Chapter One | Computer Science – Detailed Note | HSEB Notes



&   Characteristics/Features of Computer

o   Speed

®     Present computers are capable of processing at an extremply high speed.

o   Accuracy

®     Computer is 100% accurate. It always provides accurate output when the inputs are accurate. It can also be defined by the term GIGO (Garbage in Garbage Out) which means wrong input provides wrong output.

o   Reliability

®     It is reliable devicec as it produces accurate output for accurate inputs.

o   Storage Capacity

®     Present computers are capable of storing huge amount of data permantly.

o   Word Length

®     Word Length refers to number of buts which can be executable at a time. For eg. Word length 8 refers that the computer can process 8 bit data at a time. Present computers have the word length of 32 or 64 and super computer have 128.

o   Deligence

®     Computers never get tired or bored when same task is repeated for multiple times. Efficiency, time of calculation, accuricy will always remain constant.

o   Versatile

®     Computer is a versatile device. It can be used in different areas for different task with minimum changes.

o   Automatic

®     Computer is an automatic device, it can work automatically after the required data and instructions are provided by the user.

o   Electronic

®     Computer is an electric device. It is made by the electric device like IC, Transistors, etc. It requires electrical power supply for it’s operation.

o   Non-intelligent

®     Present computers are non-intelligent. They don’t have learning, thinking, resoning and reacting capacity. It can perform task according to the instruction provided by the user and not by itself.

·         &    Application Areas of Computer
o   Education

®     A new subject

®     Finding study materials

®     Prepare documents, reports

®     Use of simulatoes

o   Communication

®     Internet, e-mail, television, telephone, mobile phones

®     It has made communication faster, easier & cheaper

o   Business

®     Managing financial transaction

®     Security

®     Stock management

®     E-commerce

o   Transportation

®     Ticketing

®     Controllig automated vehicles using auto-pilot system

o   Banking

®     Computerized banking system has made banking process faster and easier

®     Use of ABBS, ATM, Credit Card, internet banking, SMS banking, mobile banking

®     Money transfer service

o   Helth     


o   Security 
o   Industry
o   Scientific Research
o   Entertainment 


o   Weather Forcasting
o   Desktop Publishing
o   Designing
o   Satellite Controlling
o   Aviation
·         &   Capabilities of Computer
                                 i.            It is capable of performing calculations at an extremly high speed

                               ii.            It is capable of generating accurate result when the inputs are accurate

                              iii.            It is capable of storing huge amount of data permantly

                             iv.            It is capable of performing different types of task in different areas with minimum changes

                               v.            It is capable of performing same task for multiple times with same accuricy and in same processing time

                             vi.            It is capable of performing task automatically after required instruction and data are provided

·         &   Limitations of Computer
                                 i.            It cannot operate without electricity

                               ii.            It cannot perform any task by itself

                              iii.            It cannot learn, think, reason or react like humans

·         &   Advantages of Computer
                                 i.            It is always accurate and reliable than humans

                               ii.            They are the fastest device and hence saving our time and money

                              iii.            It is deligence device

                             iv.            It can be used for communication among many users

                               v.            It is versatile i.e. it can be used in many fields with minimum changes

·         &   Disadvantages of Computer
                                 i.            It has been used for cyber crimes like hacking, creating & spreading viruses, etc.

                               ii.            It is machine dependent

                              iii.            Repair and maintenance is required frequently

                             iv.            It is still unaffordable to every household due to it’s high cost

                               v.            Skilled mainpower is must to work in computer

&       History of Computer

                                 i.            Mechanical Age

®     Abacus

®     Stepped Reckoner (Leibniz Calculator)

®     Napier Bone

®     Diffence Engine

®     Slide Rule

®     Analytical Engine

®     Pascaline

®     Tabulating Machine

                               ii.            Electro Mechanical Age

®     MARK-I [Also known as ASCC (Automated Sequence Controlled Calculator)

®     MARK-II

®     ABC (Atanasoft Berry Computer)

                              iii.            Electric Age

®     ENIAC

®     EDAC

®     EDVAC

®     UNIVAC

&      Some Important Persons

                                 i.            Joseph Jaquard

                               ii.            Charles Babbage

                              iii.            George Boole

                             iv.            Herman Hollerith

                               v.            Lady Augusta Ada Lovelace

·         &   Generation of Computer

1st Generation

2nd Generation

3rd Generation

4th Generation

5th Generation

Technology Used

Vaccum Tube




Bio Chip

Operating Speed






Programming Language

Manching Level

Assembly Level

High Level



Primary Memory

Magnetic Core

Magnetic Core

Magnetic tape, Magnetic disk

Magnetic and Optical disk


Secondary Memory

Magnetic tape, Magnetic drum

Magnetic tape, Magnetic drum

Magnetic tape, Magnetic disk

Magnetic tape, Magnetic disk

Input Device

Punched card

Punched card


Advanced I/O like Mouse,scanner

Output Devics

Printing Device

Printing Device


Advanced I/O like LCD, LED, Color Printer


Very High



Very Low


Very less




·        &   Artificial Intelligence (AI)
o   Characteristics of AI

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