classXI-C

Computer Science

Unit

Computer Science

Unit-1

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This presentation covers the following topics:

• Computer Fundamentals• Evolution of Computers• Strengths and Weaknesses of a Computer.

This presentation covers the following topics:

Computer FundamentalsEvolution of ComputersStrengths and Weaknesses of a Computer.




Part

Computer Fundamentals

Part-I

Computer Fundamentals




What is a “computer

• The word computer basically originated from the word “compute” which meanscalculate”.

• So a computer was normally considered to be a device that can “perform calculations”“arithmetic operations”

computer”?

The word computer basically originated from which means “to

So a computer was normally considered to be “perform calculations”- i.e.

“arithmetic operations” at “enormous speed”.




• Yes, the original objective of inventing a computer was – to create a fast calculating machine.

• But, today more than 80% of the work done by computer is of non mathematical or non numeric in nature.

Yes, the original objective of inventing a to create a fast calculating

But, today more than 80% of the work done by computer is of non mathematical or non




Therefore, a computer may be defined more accurately as:

“an electronic device that can perform variety of operations in accordance with a set of instructions called a program”

Therefore, a computer may be defined more accurately as:

“an electronic device that can perform variety of operations in accordance with a set of instructions called a program”




Data VS Information

• A computer is considered as a • DATA – Data in computer terminology means

raw facts or figures e.g., ‘Mohan’, 1977, ‘A’.• INFORMATION – what we get after processing

data is information. Data is aggregated and summarized in various meaningful ways to form information e.g. ‘Mohan whose roll number is 1977, has got ‘A’ grade.

Data VS Information

A computer is considered as a data processor.Data in computer terminology means

raw facts or figures e.g., ‘Mohan’, 1977, ‘A’.what we get after processing

data is information. Data is aggregated and summarized in various meaningful ways to form information e.g. ‘Mohan whose roll number is 1977, has got ‘A’ grade.




More general terms we can say that:

• Data- is what goes in the computer• Information- is what comes out of the

computer i.e. the output.

More general terms we can say that:

is what goes in the computeris what comes out of the

computer i.e. the output.




Functioning of a Computer

• The basic structure of a computer can be shown as:

Input Unit Central Processing Unit(CPU)

Main Memory

Functioning of a Computer

The basic structure of a computer can be

Central Processing Unit(CPU) Output Unit

Main Memory




Input Unit

• Formed by the input devices attached to the computer e.g. keyboard, mouse, joystick etc.

• Responsible for taking input and converting into computer understandable form(binary codes).

• Therefore defined as “ An input unit takes the input and converts it into binary form so that it can be understood by the computer”.

Input Unit

Formed by the input devices attached to the computer e.g. keyboard, mouse, joystick etc.Responsible for taking input and converting into computer understandable form(binary

“ An input unit takes the input and converts it into binary form so that it can be understood by the computer”.




Central Processing Unit

• Control center of the computer.• Considered to be the brain of the computer as

it guides, directs and governs its performance.• It has two components:

1. Arithmetic Logic Unit( ALU)2. Control Unit

Central Processing Unit

Control center of the computer.Considered to be the brain of the computer as it guides, directs and governs its performance.It has two components:1. Arithmetic Logic Unit( ALU)




Arithmetic Logic Unit

• Performs all four arithmetic (+, logical ( <, >, =, <=, >=, <>) operations.

• Suppose two numbers are to be added, these numbers are sent from the memory to ALU where addition takes place and the result is put back in the memory.

Arithmetic Logic Unit

Performs all four arithmetic (+, -, *,/) and logical ( <, >, =, <=, >=, <>) operations.Suppose two numbers are to be added, these numbers are sent from the memory to ALU where addition takes place and the result is put back in the memory.




Control Unit

• Controls and guides theand manipulation of all data and information.

• It sends control signals until the required operations are done properly by ALU and memory.

• Performs program execution i.e. carrying out all the instructions stored in the program.

Control Unit

the interpretation , flowof all data and information.

It sends control signals until the required operations are done properly by ALU and

Performs program execution i.e. carrying out all the instructions stored in the program.




Control Unit contd..

• It gets program instruction from the memory and executes them one after the other.

• The instruction is then decoded and interpreted i.e. which operation to be performed.

• After the work of particular instruction is completed, CU sends signal to memory to send the next instruction in sequence.


It gets program instruction from the memory and executes them one after the other.The instruction is then decoded and interpreted i.e. which operation to be

After the work of particular instruction is completed, CU sends signal to memory to send the next instruction in sequence.





Therefore a Control Unit even controls the flow of data :1. from input devices to memory2. and from memory to output devices.


Therefore a Control Unit even controls the flow

from input devices to memorynd from memory to output devices.




Output Unit

• Formed by output devices attached to the computer e.g. monitor, printer, plotter etc.

• Output comes from CPU in the form of binary signals which needs to be converted into human understandable form i.e. texts, graphics, images etc.

• This conversion is performed by output units.

Output Unit

Formed by output devices attached to the computer e.g. monitor, printer, plotter etc.Output comes from CPU in the form of binary signals which needs to be converted into human understandable form i.e. texts,

This conversion is performed by output units.




The Memory

• The memory of a computer is often called main memory or primary memory . It is generally the third component of the computer.

• Unlike human memory which can remember stored information for a very long time, a computer’s memory is volatile remember anything after it is switched off.

The Memory

The memory of a computer is often called main memory or primary memory . It is generally the third component of the

Unlike human memory which can remember stored information for a very long time, a computer’s memory is volatile i.e. it cannot remember anything after it is switched off.




Memory contd..

• A memory of a computer can be thought of as ‘cells’.

• A memory cell may be defined as a device that can store a symbol selected from a set of symbols.

• Each of these cells is further broken down into smaller parts known as ‘

Memory contd..

A memory of a computer can be thought of as

A memory cell may be defined as a device that can store a symbol selected from a set of

Each of these cells is further broken down into smaller parts known as ‘bits’.




Memory contd..

• A bit means a binary digit i.e. either 0 or 1.

A bit is an elementary unit of memory.

1 0 0 1 1

Memory contd..

A bit means a binary digit i.e. either 0 or 1.

A bit is an elementary unit of memory.

0 0 1 Cell 0

Cell 1

Bit




Memory contd..

• A number of bits together are used to store data instructions by their combinations.

• Group of 8 bits – BYTE• Group of 4 bits – NIBBLE.• One byte is the smallest unit which can

represent a data item or character.• Other units are KB, MB, GB, TB.

Memory contd..

A number of bits together are used to store data instructions by their combinations.

NIBBLE.One byte is the smallest unit which can represent a data item or character.Other units are KB, MB, GB, TB.




Memory contd..

• One KB(Kilobyte) = 210

• One MB(Megabyte) = 2bytes.

• One GB(Gigabyte) = 210

= 1024*1024*1024 bytes.One TB(Terabyte) = 210

One PB( Petabyte) = 210

Memory contd..10 bytes = 1024 bytes.

One MB(Megabyte) = 210 KB = 1024 * 1024

10 MB = 1024*1024*1024 bytes.

10 GB = 1024 GB10 TB = 1024 TB.




Hardware and Software

Obviously a computer needs hardware and software for proper functioning.

Hardware- represents the physical and tangible components of the computer i.e. the components that can be seen and touched.Software- set of programs that govern the operation of a computer system and make the hardware run.

Hardware and Software

Obviously a computer needs hardware and software for proper functioning.

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

set of programs that govern the operation of a computer system and make the




Hardware

• The electronic, electrical and mechanical equipment that makes a computer is called hardware.

• Input devices, output devices, CPU, floppy disk, hard disk etc.

• Also known as peripherals devices that surround the system.

Hardware

The electronic, electrical and mechanical equipment that makes a computer is called

Input devices, output devices, CPU, floppy

peripherals which means the devices that surround the system.




A computer consists of the 5 primary hardware components:

• Input devices• Output devices• CPU• Storage Devices• Memory

A computer consists of the 5 primary hardware components:




Software

Classified broadly into 2 categories :1. System Software- controls the internal

computer operations.2. Application Software

necessary to carry out operations for a specified application.

Software

Classified broadly into 2 categories :controls the internal

Application Software- set of programs necessary to carry out operations for a specified




System Software

• Computer requires instructions for each and everything it performs

• These instructions are provided through a software

• The software that controls internal computer operations(reading data from input devices, transmitting processed information to the output device) is known as system software.

System Software

Computer requires instructions for each and

These instructions are provided through a

The software that controls internal computer operations(reading data from input devices, transmitting processed information to the output device) is known as system software.




System Software can be further classified into two categories:

• Operating System – is a program which acts as an interface between the user and the hardware.

• Language Processors –language (programming instructions) into machine language.

System Software can be further classified into two categories:

is a program which acts as an interface between the user and the

– converts high level language (programming instructions) into




Operating system

• A computer is a machine which is made to work.

• It is either ‘we’ who make it work or the ‘operating system’.

• An operating system is an important component of the computer system which controls all other components of the computer system.

Operating system

A computer is a machine which is made to

It is either ‘we’ who make it work or the

An operating system is an important component of the computer system which controls all other components of the




The major components of the computer system are:

• Hardware- provides the basic computing resources.

• Operating system- defines the ways in which these resources are to be utilized.

• Application program routines( compiler, linkers, database management system, utility programs)

• The users.

The major components of the computer system are:

provides the basic computing resources.

defines the ways in which these

Application program routines( compiler, linkers, database management system, utility




Operating system controls and cothe hardware among various application programs for

the various users.Users

Application Software

Operating System

CPU and Hardware

CPU

Interacts with

Interacts with

Interacts with

Operating system controls and co-ordinates the use of the hardware among various application programs for

the various users.

Operating System

Application Software

Users




Functions of the operating system:

• Provides the instructions to prepare user interface i.e. the way to interact with user ( through typed commands or graphical icons.)

• Loads necessary programs(into computer memory) which are required for proper computer functioning.

• Coordinates how computer work with CPU, keyboard, mouse, printer and other hardware as well as software.

• Manages the way information is stored on and retrieved from disks.

Functions of the operating system:

Provides the instructions to prepare user interface i.e. the way to interact with user ( through typed commands or graphical icons.)Loads necessary programs(into computer memory) which are required for proper computer

Coordinates how computer work with CPU, keyboard, mouse, printer and other hardware as

Manages the way information is stored on and




Types of Services of Operating System:

Operating system provides certain services to programs and to the users of the program which are listed below:

• Program Execution- responsible for executing various programs such as system programs which are required for the machine functioning.

• Handling Input/output Operationshandling various types of inputs and various types of outputs in the appropriate manner.

• Manipulation of File Systemdecisions regarding the storage of files i.e. where and how the particular file is to be stored.

Types of Services of Operating System:

Operating system provides certain services to programs and to the users of the program which are listed below:

responsible for executing various programs such as system programs which are required for the machine functioning.Handling Input/output Operations- responsible for handling various types of inputs and various types of outputs in the appropriate manner.Manipulation of File System- involves making of decisions regarding the storage of files i.e. where and how the particular file is to be stored.




• Error Detection and Handlingdetecting any type of error that occurs and then properly handling it.

• Resource Allocation- aims at proper use of resources available e.g. if multiple files are to be printed then how and in which order this task will take place.

• Accounting- keeps and account of what type of functioning is taking place and type of errors have occurred.

• Information and Resource ensuring that the information and resources available on machine are used in the correct way.

Handling- responsible for detecting any type of error that occurs and then

aims at proper use of resources available e.g. if multiple files are to be printed then how and in which order this task will take place.

keeps and account of what type of functioning is taking place and type of errors have

Information and Resource Protection- responsible for ensuring that the information and resources available on machine are used in the correct way.




Operating System Function:

Major OS Functions are listed below:1. Processor Management2. Storage(Memory) Management3. Information Management.

Operating System Function:

Major OS Functions are listed below:1. Processor Management2. Storage(Memory) Management3. Information Management.




Processor Management

• Means managing the process or processor i.e. CPU.

• This function is also termed as The benefits of multiprogramming are as follows:

• Increased CPU utilization• Higher total job throughput.• Where Throughput is the amount of work

accomplished in a given time interval.

Throughput = the number of jobs completedTotal time taken to complete the jobs.

Processor Management

Means managing the process or processor i.e.

This function is also termed as CPU Scheduling.The benefits of multiprogramming are as follows:

Increased CPU utilizationHigher total job throughput.Where Throughput is the amount of work accomplished in a given time interval.

Throughput = the number of jobs completedTotal time taken to complete the jobs.




Job Scheduling:

Before we study scheduling, we need to study certain concepts,

Another important factor that influences throughput is priority assigned to different jobs i.e. job scheduling.Program : is a set of instructions submitted to the computer.Process: is a program in execution.Job and Process are the terms which are almost used interchangeably.

Job Scheduling:

Before we study scheduling, we need to study certain

Another important factor that influences throughput is priority assigned to different jobs i.e. job scheduling.

: is a set of instructions submitted to the

: is a program in execution.are the terms which are almost used




Process States

• As we know that the process is a program in execution and therefore it changes states.

• A process can have these states: waiting or halted.

New Active

Waiting

Process States

As we know that the process is a program in execution and therefore it changes states.A process can have these states: new, active,

Active Halted

Waiting




• Now each process is represented in the OS by a block called Process Control Block(PCB).

• A PCB contains following information:i) Process Stateii) Program Counter : indicates the address of the

next instruction to be executed.iii) CPU Register: Stores system related informationiv) Memory limitsv) List of Open Files.

Now each process is represented in the OS by a block called Process Control Block(PCB).A PCB contains following information:

ii) Program Counter : indicates the address of the next instruction to be executed.

iii) CPU Register: Stores system related information




Many factors determine which scheduling technique to be used in order to have best possible results. The criteria is as follows :

• CPU Utilization: There should be maximum possible CPU utilization.

• Turnaround Time: There should be minimum possible turnaround time.

• Waiting Time: Waiting time should be minimum.• Response Time: System should give fastest response time.• Throughput: Throughput should be maximum possible.• Considering all these factors, scheduling technique is

chosen. There are two types of scheduling:A) Non-Preemptive schedulingB) Preemptive Scheduling

Many factors determine which scheduling technique to be used in order to have best possible results. The criteria is as follows :

: There should be maximum possible CPU

There should be minimum possible

Waiting time should be minimum.System should give fastest response time.

Throughput should be maximum possible.Considering all these factors, scheduling technique is chosen. There are two types of scheduling:

Preemptive scheduling




Non-Preemptive Scheduling• A scheduled job always gets completed before another scheduling

decision is made.• Finishing order of the jobs is same as their scheduling order.The scheduling techniques which use non

i) First Come First Serve Scheduling (FCFS)technique.

- uses FIFO( First in First Out) Concept i.e. the process which requests the CPU first, is allocated the CPU first.

- all processes, that want CPU time are entered in a queue called ready queue.

- the jobs in the ready queue are executed one by one.- Turnaround time for the first job is best and the last job is worst.

Note : Turnaround Time = delay between job submission and job completion.

Preemptive SchedulingA scheduled job always gets completed before another scheduling

Finishing order of the jobs is same as their scheduling order.The scheduling techniques which use non-preemptive scheduling are:

First Come First Serve Scheduling (FCFS)- simplest scheduling

uses FIFO( First in First Out) Concept i.e. the process which requests the CPU first, is allocated the CPU first.all processes, that want CPU time are entered in a queue called ready

the jobs in the ready queue are executed one by one.Turnaround time for the first job is best and the last job is worst.

Note : Turnaround Time = delay between job submission and job




ii) Shortest Job Next Scheduling – in this kind of scheduling, whenever a new job is submitted, the job which has the shortest waiting time is selected and given the CPU Time.

- throughput time remains same as in FCFS but waiting time improves.- one disadvantage is process starvation.

iii) Deadline Scheduling- In this scheduling the job with the earliest deadline is selected.

- deadline = time within which a job must be over.- places process in priority queue.

K = C-DWhere K = deadline overrun

C = job completion timeD = deadline for a job

in this kind of scheduling, whenever a new job is submitted, the job which has the shortest waiting time is selected and given the CPU Time.throughput time remains same as in FCFS but waiting time improves.

one disadvantage is process starvation.In this scheduling the job with the earliest

deadline = time within which a job must be over.




Preemptive Scheduling

• In this a scheduling decision can be made even while the job is executing.

• Preemptive scheduling may force a job in execution to release the processor, so that execution of some other job can be undertaken.

• This improves the throughput considerably.• The techniques which are used in preemptive

scheduling are:i) Round Robin Scheduling

programs equal opportunity to make progress.- time slices are assigned to each process in equal portions and in circular order, handling all

Preemptive Scheduling

In this a scheduling decision can be made even while the job is executing.Preemptive scheduling may force a job in execution to release the processor, so that execution of some other job can be undertaken.This improves the throughput considerably.The techniques which are used in preemptive

Round Robin Scheduling – aims at giving all the programs equal opportunity to make progress.

time slices are assigned to each process in equal portions and in circular order, handling all Print to PDF without this message by purchasing novaPDF (http://www.novapdf.com/)



ii) Response Ratio Scheduling Response ratio is defined as

Response Ratio = Elapsed time

- The job with highest response ratio is preferred over others.

- Suppose a shorter job arrives, it will have high response ratio, therefore will be executed first.

- Longer job will have to wait to achieve a higher response ratio.

Execution time received

ii) Response Ratio Scheduling –Response ratio is defined as

Response Ratio = Elapsed time

The job with highest response ratio is

Suppose a shorter job arrives, it will have high response ratio, therefore will be executed first.Longer job will have to wait to achieve a

Execution time received




Storage Management

• Memory plays a central role in the working of a computer.

• Both CPU and I/O devices interact with the memory.

- A program must be assigned some memory area and loaded into memory in order to get executed.

CPU Memory

Storage Management

Memory plays a central role in the working of

Both CPU and I/O devices interact with the

A program must be assigned some memory area and loaded into memory in order to get

I/O System




How is memory managed?

• There can be many user programs loaded into the memory along with system programs and operation system.

• We will study various approaches to memory management as follows:

(i) Contiguous Storage Allocation(ii) Non Contiguous Storage Allocation(iii)Virtual Storage Using Paging(iv)Virtual Storage Using Segmentation

How is memory managed?

There can be many user programs loaded into the memory along with system programs and

We will study various approaches to memory management as follows:

Contiguous Storage AllocationNon Contiguous Storage AllocationVirtual Storage Using PagingVirtual Storage Using Segmentation




Contiguous Storage Allocation

• Classical approach used for memory management.

• Each problem or program which is to be executed is allocated a contiguous storage memory.

• Each job is considered as a single independent entity for allocation of contiguous storage area.

• At every step the operating system has to ensure that there is sufficient memory area available.

Contiguous Storage Allocation

Classical approach used for memory

Each problem or program which is to be executed is allocated a contiguous storage

Each job is considered as a single independent entity for allocation of contiguous storage

At every step the operating system has to ensure that there is sufficient memory area




Non contiguous Storage Allocation

• A program can be stored in non contiguous memory area.

• A program is divided into smaller components of equal size.

• One or more components can be stored in the non contiguous memory areas.

• Each component in that particular area is provided addresses say 0,1,2………n.

• Suppose even if we use all available free memory areas still program cannot be loaded into the main storage because the total free space is less than the size of the program.

Non contiguous Storage Allocation

A program can be stored in non contiguous

A program is divided into smaller components

One or more components can be stored in the non contiguous memory areas.Each component in that particular area is provided addresses say 0,1,2………n. Suppose even if we use all available free memory areas still program cannot be loaded into the main storage because the total free space is less than the size of the program.




Virtual Storage using Paging.

• In computer operating systems, paging is one of the memory-management schemes by which a computer can store and retrieve data from secondary storage for use in main memory. Each program is split up into fixed size program components called pages.

• Pages in a program and each word in a page, both are numbered 0….n, i.e. their logical addresses.

• This range of logical addresses is called address space or logical address space.

• The range of physical storage area or memory is

Virtual Storage using Paging.

In computer operating systems, paging is one of management schemes by which a

computer can store and retrieve data from secondary storage for use in main memory. Each program is split up into fixed size program components called pages.Pages in a program and each word in a page, both are numbered 0….n, i.e. their logical addresses.This range of logical addresses is called virtual

logical address space.The range of physical storage area or memory is Print to PDF without this message by purchasing novaPDF (http://www.novapdf.com/)



• For program execution, its pages are loaded into any available frames.

• A page map table(PMT) stores entry for every program page which contains the frame(storage block) number where the page presently resides.

• The page number is used to index this table and the corresponding frame number is picked in order to access the page contents.

• In order to execute a program some of its pages are loaded into the main memory

For program execution, its pages are loaded into any available frames.A page map table(PMT) stores entry for every program page which contains the frame(storage block) number where the page

The page number is used to index this table and the corresponding frame number is picked in order to access the page contents.In order to execute a program some of its pages are loaded into the main memory




• When a required page is not in the main storage area, an interrupt called the missing page interrupt is raised.

• This fault interrupt is popularly known as page fault.

• The OS now takes the required action to bring the page from secondary storage into an empty block in main memory, this is also known as page-in.

• After page-in the PMT entry is modified and new entrant page physical address is also stored in it and the execution resumes.

When a required page is not in the main storage area, an interrupt called the missing page interrupt is raised.This fault interrupt is popularly known as page

The OS now takes the required action to bring the page from secondary storage into an empty block in main memory, this is also

the PMT entry is modified and new entrant page physical address is also stored in it and the execution resumes.




Virtual Storage using Segmentation.

• Similar to paging just that the program is divided into segments

• A program segment is a logical unit of program.

• For accessing a particular word in the segment, its logical address consists ofi) segment numberii) word number.

The segment number is mapped to a ‘segment table’ to get the physical address of the

Virtual Storage using Segmentation.

Similar to paging just that the program is instead of pages.

A program segment is a logical unit of

For accessing a particular word in the segment, its logical address consists of

The segment number is mapped to a ‘segment table’ to get the physical address of the Print to PDF without this message by purchasing novaPDF (http://www.novapdf.com/)



• In the hardware unit, Address Transformation Unit is responsible for generation of actual address of the required word within the segment.

• Segments in the memory are processed and if the segment is not available in the memory, a segment missing fault interrupt is raised.

• When segments are replaced, a single segment can only be replaced by a segment of the same size, or by a smaller segment.

• To increase efficiency paging and

In the hardware unit, Address Transformation Unit is responsible for generation of actual address of the required word within the

Segments in the memory are processed and if the segment is not available in the memory, a segment missing fault interrupt is raised.When segments are replaced, a single segment can only be replaced by a segment of the same size, or by a smaller segment.To increase efficiency paging and




Paging Vs Segmentation

• Paging – Computer memory is divided into small partitions that are all the same size and referred to as, page frames. Then when a process is loaded it gets divided into pages which are the same size as those previous frames. The process pages are then loaded into the frames.

• Segmentation – Computer memory is allocated in various sizes (segments) depending on the need for address space by the process. These segments may be

Paging Vs Segmentation

Computer memory is divided into small partitions that are all the same size and referred to as, page frames. Then when a process is loaded it gets divided into pages which are the same size as those previous frames. The process pages are then loaded

Computer memory is allocated in various sizes (segments) depending on the need for address space by the process. These segments may be Print to PDF without this message by purchasing novaPDF (http://www.novapdf.com/)



So now we can distinguish the differences and look at a comparison between the two:

• Paging:Transparent to programmer (system allocates memory)No separate protectionNo separate compilingNo shared code

• Segmentation:Involves programmer (allocates memory to specific function inside code)

So now we can distinguish the differences and look at a comparison between the two:

Transparent to programmer (system allocates

No separate protectionNo separate compiling

Involves programmer (allocates memory to specific function inside code)




Information Management

To manage information OS has one component known as Information Management Component.

This Information Management Component is structured as follows:

i ) Physical IOCS(Input Output Control System)responsible for device management for ensuring device independence.

- provides a basic capability for the programs to perform their own IO, without getting involved with the complexities of device handling.

ii ) Logical IOCS – responsible for efficient

Information Management

To manage information OS has one component Information Management Component.

This Information Management Component is

(Input Output Control System)-responsible for device management for ensuring

provides a basic capability for the programs to perform their own IO, without getting involved with the complexities of device handling.

responsible for efficient Print to PDF without this message by purchasing novaPDF (http://www.novapdf.com/)



Part

Evolution of Computers.

Part - II

Evolution of Computers.




Evolution of Computers

“Necessity is the mother of all inventions”Computers evolved as we needed a device that can perform fast calculations.Ancient people used stones for counting or made scratches on a wall or tie knots in a rope to record information.But, all these were manual computing techniques.

Evolution of Computers

“Necessity is the mother of all inventions”Computers evolved as we needed a device that can perform fast calculations.Ancient people used stones for counting or made scratches on a wall or tie knots in a rope

But, all these were manual computing




Let us take a look at the development of the computer through various stages:

ABACUS:• Invented around 3000years even before the birth of

Jesus Christ.• Invented by the Mesopotamians.• It laid the foundation of the computer era.• The Mesopotamians discovered the earliest form of

bead-and-wire counting machine subsequently came to be known as

• Chinese improved upon the abacus so that they could count and calculate fast.

Let us take a look at the development of the computer through various stages:

ABACUS:Invented around 3000years even before the birth of

Invented by the Mesopotamians.It laid the foundation of the computer era.The Mesopotamians discovered the earliest form of

counting machine - which subsequently came to be known as abacus.Chinese improved upon the abacus so that they could count and calculate fast.




Abacus contd..

• It consists of beads divided into two parts which are movable on the rods of two parts.

• Addition and multiplication etc. of numbers is done by using the place value of the digits of the numbers and position of beads in the abacus.

Abacus contd..

It consists of beads divided into two parts which are movable on the rods of two parts.Addition and multiplication etc. of numbers is done by using the place value of the digits of the numbers and position of beads in the




Napier’s ‘Logs’ and ‘Bones’

• Developed by John Napier(1550• He developed an idea of Logarithm• Used ‘logs’ to convert multiplication problem

into addition problem.• Napier’s logs later became the basics for a

well known invention-known as ‘slide-rule’(invented in 1662).

Napier’s ‘Logs’ and ‘Bones’

Developed by John Napier(1550-1617)He developed an idea of Logarithm in 1614.Used ‘logs’ to convert multiplication problem into addition problem.Napier’s logs later became the basics for a

computing machine rule’(invented in 1662).




Napier’s logs and bones contd..

• He also devised a set of numbering rods known as Napier’s bones.

• Both multiplication and addition can be performed with these bones.

• Reduced the tedium of repetitive calculations.

Napier’s logs and bones contd..

He also devised a set of numbering rods known as Napier’s bones.Both multiplication and addition can be performed with these bones.Reduced the tedium of repetitive calculations.




Pascal’s Adding Machine

• Developed by Blaise Pascal, a French Mathematician in 1642.

• Made up of gears which was used for adding numbers quickly.

• This machine was named as Adding Machine(also known as Pascaline)

• It was capable of performing addition subtraction.

Pascal’s Adding Machine

Developed by Blaise Pascal, a French Mathematician in 1642.Made up of gears which was used for adding

This machine was named as Adding Machine(also known as Pascaline)It was capable of performing addition




Pascal’s Machine contd..

• Worked on a clock work mechanism.• Consisted of numbered toothed wheels having

unique position values.• Rotation of wheels controlled the addition and

subtraction operations.• Capable of carry-transfer automatically.

Pascal’s Machine contd..

Worked on a clock work mechanism.Consisted of numbered toothed wheels having unique position values.Rotation of wheels controlled the addition and subtraction operations.

transfer automatically.




Leibnitz’s Calculator

• Developed by Gotfried Leibnitz, a German Mathematician in 1671.

• He improved upon adding machine and developed a new machine that was capable of performing multiplication and division as well.

• It performed multiplication through repeated addition of numbers.

Leibnitz’s Calculator

Developed by Gotfried Leibnitz, a German Mathematician in 1671.He improved upon adding machine and developed a new machine that was capable of performing multiplication and division as well.It performed multiplication through repeated




Leibnitz’s Calculator contd..

• It worked on the principle of step cylinders instead of wheels used by Pascal.

• Each step cylinder consisted of nine teeth of varying lengths.

Leibnitz’s Calculator contd..

It worked on the principle of step cylinders instead of wheels used by Pascal.Each step cylinder consisted of nine teeth of




Jacquard’s Loom

• Developed by Joseph Jacquard in 1801.• He manufactured punched cards at the end of

American Revolution and used them to control looms.

• Entire control weaving process was automatic.• Entire operation was under a program’s

control.

Jacquard’s Loom

Developed by Joseph Jacquard in 1801.He manufactured punched cards at the end of American Revolution and used them to

Entire control weaving process was automatic.Entire operation was under a program’s




Jacquard's Loom contd..

With invention of punched cards the era of store and retrieve information started which greatly

influenced the later inventions and advancements.

Jacquard's Loom contd..

With invention of punched cards the era of store and retrieve information started which greatly

influenced the later inventions and advancements.




Babbage’s Difference Engine

• Developed by Charles Babbage, a professor of mathematics in 1822.

• This machine was expected to calculate logarithmic tables to higher degree of precision.

• It was used to calculate various mathematical functions

Babbage’s Difference Engine

Developed by Charles Babbage, a professor of

This machine was expected to calculate logarithmic tables to higher degree of

It was used to calculate various mathematical




Difference Engine contd..

• Was capable of polynomial evaluation by finite difference.

• Its operation was automatic multistep operation.

Difference Engine contd..

Was capable of polynomial evaluation by

Its operation was automatic multistep




Babbage’s Analytical Engine

• Charles Babbage started designing the Analytical Engine in 1833.

• Became the basis or the real ancestor of modern day computer.

• Methodically designed, therefore established the basic principles on which the today’s computers work.

• Was capable of performing all four arithmetic operations as well as comparison.

Babbage’s Analytical Engine

Charles Babbage started designing the Analytical Engine in 1833.Became the basis or the real ancestor of modern day computer.Methodically designed, therefore established the basic principles on which the today’s

Was capable of performing all four arithmetic operations as well as comparison.




Analytical Engine contd..

• Babbage included the concept of centralprocessor, storage area, memory and inputoutput devices in his design.

• First innovation – enabled the machine to compare quantities and then decide which instruction sequence to follow.

• Second innovation- permitted the results of a calculation to change numbers and instructions already stored in the machine i.e. modification of stored information.


Babbage included the concept of central-processor, storage area, memory and input-output devices in his design.

enabled the machine to compare quantities and then decide which instruction sequence to follow.

permitted the results of a calculation to change numbers and instructions already stored in the machine i.e. modification of stored information.





• But, due to limitations it was never built, remained as conceptual design.

• Owing to his great inventions Charles Babbage came to be known as ‘Father of Modern Computers’.


But, due to limitations it was never built, remained as conceptual design.Owing to his great inventions Charles Babbage came to be known as ‘Father of Modern




Hollerith’s Machine

• Developed by Herman Hollerith in 1887.• He fabricated the idea that was dreamt by

Charles Babbage.• He invented the first electromechanical

punched-card tabulator.• Used punched cards for input, output and

instructions.

Hollerith’s Machine

Developed by Herman Hollerith in 1887.He fabricated the idea that was dreamt by

He invented the first electromechanical card tabulator.

Used punched cards for input, output and




Hollerith’s Machine contd..

• It was used by American Center of Census to compile their 1880 census data.

• They were able to complete compilation in 3years which earlier used to take around 10years.

Hollerith’s Machine contd..

It was used by American Center of Census to compile their 1880 census data.They were able to complete compilation in 3years which earlier used to take around




Mark

• Developed by Prof. Howard Aiken in U.S.A in 1943.

• He developed an electromechanical computer named Mark-I.

• It could multiply two 10seconds- record at that time.

• It was the first machine which could perform according to pre-programmed instructions automatically without any manual interference.

Mark-I

Developed by Prof. Howard Aiken in U.S.A in

He developed an electromechanical computer

It could multiply two 10-digits number in 5 record at that time.

It was the first machine which could perform programmed instructions

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Part

Strengths and Weaknesses of a Computer

Part – III

Strengths and Weaknesses of a Computer




Strengths of a Computer

• Speed• High Storage Capacity• Accuracy• Reliability• Versatility

Strengths of a Computer




Weaknesses of a Computer

• Lack of Decision Making Power.• Zero IQ

Weaknesses of a Computer

Lack of Decision Making Power.




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