Paper Code : MCA 311 Course: MCA 2nd Year,(3 rd Semester) Faculty: Mrs. Pooja Pandey. Mrs. Rama...
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Transcript of Paper Code : MCA 311 Course: MCA 2nd Year,(3 rd Semester) Faculty: Mrs. Pooja Pandey. Mrs. Rama...
Paper Code : MCA 311Course: MCA 2nd Year,(3rd Semester)Faculty: Mrs. Pooja Pandey. Mrs. Rama Chaudhary
Current Technology
Personal digital assistant (PDA)
Mobile phone / PDA
video phone
LaptopBest friend
Is an OS essential?
Not Necessary If OS is not available, application
code is responsible of conducting duty of OS( Memory Management, Resource Allocation etc)
It is Good Approach to have OS, this will allow individual programs to perform specific task not to waste time in writing code for management task i.e.Resource AllocationMemory managementManage I/O
Career Avenues
Software Developer, System Architect, Program Manager
RedHat, IBM, Microsoft, Google, Apple, Ubuntu, Solaris
Courses available on Unix, Linux, are major widely recognized by IT industry..
Career Avenues….
Advantages Good salary Innovation @ work
Disadvantages
ERROR, can not afford !!!
Emerging trend of free OS like Linux, Google Chrome has increased professionals demandMobile devices i.e Cell phones, Tablets & Phablets have revolutionized demand of OS, Product i.e. Google’s Android , Apple’s iOS, Blackberry’s RIM are offering huge opportunity for developers.
Learning Outcomes
Define Operating System Functions of Operating System. Evolution of Operating System. System Components. Understanding of OS Structure. Operating System Services. System Calls. System Programs. Virtual Machine
What is a system call?
It provide the interface between a running program and the operating system
Example:- writing a simple program to read data from one file and copy that to another file
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Processor ModesModern processors typically can operate in 2 modes:
"user mode" and "kernel mode " . User mode
processor executes normal instructions in the user's program.
Kernel mode processor executes both normal and privileged instructions
Processor can access additional registers and memory address space that are accessible only in kernel mode
Types of system calls
Process control File operationsDevice manipulationInformation maintenanceCommunications
Process control:-End, abortLoad, executeCreate process, terminate processGet process attributes, set process attributesWait for timeWait event, signal eventAllocate and free memory
File Management:-Create file , delete fileOpen , closeRead , write , repositionGet file attributes , set file attributes
Device management:-Request device , release deviceRead , write , repositionGet file attributes , set file attributesLogically attach or detach device
Information maintenance:-Get time or date , set time or dateGet system data , set system dataGet process, file, or device attributesSet process , file or device atributes
Communication:-Create , delete communication connectionsSend , receive messageTransfer status informationAttach or detach remote devices
System calls System calls to the operating system are
further classified according to the types of call:-
Normal TerminationAbnormal terminationStatus RequestResource RequestInput\ Output Request
System ProgramsSystem programs provide a convenient
environment for program development and execution
Some of them are simply user interfaces to system calls. The can be divided into:File manipulation Status informationFile modificationProgramming language supportProgram loading and executionCommunicationApplication programs
System ProgramsFile management: – Create, delete, copy, rename, print, dump, list,
and generally manipulate files and directoriesStatus information:-
Some ask the system for info - date, time, amount of available memory, disk space, number of users
Others provide detailed performance, logging, and debugging information
System ProgramFile modification:-Several text editors may be available to create
and modify the content of files stored on disk or other storage devices
Programming language support:- Compilers , assemblers , debuggers and
interpreters for common languages(C, C++…..) are often provided to the user with the OS.
System ProgramProgram loading and execution:-Once a program is assembled or complied , it
must be loaded into memory to be executedCommunication:-These program provide the mechanism for
creating virtual connections among processes, users , and computer system(allow user to send message, transfer file from one machine to another)
Application program:-
Virtual MachinesA virtual machine takes the layered
approach to its logical conclusion. The fundamental idea behind a virtual
machine is to abstract the hardware of single computer into several different execution environments , thereby creating the illusion that each separate execution environment is running its own private computer.
By using CPU scheduling and virtual memory techniques, an operating system can create the illusion that a process has its own processor with its own (virtual ) memory
Virtual Machines (Cont.)
(a) Non virtual machine (b) virtual machine
Non-virtual Machine Virtual Machine
Advantages/Disadvantages of Virtual Machines
The virtual-machine concept provides complete protection of system resources since each virtual machine is isolated from all other virtual machines. This isolation, however, permits no direct sharing of resources.
A virtual-machine system is a perfect vehicle for operating-systems research and development. System development is done on the virtual machine, instead of on a physical machine and so does not disrupt normal system operation.
The virtual machine concept is difficult to implement due to the effort required to provide an exact duplicate to the underlying machine