foundation of computing module 3 power point

Computer System Software—Operating Systems, Basic commands in Linux /Windows, Shell scripting (bash). Computer Communications—LAN, MAN, WAN, network topology

1. MODULE 3 INTRODUCTION TO OS

2. SOFTWARE Software is a set of instructions, data or programs used to operate computers and execute tasks The two main categories of software are  Application software It is a software that fulfills a specific need or performs tasks . System software System software is designed to run a computer's hardware and provides a platform for applications to run on top of it.

3. A modern computer consists of: One or more processors Main memory Disks Printers Various input/output devices. Managing all these components require a layer of system software known as Operating System

4. Four Components of a Computer System (Computer System Structure)

5. What is an Operating System An Operating System is a program that acts as an intermediary/interface between a user of a computer and the computer hardware. OS goals: Control/execute user/application programs. Make the computer system convenient to use. Ease solving user problems. Use the computer hardware in an efficient manner.

6. Functions of an Operating System I/O Management Process Management Memory Management Storage Management Protection and Security

7. I/O Management I/O Requests are managed by Device Drivers in collaboration with some system programs inside the I/O device. The requests are served by OS using three simple segments : I/O Traffic Controller:  Keeps track of the status of all devices, control units, and communication channels . I/O scheduler:  Executes the policies used by OS to allocate and access the device, control units, and communication channels . I/O device handler:  Serves the device interrupts and heads the transfer of data.

8. Process Management A process is program in execution. Eg : A word-processing program being run by an individual user on a PC A process needs certain resources to accomplish its task. CPU time memory files I/O devices. These resources are either given to the process when it is created or allocated to it while it is running.

9. Process Management The operating system is responsible for the following process management activities : Scheduling processes on the CPUs Creating and deleting both user and system processes Suspending and resuming processes Providing mechanisms for process synchronization Providing mechanisms for process communication

10. Memory Management Main memory is the only large storage device that the CPU is able to address and access directly . For a program to be executed, it must be mapped to absolute addresses and loaded into memory . To improve both the utilization of the CPU and the speed of the computer’s response to its users, general-purpose computers must keep several programs in memory, creating a need for memory management.

11. Memory Management The operating system is responsible for the following memory management activities : Keeping track of which parts of memory are currently being used and who is using them Deciding which processes (or parts of processes) and data to move into and out of memory Allocating and deallocating memory space as needed

12. Storage management-File-System Management Files represent programs (both source and object forms) and data. Data files may be numeric, alphabetic, alphanumeric, or binary. The operating system is responsible for the following file management activities Creating and deleting files Creating and deleting directories to organize files Mapping files onto secondary storage Backing up files on stable (non-volatile) storage media

13. Storage management-Mass Storage Management Main memory is too small to accommodate all data and programs, and because the data that it holds are lost when power is lost, the computer system must provide secondary storage to back up main memory. Most modern computer systems use disks as the principal on-line storage medium for both programs and data . The operating system is responsible for the following activities in connection with disk management: • Free-space management • Storage allocation • Disk scheduling

14. Storage management-Caching: Information is normally kept in some storage system (such as main memory ). As it is used, it is copied into a faster storage system ,the cache on a temporary basis. When we need a particular piece of information, we first check whether it is in the cache. If it is, we use the information directly from the cache. If it is not, we use the information from the source, putting a copy in the cache under the assumption that we will need it again soon.

15. Protection and Security If a computer system has multiple users and allows the concurrent execution of multiple processes, then access to data must be regulated. There must be mechanisms to ensure that files, memory segments, CPU, and other resources can be operated on by only those processes that have gained proper authorization from the operating system. The timer ensures that no process can gain control of the CPU without eventually relinquishing control.

16. TYPES OF OPERATING SYSTEMS 1. Batch Operating System 2 . Multi programming OS 3. Time-Sharing Operating Systems 4. Distributed Operating System 5. Network Operating System

17. Batch Operating System This type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having the same requirement and group them into batches Examples of Batch based Operating System: Payroll System, Bank Statements, etc.

18. Multiprogramming OS Allows multiple programs to run simultaneously on a single processor

19. Time Sharing OS Each task is given some time to execute so that all the tasks work smoothly. Each user gets the time of CPU as they use a single system. These systems are also known as Multitasking Systems.

20. Multiprocessing OS More than one CPU is used for execution of processes. Each processor has its own set of registers, as well as a private or local cache. All processors share physical memory .

21. Distributed Operating System Various autonomous interconnected computers communicate with each other using a shared communication network Independent systems possess their own memory unit and CPU. These are referred to as loosely coupled systems or distributed systems. Remote access is enabled within the devices connected in that network

22. Network OS S pecialized operating system designed to manage and support networking functions, allowing multiple computers or devices to communicate and share resources over a network. It is used in servers, routers, and networking devices to facilitate data exchange and resource management Examples of Network Operating System are: Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare

23. Computer networks A computer network is a collection of interconnected devices that share resources and information. These devices can include computers, servers, printers, and other hardware. Resource Sharing Communication

24. Classification of computer networks by scale Based on the geographical area covered, computer networks are broadly categorised as: PAN (Personal Area Network) LAN (Local Area Network) MAN (Metropolitan Area Network) WAN (Wide Area Network)

25. PAN A personal area network (PAN) is a network that connects devices within a person's workspace. PANs can be wired or wireless, and are typically used to connect devices like computers, smartphones, and printers. Bluetooth Zigbee

26. LAN Are privately owned networks Is a computer network that interconnects computers within a limited area such as an office, school, hospital, laboratory etc They are used to share resources and to exchange information LANs are restricted in size Most common LAN topologies are bus, ring and star Traditional LANs operate at speeds of 10Mbps to 100Mbps. Newer LANs operate at up to 10Gbps

27. LAN

28. MAN Is a computer network in which two or more computers, communication devices or networks that are physically separated but located in the same metropolitan area are connected Is designed to extend over the entire city Eg : cable TV network in a city MANs are built by connecting many LANs. For eg , a company can use a MAN to connect the LANs in all its offices in a city MAN is wholly owned and operated by a private company or maybe a service provided by a public company

29. MAN

30. WAN Covers a large geographical area often a country or continent or even the world It is a network of networks Eg : Internet Transmission mediums used are generally public systems like telephone lines, microwave and satellite links

31. WAN

32. Internet – Network of networks Internetworking is the practice of interconnecting multiple computer networks Any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology .