Hard Disk Structure

Disk Structure The magnetic disk provides the bulk of secondary storage for modern computer systems. Each disk platter has a flat circular shape, like a CD. Common platter diameters range from 1.8 to 5.25 inches. The two surfaces of a platter are covered with magnetic material. We store information by recording it magnetically on the… Continue reading Hard Disk Structure

File Directory Structure

A directory is an object that contains the names of file system objects. The file system allows users to organize files and other file system objects through the use of directories. The structure created by the placement of names in directories can take a number of forms:  Single-level tree, Two-level tree, multi-level tree or cyclic… Continue reading File Directory Structure

Exception Handling in Java

Exception Handling It is a situation in which the program terminates abnormally. In Java, an exception is divided into two categories:- If an exception occurs at the time of run time of compilation is known as a checked exception. If an exception occurs at the time of compile-time it is known as an unchecked exception.… Continue reading Exception Handling in Java

Types of file

Types of File:- Types of the file, The files are classified into different categories as follows: The name is split into two parts-a names and an extension, The system uses the extension to indicate the type of the file and the type of operations that can be done on that file. Access Methods:- When a… Continue reading Types of file

File System Interface

File System:- The file system provides the mechanism for online storage of and access to both data and programs of the operating system and all the users of the computer system. The file system consists of two distinct parts: a collection of files, each storing related data, and a directory structure, which organizes and provides… Continue reading File System Interface

Thrashing

The system spends most of its time shuttling pages between main memory and secondary memory due to frequent page faults. This behavior is known as thrashing. A process is thrashing if it is spending more time paging than executing. This leads to: low CPU utilization and the operating system thinks that it needs to increase… Continue reading Thrashing

Demand Paging

Demand Paging A demand-paging system is similar to a paging system with swapping. Generally, Processes reside on secondary memory (which is usually a disk). When we want to execute a process, we swap it into memory. Rather than swapping the entire process into memory, it swaps the required page.  This can be done by a… Continue reading Demand Paging

Segmentation

Segmentation:- Segmentation is a memory-management scheme that supports the user view of memory. A program is a collection of segments. A segment is a logical unit such as the main program, procedure, function, method, object, local variables, global variables, common block, stack, symbol table, arrays, etc. A logical-address space is a collection of segments. Each… Continue reading Segmentation

Non-contiguous memory allocation

Non-contiguous memory allocation             In non-contiguous memory allocation, it is allowed to store the processes in non-contiguous memory locations. There are different techniques used to load processes into memory, as follows: Paging Segmentation Virtual memory paging(Demand paging)   Paging Main memory is divided into a number of equal-sized blocks, are called frames. Each process is… Continue reading Non-contiguous memory allocation

Partition Selection policy & Fragmentation

Partition Selection policy: Partition Selection policy, When the multiple memory holes (partitions) are large enough to contain a process, the operating system must use an algorithm to select in which hole the process will be loaded. The partition selection algorithm is as follows: First-fit:  The OS looks at all sections of free memory. The process… Continue reading Partition Selection policy & Fragmentation