INTRODUCTION TO OPERATING SYSTEM

OPERATING SYSTEM* TOPIC 1 : INTRODUCTION TO OPERATING SYSTEMPOLISAS/JKE/EC503/Chapter1

POLISAS/JKE/EC503/Chapter1

System Computer ComponentsA computer system can be divided roughly into four components :The hardwareThe operating systemThe application programsThe users*POLISAS/JKE/EC503/Chapter1


Figure 1 : Abstract view of the components of a computer system*POLISAS/JKE/EC503/Chapter1


The hardware CPU, memory, I/O devices (provide the basic computing resources for the system)

The operating system controls and coordinates the use of the hardware among the various application programs for the various users.

The application programs word processors, spreadsheets, compilers and web browsers (defines the ways in which these resources are used to solve users computing problem.

The users human, computer, other machines.*POLISAS/JKE/EC503/Chapter1


Operating SystemDefinition

It is the main programming to control the computer. It provide user interface to translate the task of user, scheduling the tasks, organize the storage and conduct the communication with software.*POLISAS/JKE/EC503/Chapter1


The functions of operating system

Make sure all the user tasks can be done properly.Translate users command.Conduct the errors if occurred.Conduct input/output.Conduct interruption.Organize the storage.

*POLISAS/JKE/EC503/Chapter1


History Of OS*POLISAS/JKE/EC503/Chapter1


History of Operating Systems First generation 1945 - 1955Technology: vacuum tubes & plugboardsProgramming: setting some switchesProgramming language: machine languageOS: none



History of Operating SystemsSecond generation 1955 1965Technology: TransistorsProgramming: Punched cardsProgramming languages: FORTRAN & AssemblyTasks: ScientificComputer: MainframesOS: Batch system



The creation of the UNIVAC (UNIVersal Automatic Computer), the first electronic computer built for commercial use. *POLISAS/JKE/EC503/Chapter1


History of Operating Systems Early batch systembring cards to 1401read cards to tapeput tape on 7094 which does computingput tape on 1401 which prints output



*Third generation 1965 1980Technology: Integrated circuits (ICs)Programming: Punched cardsProgramming languages: FORTRAN & AssemblyTasks: Scientific & commercialComputers: IBM 360, OS: Multiprogramming/timesharingPOLISAS/JKE/EC503/Chapter1


History of Operating Systems Fourth generation 1980-PresentTechnology: VLSI (Very large Scale Ingration)Programming: High level Programming languages: C/C++, JavaComputer: PCOS: Windows, MacOS, Linux



Types Of OSBatch Operating systemA batch system is one in which jobs are bundled together with the instructions necessary to allow them to be processed without intervention.Data or programs are collected grouped and processed at a later date.Example of use :Payroll, stock control and billing systems.



Batch operating systemContains work for the system to perform without interacting with users.Jobs are grouped in batches by loading them one-by-one onto tape or disk.Enable the computer to move automatically from one job to another, without the operator (user) having to intervene.The computer would then process the jobs one at a time without further human intervention.Batch processing is still used nowadays e.g. printing thousands of mailing labels.

Memory Layout for a Simple Batch System*Figure 2The monitor is system software that is responsible for interpreting and carrying out the instructions in the batch jobs. - When the monitor starts a job, the entire computer is dedicated to the job, which then controls the computer until it finishes.



AdvantagesCan automate various aspects of job-to-job transitionReduce the amount of wasted time between jobsImprove resource utilization

Various Types of OS

Types Of OSMultiprogramming Operating System Ability to run many programs apparently at the same time.Example of Use : Mainframe systems. Each job is allocated a small amount of processing time (time slice) in turn.*POLISAS/JKE/EC503/Chapter1


Multiprogramming Operating System where more than one program can be execute at one time.Is a feature of an OS which allows running multiple programs simultaneously on one CPU.Example: You maybe typing in word, listening to music while in background IE is downloading some file & antivirus program is scanning.Actual program dont run simultaneously, but OS divides time for each program according to priorities.

Various Types of OS

*Types of OS : MultiprogrammingAs machines with more and more memory became available, it was possible to extend the idea of multiprogramming (or multiprocessing) as used in batch systems. This create a systems that would load several jobs into memory at once and cycle through them in some order, working on each one for a specified period of time. The basic physical layout of a multiprogramming system is as shown:



At this point the monitor is growing to the point where it begins to resemble a modern operating system. It is responsible for:Starting user jobsSpooling operationsIO for user jobs Switching between user jobs Ensuring proper protection while doing the above



*Types of OS : MultiprogrammingTypes of Multiprogramming Operating System:Multitasking Operating SystemA type of multiprogramming operating system which can perform several process simultaneously.The earliest multitasking OS available to home users was the AmigaOS. All current major operating system support this feature.Multi-user Operating System A multi-user operating system allows for multiple users to use the same computer at the same time and/or different times. Linux, Unix,Windows OS are some example of multiuser operating system.POLISAS/JKE/EC503/Chapter1


*Types of OS : MultiprogrammingMultiprocessing Operating SystemAn operating system capable of supporting and utilizing more than one computer.Real Time Operating SystemOften used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems. Well-defined fixed-time constraints.



Types Of OSDistributed Operating SystemProcessing is carried out independently in more than one location, but with shared and controlled access to some common facilities.Example of use : Databases e.g. libraries.*POLISAS/JKE/EC503/Chapter1


Distributed(cont)Distribute the computation among several physical processors. Loosely coupled system each processor has its own local memory; processors communicate with one another through various communications lines, such as highspeed buses or telephone lines. Advantages of distributed systems. Resources Sharing Computation speed up load sharing Reliability Communications*POLISAS/JKE/EC503/Chapter1


Distributed(cont) Requires networking infrastructure. Local area networks (LAN) or Wide area networks (WAN) May be either client-server or peer-to- peer systems.*POLISAS/JKE/EC503/Chapter1


Product Of OS*POLISAS/JKE/EC503/Chapter1

ProductVersionWindowsWindow 3.x (1990), Window NT 3.1 (1993), window 95 (1995),Windows NT workstation 4.0 (1996), Window Server 2000, Window Millennium Edition (2000), Window XP(2001), Window Vista(2006),Windows 7 (2009)LinuxRed Hat Enterprise LinuxMacMac OS X : Available only for computers manufactured by AppleSunSolaris (1992)


*OS Products : Microsoft WindowsMicrosoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft.Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs).Microsoft Windows came to dominate the world's personal computer market, overtaking Mac OS, which had been introduced previously. As of October 2009, Windows had approximately 91% of the market share of the client operating systems for usage on the Internet.The most recent client version of Windows is Windows 7.



*OS Products : Mac OS Mac OS is the trademarked name for a series of graphical user interface-based operating systems developed by Apple Inc. (formerly Apple Computer, Inc.) for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface. The original form of what Apple would later name the "Mac OS" was the integral and unnamed system software first introduced in 1984 with the original Macintosh, usually referred to simply as the System software.Mac OS X is the latest version which has superseded the "Classic" Mac OS.POLISAS/JKE/EC503/Chapter1


*OS Products : LinuxLinux is an alternativeoperating systemfor personal computers and servers. It competes mainly against Microsoft's Windows. It is based on the Unix operating system and was originally created by Linus Torvalds.Mascot/trademark: penguinLinux is a freeOpen SourceOperating System, based onUnix. It is available from many vendors with optional paid for support .POLISAS/JKE/EC503/Chapter1


Minimum RequirementsThe minimum hardware requirements for Windows XP Home Edition are: Pentium 233-megahertz (MHz) processor or faster (300 MHz is recommended) At least 64 megabytes (MB) of RAM (128 MB is recommended) At least 1.5 gigabytes (GB) of available space on the hard disk CD-ROM or DVD-ROM drive Keyboard and a Microsoft Mouse or some other compatible pointing device Video adapter and monitor with Super VGA (800 x 600)or higher resolution Sound card Speakers or headphones



Network Operating System (NOS)Short for Network operating system, NOS is the software that allows multiple computers to communicate, share files and hardware devices with one another. Some examples of network operating systems include Novell NetWare, Microsoft Windows NT, Microsoft Windows 2000, Microsoft Windows XP, Sun Solaris, Linux, etc... *POLISAS/JKE/EC503/Chapter1


Network Operating Systems Examples of network operating systems*POLISAS/JKE/EC503/Chapter1


Open Source Vs. Closed Source Software


CSSOSSDeveloped by Companies and developers work for economic purposes.Developed By Volunteers work for peer recognition. People know that recognition as a good developer have great advantageUsers may suggest requirements but they may or may not be implementedUser suggests additional features that often get implemented. Release is not too often. There may be only yearly releases.Software is released on a daily or weekly basis



CSSOSSMarket believes commercial CSS is highly secure because it is developed by a group of professionals confined to one geographical area under a strict time schedule. But quite often this is not the case, hiding information does not make it secure, it only hides its weaknessesOSSD is not market driven; it is quality driven. Community reaction to bug reports is much faster compared to CSSD which makes it easier to fix bugs and make the component highly secure Security cannot be enhanced by modifying the source code The ability to modify the source code could be a great advantage if you want to deploy a highly secure system


Components of operating system What is a kernel?The part of the operating system that resides in the main memory at all times and performs the most essential tasks, such as managing memory and handling disk input and output. In other words , kernel is a core feature of any operating system, the kernel manages communication between hardware and software.Typically, the kernel is responsible for memory management,processandtaskmanagement, anddiskmanagement.Its like a human brain that control every movements of human body*POLISAS/JKE/EC503/Chapter1


What is Shell Program?A shell is a command line interpreter that isthe interface between the user and the OS.The nameshelloriginates from shells being an outer layer of interface between the user and the internals of the operating system (the kernel).The shell: analyzes each command determines what actions are to be performed performs the actions



What is a shell?*POLISAS/JKE/EC503/Chapter1


Shell ProgramMenu-Driven SystemNo need to memorize commands. All available commands are listed Menus can be nested.Low data requirements Still used in many ATM and Point-of-Sale systems Fully GUIAlso known as Windows InterfacesMouse-driven and icon-based Windows Are allocated to the use of a particular program or process Contain a title bar, menu bar, and widgets



Some concept related to Operating SystemMulti-taskingSame concept as multiprogrammingAllows 2 or more programs at the same timeDivide the programs into active and inactive. Active application is called foreground application and inactive application is background applicationCPU does not run the programs simultaneously but manage the resources i.e. memory based on active/inactive applications



Terminology relation to OSCooperative Multi-taskingBased on multi-tasking concept, whereby foreground application controls CPU until program endsBut if program crashes/hang, OS needs to be rebootedPreemptive Multi-taskingBased on multi-tasking conceptBut if program crashes/hang, OS is able to take over CPU so other programs can be maintained



Terminology relation to OSMulti programming and also called MultithreadingExecuting many program concurrentlyOne program may execute more than one taskExample print and edit at the same timeMultiprocessingUse of 2 or more processor at the same timePrograms run simultaneouslyEach processor manage own resourcesHardware dependant esp. motherboard*POLISAS/JKE/EC503/Chapter1


Operating System StructureMonolithic SystemLayered SystemVirtual MachinesClient-Server Model*POLISAS/JKE/EC503/Chapter1


MonolithicThe oldest architecture used for operating systems is theMonolithic KernelAll functions are linked together into one huge OS binaryA monolithic system is therefore characterized by1 source code1 program generatedbut may contain concurrencyIn a monolithic architecture all components are interwoven)data is read into application memorydata is manipulatedreports may be outputdata may be saved back to the same source or different

EXAMPLE : Mainframe computer success, Linux, WindowsWhile DOS and early Windows worked poorly with multiple user



Layered Structure A technique used in designing computer software, hardware, and communications.In this case, system or network components are isolated in layers so that changes can be made in one layer without affecting the others.It is not always easy to have a truly layered architecture since some functionalities are naturally described as mutually dependent. *POLISAS/JKE/EC503/Chapter1


Virtual MachinesVirtual machine (VM) is a software implementation of a machine (i.e. a computer) that executes programs like a physical machine.A system virtual machine provides a complete system platform which supports the execution of a complete operating system(OS). *POLISAS/JKE/EC503/Chapter1


Virtual MachinesA virtual machine takes the layered approach to its logical conclusion. It treats hardware and the operating system kernel as though they were all hardware.A virtual machine provides an interface identical to the underlying bare hardware.The operating system creates the illusion of multiple processes, each executing on its own processor with its own (virtual) memory.



Client-Server ModelThe Client/Server Model is a form of distributed computing where one program (the Client) communicates with another program (the Server) for the purpose of exchanging information.



Client/Server ModelThe Client Server Model*ClientServerInternetPOLISAS/JKE/EC503/Chapter1


Subsystem of OS*POLISAS/JKE/EC503/Chapter1


Process Management

A process is a program in execution: (A program is passive, a process active.) A process has resources (CPU time, files) and attributes that must be managed.Management of processes includes:Process Scheduling (priority, time management, . . . )

Creation/termination

Block/Unblock (suspension/resumption )

Synchronization

Communication

Deadlock handling

Debugging*POLISAS/JKE/EC503/Chapter1


File Management

A file is a collection of related information defined by its creator. Commonly, files represent programs (both source and object forms) and data.The operating system is responsible for the following activities in connections with file management:File creation and deletion.Directory creation and deletion.Support of primitives for manipulating files and directories.Mapping files onto secondary storage.File backup on stable (nonvolatile) storage media.*POLISAS/JKE/EC503/Chapter1


Memory Management

Allocation/de-allocation for processes, files, I/O.Maintenance of several processes at a timeKeep track of who's using what memoryMovement of process memory to/from secondary storage*POLISAS/JKE/EC503/Chapter1


System CallsSystem calls provide the interface between a running program and the operating systemIn other words, it is a mechanism use by an application program to request service from operating systemThese calls are generally available as assembly- language instructions.Usually listed in the manuals used by assembly-language programmers. *POLISAS/JKE/EC503/Chapter1


System CallsSystem calls provide the interface between a running program and the operating systemIn other words, it is a mechanism use by an application program to request service from operating systemThese calls are generally available as assembly- language instructions.Usually listed in the manuals used by assembly-language programmers. *Continue Chapter 1POLISAS/JKE/EC503/Chapter1


System CallsProcess ManagementSignalingDirectory ManagementProtectionTime ManagementMulticore ManagementMultithreading



*a) Process managementload, execute, end, abort, create, terminate, wait ...memory allocation and reallocation

b) SignalingUse signals to keep track of events which must follow the same path of execution as depicted in figure below regardless of their type being synchronous or asynchronous. c) File managementCommon systems calls dealing with files and directories:create file, delete fileopen, closeread, write, repositionget file attributes, set file attributes

d) Device ManagementSimilarity between files and I/O devices results in similar device system calls (some OS even merges two into a combined file device structure): request device, release device read, write, reposition get device attributes, set device attributes logically attach or detach devices



*e) Information MaintenanceSystem calls for transferring information between the user program and OS:get time or date, set time or dateget system data, set system dataget process, file, or device attributesset process, file or device attributesf) CommunicationSystem calls for transferring information between the user program and OS:create, delete communication connectionsend, receive messagetransfer status informationattach or detach remote devices

THANK YOU!!!POLISAS/JKE/EC503/Chapter1


********Not until World War IIPrograms to grind out tables of sines, cosines, and logarithms.

*Transistors changed the pictureThose computers called Mainframes, with pro operators to run them.

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INTRODUCTION TO OPERATING SYSTEM

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