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Comparison between real time and time sharing operating system

Protection and security

• Protection refers to a mechanism for controlling the access of program s processes, or users to the resources defined by computer system.

• The concept of protection came with the advent of multiprogramming where several processes compete for the use of CPU.

• the purpose was to confine each users program to its assigned areaof memory so that the programs cannot interface and harm each other.

• Protection in main memory is particularly important because of address translation. The purpose of protection is to allow concurrently running process to share the common physical address space.

• Protection also ensure that only process that have gained proper authorization from the operating system can operate on memory segment , the CPU, files and other resources.

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Message Delivery Protocol

Message Delivery Protocol · A protocol is a set of rules and conventions shared by communicating entities . · Message passing can be blocking or non blocking . · In blocking protocol , a sender process is blocked till the message selivered to the . in this case , sender process has guarantee that the message sent by it ie delivered before it continues its execution . A blocking protocol normally includes: 1. Blocking send : the sender process is blocked until the message is received by the receiving process or by the mailbox. 2. Blocking receive : the receiver nlocks until a message is available thus when both sender as well as receiver is blocked ,it is known as rebdevezevous . this combination allows for tight sysnchronization between process. ·...

Defination of OS(operating system) and its concepts

What do you mean by operating system? Definition : An operating system is a program that act as an interface between the user of a computer and the Computer hardware. Operating system is a first program that gets loaded into the memory through a process called booting. Concepts of operating system : · The purpose of operating system is to provide an environment in which a user can execute program in a convenient and efficient manner. · Operating system is an integrated set of program that ma...

Multi Level Queue Scheduling (MLQ)

Multi Level Queue Scheduling (MLQ) · Multilevel queue scheduling classifies the processes according to their types for example, a multilevel queue scheduling algorithm makes a common. · In this scheduling ready queue is divided into various queue that are called sub queues. A subqueue is a distinct operational queue · The process are permanently assigned to subqueues, generally based on some property of the process such as memory size,priority or process type · Each subqueue has its process sucheduling algorithm. For example interactive process at the foreground may use round robin scheduling while batch jobs at the background may use the FCFS method · For example, consider a system with four different queues 1. ...

Direct Communicationand Indirect communication

Direct Communication · Direct communication establishes a link between two processes. A communication link is a unidirectional path along which information flows. · two processes use single communication link to share information. · In this metod, there cannot be more that one link between two processes direct communication · Send and receive function used in direct communication are given below : · Send(process name , message ,(receive(process name , message) Send(A, message...

ENTERPROCESS COMMUNICATION AND SYNCHRONIZATION

ENTERPROCESS COMMUNICATION AND SYNCHRONIZATION · In multi programming environment multiple process co-exit . a single program may be broken into number of processes. · The process are classified into two categories : independent processes and cooperating processes. · An independent process is a standalone process that does not share any data with any other process. It cannot affect or be affected by the other processes executing in the system. In other words, the modification made to an independent process does not affect the functioning of other process. · A cooperating processes is a process that shares data with other processes in a system it can affect or be affectedly the other processes executing in the system · ...