Secondary Memory

All secondary storage devices which are capable of storing high volume data is referred to secondary memory. It's slower than primary memory. However, it can save a substantial amount of data, in the range of gigabytes to terabytes. This memory is also called backup storage or mass storage media.

Types of Secondary memory

Mass storage devices:

The magnetic disk provides cheap storage and is used for both small and large computer systems.

Two types of magnetic disks are:

• Floppy disks
• Hard disks

Flash/SSD

Solid State Drive provides a persistent flash memory. It's very fast compared to Hard Drives. Frequently found in Mobile phones, its rapidly being adopted in PC/Laptop/Mac.

Optical drives:

This secondary storage device is from which data is read and written with the help of lasers. Optical disks can hold data up to 185TB.

Examples

• CD
• DVD
• Blue Ray

USB drives:

It is one of the most popular types of secondary storage device available in the market. USB drives are removable, rewritable and are physically very small. The capacity of USB drives is also increasing significantly as today 1TB pen drive is also available in the market.

Magnetic tape:

It is a serial access storage device which allows us to store a very high volume of data. Usually used for backups.

Characteristic Secondary Memory

• These are magnetic and optical memories
• Secondary memory is known as a backup memory
• It is a non-volatile type of memory
• Data is stored permanently even when the power of the computer is switched off
• It helps store data in a computer
• The machine can run without secondary memory
• Slower than primary memory

Primary Memory

Primary memory is computer memory that is accessed directly by the CPU.RAM, or random access memory, consists of one or more memory modules that temporarily store data while a computer is running.

Primary memory is also known as Main memory or Internal memory.

RAM is volatile memory, meaning it is erased when the power is turned off.

Characteristic of Primary Memory

• The computer can't run without primary memory
• It is known as the main memory.
• You can lose data in case power is switched off
• It is also known as volatile memory
• It is a working memory of the computer.
• Primary memory is faster compares to secondary memory.

Two Types of Primary Memory are:

• RAM
• ROM

RAM

The full form of RAM is Random Access Memory. The information stored in this type of memory is lost when the power supply to the PC or laptop is switched off. The information stored in RAM can be checked with the help of BIOS. It is generally known as the main memory or temporary memory or cache memory or volatile memory of the computer system.

Two main types of RAM are:

• Static RAM
• Dynamic RAM

Static RAM

Static RAM is the full form of SRAM. In this type of RAM, data is stored using the state of a six transistor memory cell. Static RAM is mostly used as a cache memory for the processor (CPU).

Dynamic RAM

DRAM stands for Dynamic Random Access Memory. It is a type of RAM which allows you to stores each bit of data in a separate capacitor within a specific integrated circuit. Dynamic RAM is a standard computer memory of the many modern desktop computers.

This type of RAM is a volatile memory that needs to be refreshed with voltage regularly. Else it loses the information stored on it.

Uses of RAM

Here, are important uses of RAM:

• RAM is utilized in the computer as a scratchpad, buffer, and main memory.
• It offers a fast operating speed.
• It is also popular for its compatibility
• It offers low power dissipation

ROM

ROM (read only memory) is a flash memory chip that contains a small amount of non-volatile memory. Non-volatile means that its contents cannot be changed and it retains its memory after the computer is turned off.

Types of ROM

PROM: Programmable ROM, or PROM, is essentially a blank version of ROM that you can purchase and program once with the help of a special tool called a programmer. A blank PROM chip allows current to run through all possible pathways; the programmer chooses a pathway for the current by sending a high voltage through the unwanted fuses to “burn” them out. Static electricity can create the same effect by accident, so PROMs are more vulnerable to damage than conventional ROMs.

EPROM: Erasable Programmable ROM chips allow you to write and rewrite them many times. These chips feature a quartz window through which a specialized EPROM programmer emits a specific frequency of ultraviolet light. This light burns out all the tiny charges in the EPROM to reopen its circuits. This exposure effectively renders the chip blank again, after which you can reprogram it according to the same process as a PROM. EPROM chips will eventually wear out, but they frequently have lifetimes of over 1000 erasures.

EEPROM: To modify an Electrically Erasable Programmable ROM chip, apply localized electrical fields to erase and rewrite the data. EEPROMs have several advantages over other types of ROM. Unlike the earlier forms, you can rewrite EEPROM without dedicated equipment, without removing it from the hardware, and in specifically designated increments. You don’t have to erase and rewrite everything to make a single edit.

Cache Memory

Cache memory is an extremely fast memory type that acts as a buffer between RAM and the CPU. It holds frequently requested data and instructions so that they are immediately available to the CPU when needed. Cache memory is used to reduce the average time to access data from the Main memory.

Register

A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only.

 

 

Software Concepts

A Computer is an electronic device that can perform various operations of computation at a greater speed than what an ordinary machine or human mind can do. It is driven by many entities including the physical and tangible components that we can touch or feel, called the Hardware and programs and commands that drive the hardware, called the Software.
The Software refers to the set of instructions fed in form of programs to govern the computer system and process the hardware components. For example:

• The antivirus that we use to protect our computer system is a type of Software.
• The media players that we use to play multimedia files such as movies, music etc. are Software.
• The Microsoft Office we use to edit the documents is a Software.

Depending on its use and area of implementation, Softwares can be divided into 3 major types:

1. System Software
2. Application Software
3. Utility Software

System Software

These are the software that directly allows the user to interact with the hardware components of a computer system. As the humans and machines follow different languages, there has to be an interface that will allow the users to interact with the core system, this interface is provided by the software. The system software can be called the main or the alpha software of a computer system as it handles the major portion of running a hardware. This System Software can be further divided into four major types:

1. The Operating System – It is the main program that governs and maintains the inter-cooperation of the components of a computer system. For eg., Microsoft Windows, Linux, Mac OS etc.
2. The Language Processor – The hardware components present in the computer system does not understand human language. There are three types of languages involved in the world of human-machine interaction:
   
    
   
   
   • Machine-Level Language: The machines only understand the digital signals or the binary codes or the binary language which consist of strings of 0’s and 1’s. These are totally machine dependent language.
   • Assembly-Level Language: These are the Low-Level Language(LLL), that forms a correspondence between machine level instruction and general assembly level statements. Assembly language uses a mnemonics to represent each low-level machine instruction or operation-code also called the op-codes. For eg., ADD instruction is used to add two entities, the HALT instruction is used to stop a process etc. It is a machine dependent language and varies from processor to processor.
   • High-Level Language: These are the simple English statements, that humans use to program and code as it is easy to read and understand to the human world. For eg., Java, C, C++, Python etc.

   The machine level language is very complex to understand and code, therefore the users prefer the High-Level Language or the HLL for coding. These codes need to be converted into the machine language so that the computer can easily understand and work accordingly. This operation is performed by the Language Processor which is made up of further three components:

   • Assembler: This language processor is used to convert the assembly language into machine level language.
   • Compiler: This language processor is used to convert High-Level Language into machine level language in one go, thus execution time is fast. The error detection is difficult in a compiler. Programming Languages like C, C++ and Scala use compiler.
   • Interpreter: This language processor is also used to convert High-Level Language into machine level language line-by-line, thus execution time is slow. Error-detection is easier in an interpreter as it reports as soon as a bug is caught and restarts the process. This consumes unnecessary memory. Programming Languages like Python, Ruby and Java uses an interpreter.
3. The Device Drivers – The device drivers and the device programs or the system software that acts as an interface between the various Input-Output device and the users or the operating system. For eg., the Printers, Web cameras come with a driver disk that is needed to be installed into the system to make the device run in the system.
4. The BIOS – It stands for Basic Input Output System and is a small firmware, that controls the peripheral or the input-output devices attached to the system. This software is also responsible for starting the OS or initiating the booting process.

Application Software

These are the basic software used to run to accomplish a particular action and task. These are the dedicated software, dedicated to performing simple and single tasks. For eg., a single software cannot serve to both the reservation system and banking system. These are divided into two types:

1. The General Purpose Application Software: These are the types of application software that comes in-built and ready to use, manufactured by some company or someone. For eg.,
   • Microsoft Excel – Used to prepare excel sheets.
   • VLC Media Player – Used to play audio/video files.
   • Adobe Photoshop – Used for designing and animation and many more.
2. The Specific Purpose Application Software: These are the type of software that is customizable and mostly used in real-time or business environment. For eg.,
   • Ticket Reservation System
   • Healthcare Management System
   • Hotel Management System
   • Payroll Management System

Utility Software

These are the most basic type of software which provides high utility to the user and the system. These perform the basic but daily need tasks. For eg.,

• Antivirus Softwares: These provide protection to the computer system from unwanted malware and viruses. For eg., QuickHeal, McAfee etc.
• Disk Defragmenter Tools: These help the users to analyse the bad sectors of the disk and rearrange the files in a proper order.
• Text-editors: These help the users to take regular notes and create basic text files. For eg., Notepad, Gedit etc.

Device Drivers

A device driver is a small piece of software that tells the operating system and other software how to communicate with a piece of hardware.

For example, printer drivers tell the operating system, and by extension whatever program you have the thing you want to print open in, exactly how to print information on the page

sound card drivers are necessary so your operating system knows exactly how to translate the 1s and 0s that comprise that MP3 File  into audio signals that the sound card can output to your headphones or speakers. 

The same general idea applies to video cards, keyboards, monitors, mice, disc drivers, etc.

Keep reading for more on why drivers are important, including some more examples, as well as information on how to keep your drivers updated and what to do if they're not working properly.

Working of Device Driver:
Device Drivers depend upon the Operating System’s instruction to access the device and performing any particular action. After the action they also shows their reactions by delivering output or status/message from hardware device to the Operating system.For Example a printer driver tells the printer in which format to print after getting instruction from OS, similarly A sound card driver is there due to which 1’s and 0’s data of MP3 file is converted to audio signals and you enjoy the music. Card reader, controller, modem, network card, sound card, printer, video card, USB devices, RAM, Speakers etc need Device Drivers to operate.

Office Tools

Office Tools include some Application Software that are used to create, update, manage documents, handle large data, create presentations etc. These tools if used effectively, can save a large amount of time and effort. Lots of repetitive tasks can be done very easily. In this article, we will discuss the following concepts:

• Word Processor
• Presentation Tool
• Spreadsheet Package
• Database Management System

1. Word Processor

Word Processor is a software that is used to manage text documents. User can create, update and formatting text files using word processor. It makes text document related work faster an easier. A word processor is an essential part of any office suite. A word processor usually runs on local machine as a desktop application like Microsoft word but nowadays cloud based Word Processors like Google docs are also used which makes it easier for teams to manage their documents on cloud.

Examples of some word processors are:

• MS-Word: Retail Cross-Platform word processor
• WordPad: Retail windows only word processor
• WordPerfect: Retail Cross-Platform word processor
• Google Docs: Freeware Cloud Based word processor
• LibreOffice Writer: Open Source word processor

Characteristics of word processor:

• Create, save and edit text documents.
• Includes text formatting like font size, alignment, font color, background color, etc.
• Checks spelling.
• Allows adding images, screenshots etc to document.
• Allows adding header and footer, set page margins and insert watermarks to your document.

2. Presentation Tool

A Presentation Tool is a software package used to display data and information in the form of a slide show. The information is broken into small pieces called slides. It has three major parts: editor that allows formatting and editing of text, method used for inserting and manipulating graphic images, screenshots etc, slide-show system to display the content in form of a slide show.

The Slides together are stacked up to make an idea presentable to audience to make up presentation.

Examples of some presentation tool are:

• MS-PowerPoint: Retail Cross-Platform presentation tool
• Lotus Freelance: proprietary software presentation tool
• Google Slides: Freeware Cloud Based presentation tool
• LibreOffice Impress: Open Source presentation tool

3. Spreadsheet Package

Spreadsheet Package is a software that allows users to store, process and modify data in a tabular form easily. It is an accounting tool to manage tabular data. In a Spreadsheet data is always stored in cells. A cell is intersection of rows and columns. functions and formulas can be used easily on cell and data can be processed using a spreadsheet tool.

Examples of some spreadsheet software are:

• MS-Excel: Retail Cross-Platform spreadsheet package
• Google Sheets: Freeware Cloud Based spreadsheet package
• LibreOffice Calc: Open Source spreadsheet package

Characteristics of spreadsheet package:

• User can handle simple calculations like addition, subtraction, average, counting, etc, very easily.
• User can Prepare charts and graphs on a group of data easily.
• Data formatting is efficient and effective.
• Cell formatting is easy.
• Logical Calculations can be done.

4. Database Management System

Database Management System is a software that manages data by storing them in tables to make up a database. A database is an organised collection of data accessed on a machine. A Database Management System interacts with data, users and application. User can store, read, update and can delete data based on his/her needs. A good DBMS provides a set of utilities to administrator to manage the data effectively.

Examples of some Database Management System are:

• MySQL
• PostgreSQL
• Oracle Database
• Microsoft Access.

Characteristics of Database Management System:

• Data storing, reading and updating.
• User accessibility.
• Recovering damaged data facilities.
• Authorization of administrator and data access.
• Defining constraints for dataset.

 

Classification of Computers

The computer systems can be classified on the following basis:

1. On the basis of size.
2. On the basis of functionality.
3. On the basis of data handling.

According to purpose, computers are either general purpose or specific purpose. General purpose computers are designed to perform a range of tasks. They have the ability to store numerous programs, but lack in speed and efficiency. Specific purpose computers are designed to handle a specific problem or to perform a specific task. A set of instructions is built into the machine.

Type of computers on the basis of Functionality & Data Handling:

Analog Computer 

 An analog computer (spelt analogue in British English) is a form of computer that uses continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved.

Digital Computer

 A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system.

Hybrid computer

Hybrid computers are computers that exhibit features of analog computers and digital computers. The digital component normally serves as the controller and provides logical and numerical operations, while the analog component often serves as a solver of differential equations and other mathematically complex equations.

Type of computers on the basis of Size:

Super Computer 

The fastest and most powerful type of computer Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy research, and petroleum exploration.

The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.

Mainframe Computer

A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe.

Mini Computer 

A mid sized computer. In size and power, minicomputers lie between workstations and mainframes. In the past decade, the distinction between large minicomputers and small mainframes has blurred, however, as has the distinction between small minicomputers and workstations. But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously.

Micro Computer or Personal Computer

• Desktop Computer: a personal or micro-mini computer sufficient to fit on a desk.

• Laptop Computer: a portable computer complete with an integrated screen and keyboard. It is generally smaller in size than a desktop computer and larger than a notebook computer.

• Palmtop Computer/Digital Diary /Notebook /PDAs: a hand-sized computer. Palmtops have no keyboard but the screen serves both as an input and output devices.

Workstations

A terminal or desktop computer in a network. In this context, workstation is just a generic term for a user’s machine (client machine) in contrast to a “server” or “mainframe.”

 

System software

A system software is a specific type of software that manages a computing device. The system software comprises the operating system, utility programmes, and device drivers. We will look at each of the three parts.

The system software is a collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software is generally prepared by the computer manufacturers. These software products comprise of programs written in low-level languages, which interact with the hardware at a very basic level. System software serves as the interface between the hardware and the end users.

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

Here is a list of some of the most prominent features of a system software −

• Close to the system
• Fast in speed
• Difficult to design
• Difficult to understand
• Less interactive
• Smaller in size
• Difficult to manipulate
• Generally written in low-level language

AN OPERATING SYSTEM

An operating system is software that manages hardware, software and other applications on a computing device. The operating system has different functions and tasks it carries out on a computing device. In order to make these functions easy to understand, they are grouped into the following categories:

• Disk management: Used to manage the drives installed in a computer e.g. partition drives, format drives, assign drive letters.
• Hardware management: Managing the interaction between hardware and software, as well as the different hardware devices.
• Graphics User Interface (GUI) management: Provides and manages the user interface that interacts with graphics and visual content on a computing device.
• I/O management: Managing the signals received from an input device and sending the correct signals to an output device.
• Process management: Managing the applications and the resources used by applications (Apps) on a computing device.
• File management: Managing the storage of files and folders on your storage device.
• Memory management: Managing the data stored on a computing device’s memory and once the processing is complete, this function tends to free up some space.
• Storage management: Processes used to improve the performance of data storage resources.

Types of operating systems

Up to now, you have been learning about and working with Microsoft Windows as an example of an operating system. This particular type of operating system is commonly known as a stand-alone operating system. In this unit, we will focus on the following three types of operating systems namely, stand-alone, network and embedded operating systems.

THE STAND-ALONE OPERATING SYSTEM

These operating systems function entirely independently from a network on a computer or mobile device. This ensures that the tasks of an operating system can be performed on the device.

THE NETWORK OPERATING SYSTEM

Network or server operating systems are operating systems designed to help computers work together on a network, rather than used in a stand-alone mode. For example, a large company may have a server running the Windows Server operating system in the organisation. A computer can connect to the same network to gain access to its information, resources, etc. Examples include: Windows Server, Red Hat Enterprise, Ubuntu Server, and UNIX.

THE EMBEDDED OPERATING SYSTEM

The embedded operating system is designed for a specific purpose e.g. Smart TVs that connect to the internet, a video camera (Wi-Fi) that can stream live footage and the GPS system that is installed in most mobile devices.

Compiler

A compiler is a special program that processes statements written in a particular programming language and turns them into machine language or "code" that a computer's processor uses. Typically, a programmer writes language statements in a language such as Pascal or C one line at a time using an editor.

Interpreter

In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program.

Assembler

An assembler is a program that converts assembly language into machine code. It takes the basic commands and operations from assembly code and converts them into binary code that can be recognized by a specific type of processor. Assemblers are similar to compilers in that they produce executable code.

Difference Between Compiler Interpreter and Assembler

Functionality

Compiler converts the whole high level language program to machine language at a time. Interpreter converts the high level language program to machine language line by line. In contrast, assembler converts assembly language program to machine language.

Language

Languages such as C, C++ use compilers to convert the code. Languages such as Ruby, Perl, Python, PHP uses an interpreter and assembly language uses an assembler.

Conclusion

Compiler, Interpreter and Assembler are language translators. The difference between compiler interpreter and assembler is that compiler converts whole high level language programs to machine language at a time while interpreter converts high level language programs to machine language line by line and assembler converts assembly language programs to machine language.

 

 

Utility software

Utility software is software designed to help to analyze, configure, optimize or maintain a computer. It is used to support the computer infrastructure - in contrast to application software, which is aimed at directly performing tasks that benefit ordinary users.

Utility software usually focuses on how the computer infrastructure (including the computer hardware, operating system, software and data storage) operates. Utility software, along with operating system software, is a type of system software, distinguishing it from application software.

• Anti Virus utilities scan for computer viruses.

• Archivers output a stream or a single file when provided with a directory or a set of files. Archive utilities, unlike archive suites, usually do not include compression or encryption capabilities. Some archive utilities may even have a separate un-archive utility for the reverse operation.

• Backup Software can make copies of all information stored on a disk and restore either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an event of accidental deletion).

• Clipboard Managers expand the clipboard functionality of an operating system .

• Cryptographic utilities encrypt and decrypt streams and files.

• Data Compression utilities output a shorter stream or a smaller file when provided with a stream or file.

• Data Synchronization utilities establish consistency among data from a source to a target data storage and vice versa. There are several branches of this type of utility:

  • File Synchronizatiion utilities maintain consistency between two sources. They may be used to create redundancy or backup copies but are also used to help users carry their digital music, photos and video in their mobile devices.

  • Revision Control utilities are intended to deal with situations where more than one user attempts to simultaneously modify the same file.

• Debuggers are used to test and “debug” other programs, mainly to solve programming errors. Also utilized for reverse engineering of software or systems.

• Disk Checkers can scan operating hard drive.

• Disk Cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the user to decide what to delete when their hard disk is full.

• Disk Compression utilities can transparently compress/uncompress the contents of a disk, increasing the capacity of the disk.

• Disk Defregmenters can detect computer files whose contents are scattered across several locations on the hard disk, and move the fragments to one location to increase efficiency.

• Disk Partitions can divide an individual drive into multiple logical drives, each with its own file system which can be mounted by the operating system and treated as an individual drive.

• Disk Space Analysers for the visualization of disk space usage by getting the size for each folder (including sub folders) & files in folder or drive. showing the distribution of the used space.

• Disk Storage utilities

• File Managers provide a convenient method of performing routine data management tasks, such as deleting, renaming, cataloging, uncataloging, moving, copying, merging, generating and modifying data sets.

• Hex Editiors directly modify the text or data of a file. These files could be data or an actual program.

• Memory Testers check for memory failures.

• Network Utilities analyze the computer’s network connectivity, configure network settings, check data transfer or log events.

• Package Managers are used to configure, install or keep up to date other software on a computer.

• Registry Cleaners clean and optimize the Windows Registry by removing old registry keys that are no longer in use.

• Screensavers were desired to prevent phosphor burn-in on CRT and plasma computer monitors by blanking the screen or filling it with moving images or patterns when the computer is not in use. Contemporary screensavers are used primarily for entertainment or security.

• System Monitors for monitoring resources and performance in a computer system.

• System Profilers provide detailed information about the software installed and hardware attached to the computer.

 

Functions of Operating System

An operating system has three main functions:

(1) manage the computer's resources, such as the central processing unit, memory, disk drives, and printers.

(2) establish a user interface.

(3) execute and provide services for applications software.

Operating System supports the basic functions of the computer and is a low-level software. The functions of operating systems are as described below:

i)  I/O Management:

OS manages I/O devices and makes the I/O process effective. OS accepts the input from the input device, stores it in the main memory, ask the CPU to process it and finally provides the result to the output devices for output.

ii) Command Interpreter:

Command interpreter is one of the part of operating system which reads the commands that user types in at a terminal, interprets them and translate them into a detailed set of instructions that the computer hardware can understand. It varies widely from one OS to other OS. Every OS must provide command interpreter for its operation.

iii) Memory Management:

Memory is the large array of words or bytes, each with its own address. When user requests CPU for read/write operation, OS determines the amount of memory required for the program instructions and data. Then, OS allocates required memory to load the program and data into RAM. When program terminates its memory area is free and the same memory area is allocated for other programs.

iv)  Process Management:

OS finds the status of processor and processes, chooses a job, chooses processer in the job, allocates the processor to the process and frees the processor when the process is executed.

v)  Time Sharing:

OS manages the time of CPU. The kernel OS checks frequency for other processes requesting CPU time. Time-sharing checks for CPU request from higher priority processes that are made every 10 milliseconds. When two or more processes at the same priority level are competing for the CPU time, CPU time is sliced into segments, defined by time slice and passed from process to process in a round robin fashion, preventing a single process from monopolizing the CPU until it blocks or terminates.

vi)  Security:

OS makes sure that only authorized users get access to the computer and its data and the users only do things they are authorized to do.

vii) Deadlock Prevention:

During processing, a situation can arise in which a resource shared by two or more processes cannot continue because the resource required by one process is held by the other. This situation is called deadlock. OS ensures that the above condition do not hold by carefully allocating resources.

viii)  Interrupt Handling:

Interrupt is a signal generated from a device or program when they need attention of the CPU. OS determines the type of interrupt and priority of the interrupt, stops the execution process of CPU, preserves the initial state of the CPU, perform the requested operation and brings the CPU at the same state when it was stopped.

ix) Virtual Storage:

If there are programs larger than main memory (RAM) of the computer, OS uses the reserved space in the secondary memory which is termed as virtual memory. It makes the execution of larger program (than RAM) possible but at the same times the operation becomes slower.

Features of Operating System (OS)

Here is a list important features of OS:

• Protected and supervisor mode
• Allows disk access and file systems Device drivers Networking Security
• Program Execution
• Memory management Virtual Memory Multitasking
• Handling I/O operations
• Manipulation of the file system
• Error Detection and handling
• Resource allocation
• Information and Resource Protection

 

 

Basics of computer

A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware, the operating system (main software), and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.

Computers are used as control system for a wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave oven and remote contols, factory devices such as industrial robots and computer-aided design, and also general purpose devices like persnol computer and mobile devices such as smartphones. The Internet is run on computers and it connects hundreds of millions of other computers and their users.

Characteristics of Computer

1. Speed: – As you know computer can work very fast. It takes only few seconds for calculations that we take hours to complete. You will be surprised to know that computer can perform millions (1,000,000) of instructions and even more per second.

Therefore, we determine the speed of computer in terms of microsecond (10-6 part of a second) or nanosecond (10 to the power -9 part of a second). From this you can imagine how fast your computer performs work.

2. Accuracy: – The degree of accuracy of computer is very high and every calculation is performed with the same accuracy. The accuracy level is 7.

 

determined on the basis of design of computer. The errors in computer are due to human and inaccurate data.

3. Diligence: – A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work.

4. Versatility: – It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electric bills.

5. Power of Remembering: – Computer has the power of storing any amount of information or data. Any information can be stored and recalled as long as you require it, for any numbers of years. It depends entirely upon you how much data you want to store in a computer and when to lose or retrieve these data.

 

6. No IQ: – Computer is a dumb machine and it cannot do any work without instruction from the user. It performs the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in what sequence. So a computer cannot take its own decision as you can. 

7. No Feeling: – It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.

8. Storage: – The Computer has an in-built memory where it can store a large amount of data. You can also store data in secondary storage devices such as floppies, which can be kept outside your computer and can be carried to other computers.

Basic Parts of Computer

Computer case

The computer case is the metal and plastic box that contains the main components of the computer, including the motherboard, central processing unit (CPU), and power supply. The front of the case usually has an On/Off button and one or more optical drives.

Computer cases come in different shapes and sizes. A desktop case lies flat on a desk, and the monitor usually sits on top of it. A tower case is tall and sits next to the monitor or on the floor. All-in-one computers come with the internal components built into the monitor, which eliminates the need for a separate case.

Monitor

The monitor works with a video card, located inside the computer case, to display images and text on the screen. Most monitors have control buttons that allow you to change your monitor's display settings, and some monitors also have built-in speakers.

Newer monitors usually have LCD (liquid crystal display) or LED (light-emitting diode) displays. These can be made very thin, and they are often called flat-panel displays. Older monitors use CRT (cathode ray tube) displays. CRT monitors are much larger and heavier, and they take up more desk space.

Keyboard

The keyboard is one of the main ways to communicate with a computer. There are many different types of keyboards, but most are very similar and allow you to accomplish the same basic tasks.

Mouse

The mouse is another important tool for communicating with computers. Commonly known as a pointing device, it lets you point to objects on the screen, click on them, and move them.

There are two main mouse types: optical and mechanical. The optical mouse uses an electronic eye to detect movement and is easier to clean. The mechanical mouse uses a rolling ball to detect movement and requires regular cleaning to work properly.

Mouse alternatives

There are other devices that can do the same thing as a mouse. Many people find them easier to use, and they also require less desk space than a traditional mouse. The most common mouse alternatives are below.

• Trackball: A trackball has a ball that can rotate freely. Instead of moving the device like a mouse, you can roll the ball with your thumb to move the pointer.
• Touchpad: A touchpad—also called a trackpad—is a touch-sensitive pad that lets you control the pointer by making a drawing motion with your finger. Touchpads are common on laptop computers.

Advantages Of Computer

Computer has made a very vital impact on society. It has changed the way of life. The use of computer technology has affected every field of life. People are using computers to perform different tasks quickly and easily. The use of computers makes different task easier. It also saves time and effort and reduces the overall cost to complete a particular task.

Many organizations are using computers for keeping the records of their customers. Banks are using computers for maintaining accounts and managing financial transactions. The banks are also providing the facility of online banking. The customers can check their account balance from using the internet. They can also make financial transaction online. The transactions are handled easily and quickly with computerized systems.

People are using computers for paying their bills, managing their home budgets or simply having some break and watching a movie, listening to songs or playing computer games. Online services like skype or social media websites are used for communication and information sharing purposes.

Computer can be used as a great educational tool. Students can have access to all sort of information on the internet. Some great websites like Wikipedia, Khan’s Academy, Code Academy, Byte-Notes provides free resources for students & professionals. 

Disadvantages Of Computer

The use of computer has also created some problems in society which are as follows.

Unemployment

Different tasks are performed automatically by using computers. It reduces the need of people and increases unemployment in society.

Wastage Of Time And Energy

Many people use computers without positive purpose. They play games and chat for a long period of time. It causes wastage of time and energy. Young generation is now spending more time on the social media websites like Facebook, Twitter etc or texting their friends all night through smartphones which is bad for both studies and their health. And it also has adverse effects on the social life.

Data Security

The data stored on a computer can be accessed by unauthorized persons through networks. It has created serious problems for the data security.

Computer Crimes

People use the computer for negative activities. They hack the credit card numbers of the people and misuse them or they can steal important data from big organizations.

Privacy Violation

The computers are used to store personal data of the people. The privacy of a person can be violated if the personal and confidential records are not protected properly.

Health Risks

The improper and prolonged use of computer can results in injuries or disorders of hands, wrists, elbows, eyes, necks and back. The users can avoid health risks by using the computer in proper position. They must also take regular breaks while using the computer for longer period of time. It is recommended to take a couple of minutes break after 30 minutes of computer usage.

Impact On Environment

The computer manufacturing processes and computer waste are polluting the environment. The wasted parts of computer can release dangerous toxic materials. Green computer is a method to reduce the electricity consumed and environmental waste generated when using a computer. It includes recycling and regulating manufacturing processes. The used computers must be donated or disposed off properly.

Web browser

This is application software for browsing the web, viewing documents, managing web applications, and performing other tasks on the Internet. The browser processes user requests, sends them to a server, retrieves data from the server, and outputs them as web pages.

Browsers are distributed free of charge. Microsoft Edge comes as part of the Windows operating system. Mozilla Firefox - separately or as part of Linux distributions. Safari is available on Mac OS. Google Chrome, Opera, and many other browsers - as a standalone application, they are downloaded separately.

Browser functions

• Downloading of various files
• Storage of data (passwords, bookmarks for important resources, history of visits)
• Information exchange (e-mail, chats, forums, social networks)
• Online commerce
• Online education

Microsoft Office

This is a Microsoft Office application package for the Windows, Android, macOS, and iOS operating systems. It includes software for working with texts, spreadsheets, databases, images, etc.

At present, Microsoft provides the purchase of Office in several options:

1. Microsoft 365. Provides the right to use the latest versions of Microsoft Office applications, as well as a number of certain services (Exchange Online, OneDrive, Skype for Business, etc.) on a monthly or annual subscription basis. Users can choose the type of plan that is suitable for them:

• for home and family
• for business
• for enterprise
• for education.

The type of plan will determine what applications you will have on your computer.

2. Office 2021. Purchased as a lump sum and gives you the right to use the Office version in perpetuity. Microsoft regularly updates the Office package by adding new applications or special tools. However, if you buy a particular version of Microsoft Office, for example, 2021, you can't upgrade to the next version of Office for free. You must purchase the new version at full price to upgrade.

Microsoft office also provides several plan options:

• Office for home and study 2021
• Office for home and business 2021
• Office Professional 2021.

Composition

• Microsoft Word is a text editor. It allows you to work with documents of various complexity.
• Microsoft Excel is a table editor. Supports all functions for creating tables of any complexity.
• Microsoft Outlook is a personal communicator. It includes a task scheduler, an e-mail manager, a calendar, and an address book.
• Microsoft PowerPoint - a program for preparing presentations.
• Windows Access - database management application.
• Microsoft Communicator (Microsoft Lync) - designed for organizing communication between people by means of voice, video conversations, and text messages.
• Microsoft Publisher - an application for producing a variety of publications. The application contains tools to help you create, customize and use marketing materials.
• Microsoft Visio - An application for working with business diagrams and technical charts.
• Microsoft Project is an application for project management.
• Microsoft Query - application for viewing and selecting information from databases.
• Microsoft OneNote is an application for recording and managing notes.
• Microsoft SharePoint Designer is an application for building applications on the Microsoft SharePoint platform.
• Microsoft Picture Manager is an application for working with images.
• Microsoft Document Image Writer is a virtual printer that prints Microsoft Document Imaging Format.
• Microsoft Diagnostics - diagnostics and recovery of damaged Microsoft Office applications.

Antivirus software

This is a program designed to recognize and fight computer viruses and malicious unwanted programs. In their work, these programs use different principles to find and cure infected files. For the normal operation of a PC, every user should keep an antivirus program updated as the developers of the virus programs are constantly improving them. Users can install antivirus software as part of the software or as a stand-alone application

If the antivirus program detects a virus in the file, it deletes the program code of the virus from it. If treatment is not possible, the infected file is completely deleted.

Device drivers

A driver is a program by which the operating system understands which devices are connected to your computer and how best to communicate with them. Drivers are developed by the manufacturers of these devices (graphics card, network card, sound card, printer, etc.).

For example, you may have purchased an input device, connected it to your computer, and see that the computer does not recognize it. When you install the necessary drivers for the device, the computer will understand what the device is, what it does, and how to use it. The drivers are installed from the disk that comes with the device, or from the official website of the device manufacturer. Or, for example, you bought a sound card, installed it, and noticed that you didn't experience a difference in the sound. In this case, too, you need to install the drivers for that sound card for the device to work properly.

Drivers need to be updated regularly for your computer devices to work properly.

Basic Programs

These are programs that are integrated into the operating system. That is, they do not need to be installed, they are already in your computer from the first time it is started.

Notepad

This is a simple text editor. You can use it to enter text, edit it, and save it on your computer. All text files created by Notepad have the ".txt" extension. If you change the font or character size - it changes in the whole file. You cannot change the style of individual characters.  Documents created in Notepad take up very little space on your computer.

If you put the code sequence ".LOG" in the topmost line of the program and save it, the current date and time are added to the file after opening it.

This program is mainly used as a day planner. More advanced users can write special commands into the notepad and use it to make a simple web page, or write simple programs.

Calculator

The calculator is designed to perform computational operations. Its interface imitates the appearance of a real calculator. Its buttons are pressed with the mouse, and numeric input is possible with the keyboard.

You can paste already prepared mathematical expressions into it and get the final result. For example, if you type "2*2=" in notepad, copy and paste it with "Ctrl+V" key combination into the calculator window, you will see the number 4 in the calculator window.

Operation modes

The calculator has several operation modes: normal, engineering, graphing, programmer, and date calculation. Also, the calculator is capable of converting currencies, volume, length, weight and mass, temperature, energy, area, speed, time, power, data, pressure and angle.

Paint

This is a multifunctional graphics editor. It is designed to create and edit drawings of different colors and designs.

You can use it to delete, paint over, or blur any unwanted parts of an image.

Tools

• Tool for freehand drawing of lines.
• A tool for drawing lines in the form of a pen.
• Creates a spot of pixels in the workspace.
• Deletes elements of the image, leaving the background color.
• Creation of standard shapes in the form of a rectangle, a rounded rectangle, a polygon, an ellipse.
• Fill fills areas outlined by curved lines with color.
• Allows you to select a color from the drawing. If you put the cursor on the desired color and press the left mouse button, the color you choose becomes the main color, and if you press the right mouse button, it becomes the background color.
• Allows you to select any required fragment of the area with the left mouse button pressed. You can do any manipulations with the selected area (move, paste into drawing or remove to clipboard, cut).

Paint 3D

This is an improved version of the graphics editor. Here you can create 3D objects in volume.  You can add three-dimensional objects to your project from the built-in library, or you can use special tools to create your own.

Windows Explorer

This program allows the user to navigate the file system of your PC and manage their folders and files. It is the main graphical shell for the user. Without this program the user would not be able to fully use the operating system.

Windows Explorer includes the following tools:

• Desktop icons and the desktop itself
• Taskbar

In the latest versions of Windows, the Start menu is used separately from Windows Explorer. If for some reason Windows Explorer hangs up, the Start menu works independently of it. This is implemented in Windows 7 and higher.

Capabilities

• Create, open, copy, delete, rename files and folders.
• Manage connected disks, flash drives, and local storages.

Recycle bin

This is an element of the graphical user interface. It is designed to delete and temporarily store deleted objects. If you right-click on the recycle bin and select "Clear Recycle Bin" - all files in the recycle bin are irretrievably deleted.

1 – Empty recycle bin

2 – Recycle bin with files

macOS

It is the operating system developed at Apple Inc. macOS operating systems are the second most common operating system after Windows. They represent about 5% of the world's active computers.

This operating system is close to Linux because the macOS kernel is based on the Unix kernel, the predecessor of Linux.

This operating system is primarily oriented towards work. A large number of handy programs and applications for work and a small number of available games prove this point.

Advantages

• Fast performance and high optimization. Apple is not only a software developer, but also a creator of system units, monoblocks, and portable computers. The company's engineers strive for the best performance of the devices.
• Convenient streamlined application management, simple user interface.

• There are few malware (viruses) if you purchase apps only from official developers. The App Store will not release a malicious application, but having an anti-virus will not be out of place.
• Useful built-in programs. macOS already includes a full-featured office for work, including a word processor, spreadsheet and presentation editor, and an app for video, graphics, and audio.
• Excellent interaction between the devices of Apple products. The iPhone smartphone, iPad tablet, and Apple Watch are the best when they interact with iMac. For example, a user can start solving a task on an iOS device (iPhone, iPad) and continue to solve it with a program installed on the iMac. This includes synchronizing information between devices or moving documents in the same cloud storage iCloud.

Disadvantages

Apple devices are shipped to the store already assembled. Important components such as the processor or RAM may be soldered to the motherboard. In case of replacement of these components, there may be problems with their recognition in the system, because the hardware identifiers of the system components are programmed in the operating system.

• A small number of entertainment applications

To run a particular game may require an emulator or installation of Windows by a second system through a special application.