Computer Basics and Software Classification

P resentation on Click to edit Master title style Operating System Course: B.Sc.(G) 3rd Semester Paper: DSC-1C/2C/3C Presented By----------------- Prasenjit Mura State Aided College Teacher of Bajkul Milani Mahavidyalaya Dept. of Computer Science 1

Click to edit Master title style A computer is a digital electronic device which can accept, store, retrieve and process data, gives corresponding accurate result with enormous speed. Define Data, Information and Program. Data: Meaningless raw facts which are given to a computer to solve a particular task. Ex. - 18, Contai, Rice etc. Information: Information means processed data which are meaningful. It provides knowledge or insight about a certain matter. Ex. - Ram is 18 Years old. Program: A set of instructions, written in specific sequence to solve a particular problem. Components of a Computer: Computers have two basic types of component- 1. Hardware 2. Software Hardware: Computer System consists of some electronic, electrical, magnetic, mechanical or optical components that we can touch are called hardware. In other word, the physical components of a computer are called hardware. Ex- CPU, Hard disk, Key board, Mouse, Printer etc. Software: A set of Programs is called software. Note: Computer hardware components are activated and controlled with the help of computer software. What is Computer? 2

Classification of Software. Click to edit Master title style Computer Software Utility Software Application Software System Software Software package User written software Operating System Language Processor Translator Editor Linker Debugger Locator Loader Compiler Assembler Interpreter 3

System Software: Click to edit Master title style System software are programs used to handle computer hardware and to execute application program. Ex- Language processor, operating System. Application Software: Application software are programs used to solve specific task in day-to-day life, like banking railway reservation, photo editing, word processing etc. Ex. MS word, Photoshop, Media Player etc. Utility Software: The software are automatically installed with operating system to server general application. Ex. Paint, Calculator, Notepad etc. 44

Click to edit Master title style Language, classification of language. Language: The notation used to write a program in computer is called a programming language. Language Low level Language High Language Assembly language Machine Language 55

Click to edit Master title style High-level language: The language where programs are written by English word and mathematically symbol, they are compiled into assembly language by compiler. This type of language is machine independent. Low-level language: The low-level language are either machine code or are very close them. This type of language is corresponds directly to a specific machine. i. Machine language: A computer understand information Composed of only Zeros and ones and hence it used binary digits for its operation. The computers instruction are coded and stored in the memory in the form of 0 s and 1 s language which forms only 0 and 1, is called machine language. ii. Assembly Language: The writing of programs in machine language is very difficult tiresome and boring job for a programmer. Programs can easily be written in alphanumeric symbols instead of 0 s and 1 s, such symbols are known as mnemonics. For example ADD for addition, SUB for subtraction, CMP for comparison etc. A language Consists of Mnemonics is called assembly language. 66

Definition Click to edit Master title style An operating system acts as an intermediary between the user of a computer and computer hardware. It provides environment in which a user can execute programs conveniently and efficiently. An operating system is concerned with the allocation of resources and services, such as memory, processors, devices, and information. The operating system correspondingly includes programs to manage these resources, such as a traffic controller, a scheduler, a memory management module, I/O programs, and a file system. 77

Abstract view of Components of a Computer System or position of OS Click to edit Master title style in Computer System or Operating System as a user Interface. Hardware: The hardware consists of memory, CPU, ALU, I/O devices and storage device. Operating System: The OS manages H/W and S/W resources and allocate various application programs for the various users. Language Processor and Application Programms: Language processors convert high level or assembly into Computer understandable machine language and application programs performs specific task. User: The end Users operate on computer system. 88

Function of Operating system. Or Click to edit Master title style Operating system Is necessary in every computer system. Or Operating system is Called as a resource Manager Why? Process Management: The operating system handled all the processes those are given by the user or the process those are system s own process. Memory Management: OS also manages the memory of computer system by providing the memory to the process and deallocate the memory from the process when the process completed. File Management: OS responsible for; - creation or deletion of files, - Creation or deletion of directories, - file and directory manipulation,- backing or storing files etc. I/O device Management: co-ordination and assignment of different I/O devices While one or more being executed. 99

Click to edit Master title style Secondary storage management: system program like compilers, debuggers, editors, linkers etc. are stored on the disk only and are loaded into the Ram, when required. Most of the time required Hard disk only. It is the job of OS to swap-in or Swap-out Such Program. Security Management: Security or system protection refers to a mechanism for controlling the accesses to computer resources by various users and processes. Since there will be multiple users and hence multiple process being executed, so there is need of protection from each other and also protection of OS from the user processes. This is the job of OS. Command Interpretation: It is defined as an interface between the user and the OS. It means interpreting users command and direction of process and convert computer understandable form. 1010

What are the basic services provided by the Operating System? Click to edit Master title style Program Execution: The system must be able to load a program into memory and run the program. I/O operations: All the program dealing with I/O operation relating to specific devices are to be dealt with OS. File system implementation/manipulation: file system is of particular interest. Programs need to read and write files. File can be labeled by their unique name. Resource allocation: When the number of users are more one, multiprogramming (resource sharing) has to be implemented. Many different types of resources are managed by the OS. 1111

Click to edit Master title style Error detection: There are various types of errors that occur when the process is running. Error may be between CPU and memory or between CPU and I/O. OS handles these errors and gives information to the user. Communication: Process running on the same computer or different computers need to communicate with each other to exchange information. By providing these service OS relieves the user of the worry of passing message between processes. Protection: In multi-user environment, protection of valuable resources OS plays an important role. Accounting: The record keeping works as to which resource has been utilized by which process and for how long is being cared by OS. 1212

Click to edit Master title style Measuring system performance / efficiency of a system. Efficiency of an operating system is calculated by a combination of two different parameter or factor as follows- Throughput: Number of process that are completed their execution per unit time is called throughput. Higher is the throughput, better it is. If a system is able to complete n process in t unit time, so the throughput n/t process /unit time. Turnaround time: How long a process takes to execute. It is calculate as the interval from time of submission of a process (i.e process creation) to the time of completion. TAT=- Process finished time-Process arrival time. 1313

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