UTILITY SOFTWARE

Utility software helps the user to control, manage, and maintain a computer's operating system, hardware and application software. These programs are designed to perform specific functions like finding files, backing up data, playing multimedia files, viewing images and so on. Unlike system software, utility software can be set up, controlled or initiated by the user. Many utility software programs are built into a computer's operating system.

There are also stand-alone utility programs such as backup utilities and antivirus programs. Typically, these programs come with additional features that help improve the already built-in software. They have to be installed to the computer by the user, and they do not depend on other software packages to function. These programs remove spyware and adware, compress files, burn CDs and DVDs, play media files, convert files from one format to another and do other unglamorous tasks

EXAMPLE UTILITY SOFTWARE

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Compiler, Interpreter, Linker, Loader

Assembler: A computer will not understand any program written in a language, other than its machine language. The programs written in other languages must be translated into the machine language. Such translation is performed with the help of software. A program which translates an assembly language program into a machine language program is called an assembler. If an assembler which runs on a computer and produces the machine codes for the same computer then it is called self assembler or resident assembler. If an assembler that runs on a computer and produces the machine codes for other computer then it is called Cross Assembler.

Assemblers are further divided into two types: One Pass Assembler and Two Pass Assembler. One pass assembler is the assembler which assigns the memory addresses to the variables and translates the source code into machine code in the first pass simultaneously. A Two Pass Assembler is the assembler which reads the source code twice. In the first pass, it reads all the variables and assigns them memory addresses. In the second pass, it reads the source code and translates the code into object code.

Compiler: It is a program which translates a high level language program into a machine language program. A compiler is more intelligent than an assembler. It checks all kinds of limits, ranges, errors etc. But its program run time is more and occupies a larger part of the memory. It has slow speed. Because a compiler goes through the entire program and then translates the entire program into machine codes. If a compiler runs on a computer and produces the machine codes for the same computer then it is known as a self compiler or resident compiler. On the other hand, if a compiler runs on a computer and produces the machine codes for other computer then it is known as a cross compiler.

Interpreter: An interpreter is a program which translates statements of a program into machine code. It translates only one statement of the program at a time. It reads only one statement of program, translates it and executes it. Then it reads the next statement of the program again translates it and executes it. In this way it proceeds further till all the statements are translated and executed. On the other hand, a compiler goes through the entire program and then translates the entire program into machine codes. A compiler is 5 to 25 times faster than an interpreter.

By the compiler, the machine codes are saved permanently for future reference. On the other hand, the machine codes produced by interpreter are not saved. An interpreter is a small program as compared to compiler. It occupies less memory space, so it can be used in a smaller system which has limited memory space.

Linker: In high level languages, some built in header files or libraries are stored. These libraries are predefined and these contain basic functions which are essential for executing the program. These functions are linked to the libraries by a program called Linker. If linker does not find a library of a function then it informs to compiler and then compiler generates an error. The compiler automatically invokes the linker as the last step in compiling a program.

Not built in libraries, it also links the user defined functions to the user defined libraries. Usually a longer program is divided into smaller subprograms called modules. And these modules must be combined to execute the program. The process of combining the modules is done by the linker.

Loader: Loader is a program that loads machine codes of a program into the system memory. In Computing, a loader is the part of an Operating System that is responsible for loading programs. It is one of the essential stages in the process of starting a program. Because it places programs into memory and prepares them for execution. Loading a program involves reading the contents of executable file into memory.  Once loading is complete, the operating system starts the program by passing control to the loaded program code. All operating systems that support program loading have loaders. In many operating systems the loader is permanently resident in memory. 

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INTRODUCTION OF COMPUTER

                         Computer

Computer is an automatic, electronic machine that

Accept data & instructions from a user (INPUT)

Store the data & instructions (STORAGE)

Manipulate the data according to the instructions (PROCESSING)

Store &/or output the results to the user (OUTPUT)

                         DATA

Data in a computer terminology mean raw facts and figures.

For ex-Mohan, 1977 etc.

                         INFORMATION

INFORMATION.  It means what we get after processing

   Data (meaningful data); Data are aggregated and summarized in various meaningful ways to form information for E.g.  Mohan’s roll no is 1977.

                        TYPES OF COMPUTERS

Computers can be classified into three categories:-

1.         Digital computers

2.         Analog computers

3.         Hybrid computers

                         DIGITAL COMPUTERS

The computers working upon binary digits are digital computers.

They are accurate and fast.

They have become omnipresent recently.

                          CLASSIFICATION OF DIGITAL COMPUTERS

These can be classified in two ways.

Purpose-wise

Size and performance wise

                        PURPOSE-WISE

On this basis there are two divisions:--

1. Special-purpose computers
2. General purpose computers

                         SPECIAL PURPOSE COMPUTERS

Those designed to perform a specific task.

The instructions are permanently scratched in the system itself.

Though they are accurate they aren't versatile.

                           GENERAL PURPOSE COMPUTERS

These are versatile computers which we generally use. These don’t have permanent programs (i.e. in memory) but many applications are available on many mediums like HD. These are called at the time of execution.

                            SIZE AND PERFORMANCE WISE

Embedded computers

Micro computers

Mini computers

Mainframe computers

Super computers

           Basic Parts of Computer

•  Hardware

          –     Mechanical devices in the computer

          –     Anything that can be touched

•      Software

       –     Tell the computer what to do

       –     Also called a program

       –     Thousands of programs exist

               Hardware

The term hardware refers to all of the physical devices, or components, that a computer is made

Of A computer is not one single device, but a system of devices that all work together. Like the

Different instruments in a symphony orchestra, each device in a computer plays its own part.

A typical computer system consists of the following major components:

• The central processing unit (CPU)

• Main memory

• Secondary storage devices

• Input devices

• Output devices

Input Devices

Input basically means getting data into the computer to be processed.

The most common input devices are Keyboard and Mouse,

Output Devices

Output basically means getting data out of the computer.

Examples are

Monitor

Printer

Speakers

Storage Devices

Storage devices are the one used to keep data that has been processed so that data can be retrieved at a later time to be used again.

Examples are:

Hard Disk

Floppy Disk

CD’s, DVD’s

Central Processing Unit (CPU)

The main chip in the computer.

It is the heart of the computer and communicates with the output, input and storage devices to perform tasks that are important to the functioning of the computer.

Its main function is

• to process instructions
• manage the flow of information through the computer system.
• perform calculations.

CPU composed of two main components:

Control Unit

Arithmetic and Logic Unit (ALU)

SOFTWARE

Software represents the set of programs that governs the operation of a computer system and make the hardware run. Software can be classified broadly into three categories:--

Operating System

Language processors

    (Operating System &Language processors are collectively called as system software.)

Application software 

LANGUAGE PROCESSORS

The system programs that perform the job of converting codes in computer understandable language are known as language processors.

The language processors are given below:-

Assembler .The language processor converts the program written in assembly language to machine language.

Interpreter this language processor converts a HLL program into machine language by converting and executing it line by line.  

Compiler it also converts a HLL program into machine language but a manner which is way different from an n assembler. It converts the entire program in one go, and reports the errors of the program along with line numbers.

A combination of compiler and assembler is best up to the requirement.        

 

APPLICATION SOFTWARE

Application software is the set of programs necessary to carry out operations for a specified application.

Application software can further be subdivided into two categories:

1. Customized application software. The type of application which is tailor made software according to a user’s requirement.

2. General application software. The type of software developed keeping in mind the general requirements for carrying out a specific task. Many users can use it simultaneously as it fulfills the general requirements.         

STRENGTHS AND WEAKNESSES OF A COMPUTER

STRENGTHS OF A COMPUTER

What has made the inevitable shift from manual style of working to computerized working possible?

There must be some advantages of computer over the previous. The strength of computers :-

Speed. Computers, much faster than human beings, can execute millions of instructions in one second and thus can perform a task in minute/s which if performed manually would eat days together.

High storage capacity. Computers can store a large amount of information in a very small space.

Accuracy. Computers can perform all the calculations and comparisons accurately provided the hardware doesn’t malfunction.

Reliability. Computers are immune to tiredness and boredom or fatigue. Thus they are more reliable than human beings.

Versatility. Computers can perform repetitive jobs efficiently. Along with it they can handle various tasks. They can work in areas where human mind can err. They can work with various types of data for ex—graphic, audio, visual, characters etc

WEAKNESSES OF A COMPUTER

But the advantages counted limitations remain because limitations must follow advantages.

Here limitations are:--

LACK OF DECISION MAKING POWER. Computers cannot decide on their own. They lack the power which is a great asset to us and everybody who is a human.

IQ ZERO. Computers are dumb machines with zero IQ. They need to be told

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BASIC LINUX

Ubuntu is one of the most customizable operating systems available. In order to begin to understand the various complexities of the system, you need to become familiar with the most basic commands at your disposal.

In this tutorial, we will introduce you to some of the everyday commands used on the operating system. These commands will help you as you interact with the Linux interface and try understand how to use its flexible operating system.

How to stat terminal

  Go to application (search ) menu and then type terminal

Or: You can click: Ctr + Alt + T

List of Beginner Ubuntu Commands

mv: Short for move, this command can be used to move your files from one folder to another.

rm: Short for remove, this command is used to remove any files or folders.

cd: Short for change, you can use this command to change your current directory.

cp: Short for copy, this command can be used to copy files or folders in a directory.

chown: This command is used to change ownership of a file.

chmod: This command is used to change permissions on a file.

ls: Short for list, this command can be used to view all of the files and folders in your current working directory.

pwd: Short for print working directory, this command can be used to display the directory in which you are currently working.

sudo: Also referred to as superuser do, a sudo command allows you to run other commands with administrative privileges. This command is especially useful for modifying files in a directory that a user wouldn't necessarily have access to.

cd: Short for change directory, this command can be used to change the directory in which you are currently working. There are a variety of cd commands that can be used to take you to specific files or folders.

cd / : An alternate to a basic cd command, the cd / command can be used to take you to the root directory.

cd .. : This command can be used to take you up one directory level.

cd - : This command can be used to navigate to a previous directory.

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DISK OPERATING SYSTEM

DOS (Disk Operating System) is an operating system that runs from a hard disk drive The term can also refer to a particular family of disk operating systems, most commonly                     

MS-DOS  (Microsoft Disk Operating System)

HOW TO START DOS?

Click start menu then writer cmd in search box then enter  then window pop up appear like this

Change Drives

To change to another disk drive, key in the drive letter ( ‘A’, ‘C’, ‘D’, etc) followed by a colon (‘:’) then press the <Enter> key.

The DIR Command 
We have a directory full of disk files
How do we look at what is on the disk or what files are in a directory?
What is a directory anyway? Use the DIR command

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COMPUTER HISTORY

EVOLUTION OF COMPUTERS

Ancient people used stones for counting or made scratches on wall or tied knots in a rope to record information. But all these were manual computing techniques. Attempts had been going on for developing faster computing devices and the first achievement was abacus, the pioneer computing device used by man.

ABACUS

Around 3000 B.C, the Mesopotamians quite unknowingly laid the foundation of  computer era.

They discovered an earliest form of a bead-and-wire counting machine, which subsequently came to be known as abacus. The Chinese improved upon the abacus so that they could calculate and count faster

NAPIER’S ‘LOGS’ AND ‘BONES

John napier (1550-1617) developed the idea of logarithm. He used logs to transform multiplication problem to addition problem. Napier’s logs and bones later became basis for a well known invention known –the computing machine known as “slide rule” (invented in 1662). Napier also advised a set of numbering rods known as Napier's bones. He could perform both multiplication and division with these ‘bones’.

PASCAL’S ADDING MACHINE

The idea of logarithm, developed in 1614, notably reduced the tedium of repetitive calculations.

Blasé Pascal, a French mathematician, invented a machine in 1642 made up of gears which was used for adding numbers quickly. This machine was known as adding machine (also known as Pascaline) and was capable of addition and subtraction.

PASCALINE

It worked on clock work mechanism principle. The adding machine consisted of numbered toothed wheels having unique position values. The rotation of wheels controlled the addition and subtraction operations. The machine was capable of carry-transfer automatically.

LEIBNITZ’S CALCULATOR

Gottfried Leibnitz, a german mathematician, improved an adding machine and constructed a new machine in 1617 that was capable to perform multiplication and division as well. This machine performed multiplication through repeated addition of numbers. Leibnitz’s machine used stepped cylinder each with nine teeth of varying lengths instead of wheels as was used by Pascal.

JACQUARD’S LOOM

Joseph jacquard manufactured punched cards at the end of American revolution and used them to control looms in 1801. Thus the entire control of weaving process was automatic. The entire operation was under control of a program . with the historic invention of punched cards, the era of  storing and retrieving information started that greatly influenced the later inventions and advancements.

BABBAGE’S DIFFERENCE ENGINE

Charles Babbage, a professor of mathematics, developed a machine called DIFFERENCE ENGINE in the year 1822.this machine was expected to calculate logarithmic table to a high degree of precision. The difference engine was to calculate various mathematical functions. The machine was capable of polynomial valuation by finite difference and it’s operation was automatic Multi-stop operation.

BABBAGE’S ANALYTICAL ENGINE

In 1833, Charles Babbage started designing an analytical engine which was to become real ancestor of modern day computer. With the methodical design of his analytical engine, Babbage meticulously established the basic principles on which today’s computers work.

The first innovation enabled the machine to compare quantities and then decide which of the instruction sequences to follow. The second permitted the results of a calculation to change numbers and instructions already stored in the machine.

His great inventions of difference engine and analytical engine earned Charles Babbage the title “FATHER OF MODERN COMPUTERS”.

MARK-1

Prof. Howard  Aiken (1900-1973) in USA constructed in 1943 an electromechanical computer called mark-1 which could multiply two ten digit numbers in 5 seconds- a record back then.MARK-1 was the first computer which could perform automatically without any manual intervention according to preprogrammed codes.    

   COMPUTER GENERATION
Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to distinguish between varying hardware technologies. But nowadays, generation includes both hardware and software, which together make up an entire computer system. There are totally five computer generations known till date. Each generation has been discussed in detail along with their time period and characteristics. Here approximate dates against each generations have been mentioned which are normally accepted. Following are the main five generations of computers1. First GenerationThe period of first generation: 1946-1959. Vacuum tube based.

2. Second GenerationThe period of second generation: 1959-1965. Transistor based.

3. Third GenerationThe period of third generation: 1965-1971. Integrated Circuit based.

4. Fourth GenerationThe period of fourth generation: 1971-1980. VLSI microprocessor based.

5. Fifth GenerationThe period of fifth generation: 1980-onward. ULSI microprocessor based







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OPERATING SYSTEM

OPERATING SYSTEM

An OPERATING SYSTEM is a program which acts as a n interface between a user and the hardware (i.e. all the computer resources).

OS controls are a major component of a system and controls all other components. 

FUNCTIONS OF OPERATING SYSTEM

Provide a user interface

 Performing housekeeping procedures requested by the user, often concerning storage devices, such as

Reorganizing a hard drive, deleting files, copying files, and changing the system date • providing a way

For the user to manage the desktop, hardware, applications, and data

 Manage files

 Managing files on hard drives, DVD drives, CD drives, USB flash drives, and other drives • Creating,

Storing, retrieving, deleting, and moving files

 Manage hardware

 Managing the BIOS (programs permanently stored on hardware devices) • Managing memory, which is

A temporary place to store data and instructions as they are being processed • Diagnosing problems

With software and hardware

 Manage applications

 Installing and uninstalling applications • Running applications and managing the interface to the

Hardware on behalf of an application

OS (INTERFACE MANAGER)

TYPES OF OPERATING SYSTEM

There are many types of OS:-

Batch operating system

The users of a batch operating system do not interact with the computer directly. Each user prepares his job on an off-line device like punch cards and submits it to the computer operator. To speed up processing, jobs with similar needs are batched together and run as a group. The programmers leave their programs with the operator and the operator then sorts the programs with similar requirements into batches.

The problems with Batch Systems are as follows −

Lack of interaction between the user and the job.

CPU is often idle, because the speed of the mechanical I/O devices is slower than the CPU.

Difficult to provide the desired priority.

Time-sharing operating systems

Time-sharing is a technique which enables many people, located at various terminals, to use a particular computer system at the same time. Time-sharing or multitasking is a logical extension of multi programming. Processor's time which is shared among multiple users simultaneously is termed as time-sharing.

The main difference between Multi programmed Batch Systems and Time-Sharing Systems is that in case of Multi programmed batch systems, the objective is to maximize processor use, whereas in Time-Sharing Systems, the objective is to minimize response time.

Multiple jobs are executed by the CPU by switching between them, but the switches occur so frequently. Thus, the user can receive an immediate response. For example, in a transaction processing, the processor executes each user program in a short burst or quantum of computation. That is, if n users are present, then each user can get a time quantum. When the user submits the command, the response time is in few seconds at most.

The operating system uses CPU scheduling and multi programming to provide each user with a small portion of a time. Computer systems that were designed primarily as batch systems have been modified to time-sharing systems.

Advantages of Time sharing operating systems are as follows −

Provides the advantage of quick response.

Avoids duplication of software.

Reduces CPU idle time.

Disadvantages of Time-sharing operating systems are as follows −

Problem of reliability.

Question of security and integrity of user programs and data.

Problem of data communication.

Distributed operating System

Distributed systems use multiple central processors to serve multiple real-time applications and multiple users. Data processing jobs are distributed among the processors accordingly.

The processors communicate with one another through various communication lines (such as high-speed buses or telephone lines). These are referred as loosely coupled systems or distributed systems. Processors in a distributed system may vary in size and function. These processors are referred as sites, nodes, computers, and so on.

The advantages of distributed systems are as follows −

With resource sharing facility, a user at one site may be able to use the resources available at another.

Speedup the exchange of data with one another via electronic mail.

If one site fails in a distributed system, the remaining sites can potentially continue operating.

Better service to the customers.

Reduction of the load on the host computer.

Reduction of delays in data processing.

Network operating System

A Network Operating System runs on a server and provides the server the capability to manage data, users, groups, security, applications, and other networking functions. The primary purpose of the network operating system is to allow shared file and printer access among multiple computers in a network, typically a local area network (LAN), a private network or to other networks.

Examples of network operating systems include Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.

The advantages of network operating systems are as follows −

Centralized servers are highly stable.

Security is server managed.

Upgrades to new technologies and hardware can be easily integrated into the system.

Remote access to servers is possible from different locations and types of systems.

The disadvantages of network operating systems are as follows −

High cost of buying and running a server.

Dependency on a central location for most operations.

Regular maintenance and updates are required.

Real Time operating System

A real-time system is defined as a data processing system in which the time interval required to process and respond to inputs is so small that it controls the environment. The time taken by the system to respond to an input and display of required updated information is termed as the response time. So in this method, the response time is very less as compared to online processing.

Real-time systems are used when there are rigid time requirements on the operation of a processor or the flow of data and real-time systems can be used as a control device in a dedicated application. A real-time operating system must have well-defined, fixed time constraints, otherwise the system will fail. For example, Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc.

There are two types of real-time operating systems.

Hard real-time systems

Hard real-time systems guarantee that critical tasks complete on time. In hard real-time systems, secondary storage is limited or missing and the data is stored in ROM. In these systems, virtual memory is almost never found.

Soft real-time systems

Soft real-time systems are less restrictive. A critical real-time task gets priority over other tasks and retains the priority until it completes. Soft real-time systems have limited utility than hard real-time systems. For example, multimedia, virtual reality, Advanced Scientific Projects like undersea exploration and planetary rovers, etc.

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