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Found 989 Articles for Software & Coding
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
14K+ Views
The differences between programmed (Input/Output) I/O and interrupt-driven I/O are as follows −Programmed I/OThis I/O technique is the simplest to exchange data between external devices and processors. In this technique, the processor or Central Processing Unit (CPU) runs or executes a program giving direct control of I/O operations.Processor issues a command to the I/O module and waits for the operation to complete. Also, the processor keeps checking the I/O module status until it finds the completion of the operation.The processor's time is wasted, in case the processor is faster than the I/O module. Its module is considered to be a ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
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Before discussing about the services provided by operating system with multiple users, let us recall the services that operating system itself provides what services −Operating system servicesAn operating system provides services to programs and to the users also. It mainly provides the environment for programs to execute and makes the programming task easier.Common servicesThe common services are as follows −Program executionOperating system loads the program into CPU memory for execution and it is able to end its execution either normally or abnormally.I/O operationOperating system provides any I/O devices that are required for the program.File system manipulationPrograms need to modify the ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
32K+ Views
Multiprogramming OS is an ability of an operating system that executes more than one program using a single processor machine.More than one task or program or jobs are present inside the main memory at one point of time.Buffering and spooling can overlap I/O and CPU tasks to improve the system performance but it has some limitations that a single user cannot always keep CPU or I/O busy all the time.To increase resource utilization, multiprogramming approaches.Operating SystemJob1Job2---Job NEmpty spaceThe OS could pick and start the execution of one of the jobs in memory, whenever the jobs does not need CPU that ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
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To improve the performance and to avoid the CPU idle time the operating system uses two approaches which are explained below in detail.BufferingIt is a method of overlapping input, output and processing of a single job.After reading the data, the CPU is about to start operating on it, the input device is instructed to begin the next input immediately. The CPU and the input device are both busy. By the time the CPU is ready for the next data item the input device will have to finish its reading.The CPU then begins processing the next data while the input device ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
2K+ Views
There are different operating systems for different kinds of computers and processors. They are divided into different categories.Single processor systemSingle CPU or processor that manages the computer and it runs on a different operating system, and performs a number of tasks using one processor called a single processor system.In a single processor system different types of tasks can be performed like disk control, user control, system control etc.The figure given below depicts the single processor system −Multiprocessor systemWhen one task can be performed by using multiple processors then it is called a multiprocessor system.In a multiprocessor system a number of ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
2K+ Views
The design of the operating system should be defined by the goals and specifications which are affected by hardware and systems. Thus there would be user goals and system goals for an OS.User GoalsThe user goals or requirements should be as follows −The OS usage should be convenientShould be easy to use and easy to learnShould be safe and secure to use and information handling, and security should be robustShould be fast in response to the user requestsSystem GoalsThe system design requirements should be as follows −The OS should be easy to design, maintain and also to implement.Updates should be ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
1K+ Views
System call provides an interface between user program and operating system. It is represented as follows −When the user wants to give an instruction to the OS then it will do it through system calls. Or a user program can access the kernel which is a part of the OS through system calls.It is a programmatic way in which a computer program requests a service from the kernel of the operating system.Program executes in two modes as follows −User mode − Cannot access any hardware resources, which perform only the user operations.Kernel mode − Can access hardware resources like RAM, ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
2K+ Views
The different system calls are as follows −System calls for Process managementSystem calls for File managementSystem calls for Directory managementLet us understand them one by one.System calls for Process managementA system is used to create a new process or a duplicate process called a fork. The duplicate process consists of all data in the file description and registers common. The original process is also called the parent process and the duplicate is called the child process.The fork call returns a value, which is zero in the child and equal to the child’s PID (Process Identifier) in the parent. The system ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
878 Views
System call mechanism is one of the techniques by which a user program requests for services from the kernel. System calls always provide an interface to the services that are available by an operating system.Let us see the step by step explanation of system call mechanism as given below −Step 1 − A process that is running a user program in user mode wants to execute a read instruction a file and it has to execute a trap instruction to transfer control to the operating system.Step 2 − The read operation in system call has three parameters which are as ... Read More
![Bhanu Priya](https://www.tutorialspoint.com/assets/profiles/314653/profile/60_78287-1615027882.jpg)
12K+ Views
Locality of reference refers to the tendency of the computer program to access the same set of memory locations for a particular time period. The property of Locality of Reference is mainly shown by loops and subroutine calls in a program.On an abstract level there are two types of localities which are as follows −Temporal localitySpatial localityTemporal localityThis type of optimization includes bringing in the frequently accessed memory references to a nearby memory location for a short duration of time so that the future accesses are much faster.For example, if in an instruction set we have a variable declared that ... Read More