Mca i-fundamental of computer-u-3-functions operating systems

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Functions Operating Systems

Operating SystemsCourse: MCASubject: Fundamental of ComputerUnit: 3

Operating System SoftwareOperating System (OS) Software that controls the overall operation of a computer2

2What is an operating system (OS)?Operating System Software

Software which manages the overall operation of the computer system including:hardware (CPU, RAM, I/O)securitysystem interfaceapplication interface3

3The functions of an operating system1. Manages and Interacts with Computer Hardware

2. Provides and Manages System Security

3. Provides the System Interface

4. Provides the Interface for Application Software

441. Manages and Interacts with Computer HardwareManages the CPU- What software programs the CPU works on and when

Manages RAM- What is stored in RAM and where it is stored- Virtual memory- OS will send message when RAM is full5

51. Manages and Interacts with Computer Hardware (continued)Provides the interface for storage devices and manages how data is stored on those devices- in charge of formatting disks- creates sectors and clusters- creates F.A.T. or V.T.O.C.- sends message when disk is full or there is some other problem with writing data to the disk - virtual memory - CD-ROM, DVD-ROM - Flash drive6

61. Manages and Interacts with Computer Hardware (continued)Provides the Interface for Input and Output Deviceskeyboard, mouse, printer, device drivers = software programs which allow the hardware device to be used by the operating system and by application softwareRick Graziani [email protected]

72. Provides and Manages System SecuritySingle-user Operating Systemsminimal securityuser has full authority

Server Operating Systemslogin and password capabilityprotection of users data stored on the servers central hard disk drivesprotection and security for software programsRick Graziani [email protected]

83. Provides the System InterfaceSystem Interface or shell = the interface between the user and the computer

Command Line Interface (CLI)Linux, UNIX, DOS, older OSs

Graphical User Interface (GUI)9

94. Provides the Interface for Application SoftwareOperating systems are software

Operating systems are designed and developed for a specific CPU or family of CPUsMacintosh OS: Motorola 680xx, PowerPC Gx, IntelDOS: Intel CPUsWindows 9x and XP: Intel 80386, 80486, and Pentium CPUsLinux: Intel CPUsMS NT & 2000: Intel CPUs


104. Provides the Interface for Application Software (continued)Application software is developed for an operating system

MS Word for Windows XPWindows XPIntel CPU

MS Word for the MacintoshMacintosh OS XGx CPU or Intel CPU11

11Order of Development1. The CPU

2. Other Hardware Components

3. Operating System Software

4. Application Software12

12Types of Operating SystemArchitecture of Computer SystemHardwareOperating System (OS)Programming Language (e.g. PASCAL)Application Programs (e.g. WORD, EXCEL)Operating Systema collection of programs which control the resources of a computer systemwritten in low-level languages (i.e. machine-dependent)an interface between the users and the hardwarewhen the computer is on, OS will first load into the main memoryOperatingSystemDevice configurationControls peripheral devices connected to the computerFile managementTransfers files between main memory and secondary storage, manages file folders, allocates the secondary storage space, and provides file protection and recoveryMemory managementAllocates the use of random access memory (RAM) to requesting processesInterface platformAllows the computer to run other applicationsBasic functions of the operating systemOther function of Operating Systembest use of the computer resourcesprovide a background for users programs to executedisplay and deal with errors when it happenscontrol the selection and operation of the peripheralsact as a communication link between userssystem protectionCommon Operating Systems and Their DifferencesNetwork Operating SystemUNIX / Linux / MS Windows2000 Server

Desktop Operating SystemMS Windows 9X/Me / Mac OS / DOS

Mobile Operating SystemPalm OS and Pocket PC

Different Features of Operating System

Type of Operating SystemBatch processingReal time processingTime sharing processingBatch processingJobs, together with input data, are fed into the system in a batch. The jobs are then run one after another.No job can be started until previous job is completed

Real time processingimmediate response is needed.

For example anti-missile defense systemairplane landing control systeminterrupt error in computer systemTime sharing processingEach user is given a time slice to interact with the CPU. The size of the time slice will depend on the system.Each user is served in sequence.

Special Features of OSmulti-taskingmulti-programmingparallel processingbufferingspoolingMulti-taskingto handle 2 or more programs at the same time from a single user s perceptionCPU can only perform one task at a time, however, it runs so fast that 2 or more jobs seem to execute at the same time

Multi-programming2 or more programs store in the main memory at the same timewhen one job reeds to wait (e.g. I/O operation), CPU switch to another job to executewhen the first job finishes waiting, CPU will get back the first job to executeParallel Processinguse 2 or more CPUs to handle jobscomputer networkingJob 1Job 2Job 3Job 4Job 1Job 2Job 3Job 4CPU 1CPU 2CPU 1timetimewithout multiprocessingwith multiprocessingBufferingA temporary storage area (buffers) to read data from input device or send data to the output devicekeep CPU busybecause I/O operation is slowReferenceBook ReferenceOperating System Concepts by Abraham Silberschatz, Peter B. Galvin, Greb GagneOperating System Concepts by James Lautor Peterson, Abrahamautor SilbeschatzDatabase System Concepts by Abraham Silberschatz, Henry F. Korth, S.SudarshanImage Reference