (HDD),

system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of

which are physical objects that can be touched.Input Devices

Input device is any peripheral (piece of computer hardware equipment to provide data

and control signals to an information processing system such as a computer or other

information appliance.

Input device Translate data from form that humans understand to one that the computer

can work with. Most common are keyboard and mouse

Example of Input Devices:-

1. Keyboard

2. Mouse (pointing device)

3. Microphone

4. Touch screen

5. Scanner

6. Webcam

7. Touchpads

8. MIDI keyboard

9.

10.Graphics Tablets

11.Cameras

12.Pen Input

13.Video Capture Hardware

14.Microphone

15.Trackballs

16.Barcode reader

17.Digital camera

18.Joystick

19.Gamepad

20.Electronic Whiteboard

21.

Note: The most common use keyboard is the QWERTY keyboard. Generally standard Keyboard has 104 keysCentral Processing Unit (CPU)

A CPU is brain of a computer. It is responsible for all functions and processes.

Regarding computing power, the CPU is the most important element of a computer

system.

The CPU is comprised of three main parts :

* Arithmetic Logic Unit (ALU): Executes all arithmetic and logical operations.

Arithmetic calculations like as addition, subtraction, multiplication and division.

Logical operation like compare numbers, letters, or special characters

* Control Unit (CU): controls and co-ordinates computer components.

1. Read the code for the next instruction to be executed.

2. Increment the program counter so it points to the next instruction.

3. Read whatever data the instruction requires from cells in memory.

4. Provide the necessary data to an ALU or register.

5. If the instruction requires an ALU or specialized hardware to complete, instruct

the hardware to perform the requested operation.

* Registers :Stores the data that is to be executed next, "very fast storage area".

Primary Memory:-

1. RAM: Random Access Memory (RAM) is a memory scheme within the computer

system responsible for storing data on a temporary basis, so that it can be promptly

accessed by the processor as and when needed. It is volatile in nature, which means

that data will be erased once supply to the storage device is turned off. RAM stores

data randomly and the processor accesses these data randomly from the RAM

storage. RAM is considered "random access" because you can access any memory

cell directly if you know the row and column that intersect at that cell.

2. ROM (Read Only Memory): ROM is a permanent form of storage. ROM stays

active regardless of whether power supply to it is turned on or off. ROM devices

do not allow data stored on them to be modified.

Secondary Memory:-

Stores data and programs permanently :its retained after the power is turned off

1. Hard drive (HD): A hard disk is part of a unit, often called a "disk drive," "hard drive," or "hard

disk drive," that store and provides relatively quick access to large amounts of data on an

electromagnetically charged surface or set of surfaces.

2. Optical Disk: an optical disc drive (ODD) is a disk drive that uses laser light as part of the process

of reading or writing data to or from optical discs. Some drives can only read from discs, but recent

drives are commonly both readers and recorders, also called burners or writers. Compact discs,

DVDs, and Blu-ray discs are common types of optical media which can be read and recorded by

such drives. Optical drive is the generic name; drives are usually described as "CD" "DVD", or

"Bluray", followed by "drive", "writer", etc. There are three main types of optical media: CD,

DVD, and Blu-ray disc. CDs can store up to 700 megabytes (MB) of data and DVDs can store up

to 8.4 GB of data. Blu-ray discs, which are the newest type of optical media, can store up to 50

GB of data. This storage capacity is a clear advantage over the floppy disk storage media (a magnetic media), which only has a capacity of 1.44 MB3. Flash Disk

A storage module made of flash memory chips. A Flash disks have no mechanical platters or access

arms, but the term "disk" is used because the data are accessed as if they were on a hard drive. The

disk storage structure is emulated.

Output devices

An output device is any piece of computer hardware equipment used to communicate

the results of data processing carried out by an information processing system (such

as a computer) which converts the electronically generated information into humanreadable form.

Example on Output Devices:

1. Monitor

2. LCD Projection Panels

3. Printers (all types)

4. Computer Output Microfilm (COM)

5. Plotters

6. Speaker(s)

7. Projector

Note Basic types of monitors are a.Cathode Ray Tube (CRT). B. Liquid Crystal Displays (LCD). c.light-emitting diode (LED).

Printer types: 1-Laser Printer. 2-Ink Jet Printer. 3-Dot Matrix PrinterSoftware

Software is a generic term for organized collections of computer data and instructions,

often broken into two major categories: system software that provides the basic nontask-specific functions of the computer, and application software which is used by

users to accomplish specific tasks.

Software Types

A. System software is responsible for controlling, integrating, and managing the

individual hardware components of a computer system so that other software and

the users of the system see it as a functional unit without having to be concerned

with the low-level details such as transferring data from memory to disk, or

rendering text onto a display. Generally, system software consists of an operating

system and some fundamental utilities such as disk formatters, file managers,

display managers, text editors, user authentication (login) and management tools,

and networking and device control software.

B. Application software is used to accomplish specific tasks other than just running

the computer system. Application software may consist of a single program, such

as an image viewer; a small collection of programs (often called a software

package) that work closely together to accomplish a task, such as a spreadsheet or

text processing system; a larger collection (often called a software suite) of related

but independent programs and packages that have a common user interface or

shared data format, such as Microsoft Office, which consists of closely integrated

word processor, spreadsheet, database, etc.; or a software system, such as a

database management system, which is a collection of fundamental programs that

may provide some service to a variety of other independent applications.

Comparison Application Software and System Software

System Software

Application Software

Computer software, or just software is a

general term primarily used for digitally stored

data such as computer programs and other

kinds of information read and written by

computers. App comes under computer

software though it has a wide scope now.

Application software, also known as an

application or an "app", is computer software

designed to help the user to perform specific

tasks.

Example:

1) Microsoft Windows

2) Linux

3) Unix

4) Mac OSX

5) DOS

1) Opera (Web Browser)

2) Microsoft Word (Word Processing)

3) Microsoft Excel (Spreadsheet software)

4) MySQL (Database Software)

5) Microsoft PowerPoint (Presentation Software)

6) Adobe Photoshop (Graphics Software)

Interaction:

Generally, users do not interact with system

software as it works in the background.

Users always interact with application software

while doing different activities.

Dependency:

System software can run independently of the

application software.

Application software cannot run without the

presence of the system software.Unit of Measurements

Storage measurements: The basic unit used in computer data storage is called a bit

(binary digit). Computers use these little bits, which are composed of ones

and zeros, to do things and talk to other computers. All your files, for

instance, are kept in the computer as binary files and translated into words

and pictures by the software (which is also ones and zeros). This two

number system, is called a “binary number system” since it has only two

numbers in it. The decimal number system in contrast has ten unique digits,

zero through nine.

Computer Storage units

Bit

BIT

0 or 1

Kilobyte

KB

1024 bytes

Megabyte

MB

1024 kilobytes

Gigabyte

GB

1024 megabytes

Terabyte

TB

1024 gigabytes

Size example

• 1 bit - answer to an yes/no question

• 1 byte - a number from 0 to 255.

• 90 bytes: enough to store a typical line of text from a book.

• 4 KB: about one page of text.

• 120 KB: the text of a typical pocket book.

• 3 MB - a three minute song (128k bitrate)

• 650-900 MB - an CD-ROM

• 1 GB -114 minutes of uncompressed CD-quality audio at 1.4 Mbit/s

• 8-16 GB - size of a normal flash drive

Speed measurement: The speed of Central Processing Unit (CPU) is measured by

Hertz (Hz), Which represent a CPU cycle. The speed of CPU is known as Computer

Speed.

CPU SPEED MEASURES

1 hertz or Hz

1 cycle per second

1 MHz

1 million cycles per second or 1000 Hz

1 GHz

1 billion cycles per second or 1000 MHzComputers classification***

Computers can be generally classified by size and power as follows, though there is

Considerable overlap:

• Personal computer: A small, single-user computer based on a microprocessor. In

addition to the microprocessor, a personal computer has a keyboard for entering

data, a monitor for displaying information, and a storage device for saving data.

• workstation : A powerful, single-user computer. A workstation is like a personal

computer, but it has a more powerful microprocessor and a higher-quality

monitor.

• minicomputer : A multi-user computer capable of supporting from 10 to hundreds of

users simultaneously.

• mainframe : A powerful multi-user computer capable of supporting many hundreds

or thousands of users simultaneously.

• supercomputer : An extremely fast computer that can perform hundreds of millions

of instructions per second.

Laptop and Smartphone Computers

LAPTOP: A laptop is a battery or AC-powered personal computer that can be easily

carried and used in a variety of locations. Many laptops are designed to

have all of the functionality of a desktop computer, whichmeans they can

generally run the same software and open the same types of files. However,

some laptops, such as netbooks, sacrifice some functionality in order to be

even more portable.

Netbook: A netbook is a type of laptop that is designed to be even more portable.

Netbooks are often cheaper than laptops or desktops. They are generally less

powerful than other types of computers, but they provide enough power for

email and internet access, which is where the name "netbook" comes from.

Mobile Device: A mobile device is basically any handheld computer. It is designed to

be extremely portable, often fitting in the palm of your hand or in your pocket.

Some mobile devices are more powerful, and they allow you to do many of the same things you can do with a desktop or laptop computer. These include

tablet computers, e-readers, and smartphones.

Tablet Computers: Like laptops, tablet computers are designed to be portable.

However, they provide a very different computing experience. The most

obvious difference is that tablet computers don't have keyboards or touchpads.

Instead, the entire screen is touch-sensitive, allowing you to type on a virtual

keyboard and use your finger as a mouse pointer. Tablet computers are mostly

designed for consuming media, and they are optimized for tasks like web

browsing, watching videos, reading e-books, and playing games. For many

people, a "regular" computer like a desktop or laptop is still needed in order

to use some programs. However, the convenience of a tablet computer means

that it may be ideal as a second computer.

Smartphones: A smartphone is a powerful mobile phone that is designed to run a

variety of applications in addition to phone service. They are basically small

tablet computers, and they can be used for web browsing, watching videos,

reading e-books, playing games and more.

Data, Information and Knowledge

Data: Facts and figures which relay something specific, but which are not organized

in any way and which provide no further information regarding patterns, context, etc.

So data means "unstructured facts and figures that have the least impact on the typical

manager."

Information: For data to become information, it must be contextualized, categorized,

calculated and condensed. Information thus paints a bigger picture; it is data with

relevance and purpose. It may convey a trend in the environment, or perhaps indicate

a pattern of sales for a given period of time. Essentially information is found "in

answers to questions that begin with such words as who, what, where, when, and how

many".

Knowledge: Knowledge is closely linked to doing and implies know-how and

understanding. The knowledge possessed by each individual is a product of his

experience, and encompasses the norms by which he evaluates new inputs from his surroundings.

The content of the human mind can be classified into four categories:

1. Data: symbols

2. Information: data that are processed to be useful; provides answers to "who", "what",

"where", and "when" questions

3. Knowledge: application of data and information; answers "how" questions

4. Wisdom: evaluated understanding.

We need to understand that processing data produced Information and process

Information produces Knowledge and so on

Characteristics of Computer

Speed, accuracy, diligence, storage capability and versatility are some of the key

characteristics of a computer. A brief overview of these characteristics are

• Speed: The computer can process data very fast, at the rate of millions of instructions

per second. Some calculations that would have taken hours and days to

complete otherwise, can be completed in a few seconds using the computer.

For example, calculation and generation of salary slips of thousands of

employees of an organization, weather forecasting that requires analysis of a

large amount of data related to temperature, pressure and humidity of various

places, etc.

• Accuracy: Computer provides a high degree of accuracy. For example, the computer

can accurately give the result of division of any two numbers up to 10 decimal

places.

• Diligence: When used for a longer period of time, the computer does not get tired or

fatigued. It can perform long and complex calculations with the same speed and

accuracy from the start till the end.

• Storage Capability: Large volumes of data and information can be stored in the

computer and also retrieved whenever required. A limited amount of data can

be stored, temporarily, in the primary memory. Secondary storage devices like

floppy disk and compact disk can store a large amount of data permanently.

• Versatility: Computer is versatile in nature. It can perform different types of tasks

with the same ease. At one moment you can use the computer to prepare a letter

document and in the next moment you may play music or print a document.

Computers have several limitations too. Computer can only perform tasks that it has been programmed to do. 

Computer cannot do any work without instructions from the user. It executes

instructions as specified by the user and does not take its own decisions.

Computer Viruses*

Viruses: A virus is a small piece of software that piggybacks on real programs. For

example, a virus might attach itself to a program such as a spreadsheet program.

Each time the spreadsheet program runs, the virus runs, too, and it has the

chance to reproduce (by attaching to other programs) or wreak havoc.

•E-mail viruses: An e-mail virus travels as an attachment to e-mail messages, and

usually replicates itself by automatically mailing itself to dozens of people

in the victim's e-mail address book. Some e-mail viruses don't even require

a double-click -- they launch when you view the infected message in the

preview pane of your e-mail software [source: Johnson].

•Trojan horses: A Trojan horse is simply a computer program. The program claims to

do one thing (it may claim to be a game) but instead does damage when you

run it (it may erase your hard disk). Trojan horses have no way to replicate

automatically.

•Worms: A worm is a small piece of software that uses computer networks and security

holes to replicate itself. A copy of the worm scans the network for another

machine that has a specific security hole. It copies itself to the new machine

using the security hole, and then starts replicating from there, as well.

What are some tips to avoid viruses and lessen their impact?*

 Install anti-virus software from a reputable vendor. Update it and use it

regularly.

 In addition to scanning for viruses on a regular basis, install an "on access"

scanner (included in most anti-virus software packages) and configure it to start

each time you start up your computer. This will protect your system by

checking for viruses each time you run an executable file.

 Use a virus scan before you open any new programs or files that may contain

executable code. This includes packaged software that you buy from the store

as well as any program you might download from the Internet.

 If you are a member of an online community or chat room, be very careful

about accepting files or clicking links that you find or that people send you

within the community.

 Make sure you back up your data (documents, bookmark files, important email

messages, etc.) on disc so that in the event of a virus infection, you do not lose

valuable work.