Demand Paging Demand paging is a technique used to implement the concept of virtual memory. It combines the concept of paging and swapping. The various processes are initially stored in secondary storage device such as disk. All the pages of a process are stored contiguously in the swap space on secondary storage. Whenever a process… Read More »
Virtual Memory – Advantages and disadvantages Virtual memory is a technique of executing program instructions that may not fit entirely in the system memory. In this scheme, the programs can be larger than the actual physical memory available. This is because of the fact that the logical memory space available to the program is totally… Read More »
Difference between Paging and Segmentation Paging Paging is the memory management scheme in which the physical memory allocated to a process is non contiguous. In this approach, physical memory is divided into fixed size blocks called frames and the logical memory is divided into fixed size blocks called pages. The size of a page is… Read More »
Paging – Memory Management Paging is the memory management scheme in which the physical memory allocated to a process is non contiguous. In this approach, physical memory is divided into fixed size blocks called frames and the logical memory is divided into fixed size blocks called pages. The size of a page is same as… Read More »
Concept of Overlays In certain situations, an application to be executed may requires more memory space than the capacity of the memory. In order to solve this problem, the concept of overlays is used. In this concept, the object program or an application consists of number of separate modules called overlays. An application may not… Read More »
Internal Fragmentation In fixed partitioning, the various partitions can be of same size or different size. Whenever a new process arrives & needs memory, it is allocated a partition large enough to hold the process. However, the size of partition may be larger than the size of the process. In such a case part of… Read More »
Partitioning is the method of dividing the main memory into certain fixed size or variable size partitions. There are various schemes that are used for partitioning. These are discussed in the subsequent sections: 1. Single partitions allocation (Monoprogramming) This method of partitioning is also known as single user contiguous allocation or single process system. It… Read More »
Swapping is a technique of removing a process from main memory and storing it into secondary memory, usually a hard disk temporarily and then bringing it back into main memory for continued execution. Swapping is a memory management technique used in multiprogramming environments which have limited memory capacity. Thus, in multiprogramming swapping may be used… Read More »
Address Binding Assigning an address to an instruction or data/variable is known as address binding. Thus address binding is a process of generating memory addresses where instructions and data of a program are to be stored. The programs are usually stored in any secondary storage device. When a program is run, the computer reads the… Read More »
Introduction A computer uses two types of storage : main memory and secondary memory. Main memory temporarily stores data and instructions to be executed by the computer. The CPU retrieves the instructions from main memory & executes them. As main memory is usually too small to accommodate all the data & programs, the information is… Read More »