Logical Address and Physical Address in Operating System

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Logical Address and Physical Address in Operating System

Logical Address and Physical Address in Operating System

You’ve probably heard about Virtual address and Physical address, but how do they differ? If not, then this article will answer your question. In addition, you’ll learn about page queues and relocatable addresses. But what is the difference between logical and physical addresses, and how do you use them? Keep reading to learn more. And if you haven’t, you should. There are many ways to access these data.

Virtual address

The virtual address of a computer is a unique binary number stored in Virtual memory. It differs from the physical address in that it enables the process to use the preferred location within the main memory. However, a virtual address requires more space than the primary memory and can result in some of the contents of the virtual memory being relegated to the internal flash drive or hard disk. In some cases, the OS can use virtual addresses to control the visibility of memory and manage the accesses to it.

To translate a virtual address to a physical address, the processor needs to read or write data at that address. The processor then extracts the virtual page number from the virtual address, adds it to a page table register, and then reads or writes data at the corresponding physical address. These operations require two physical memory accesses – one to read the data, the other to write it. However, in this case, only one of the two accesses is physical.

Physical address

The physical address in an operating system refers to the location of a computer’s memory unit. This location is stored in a table called a page-table. The page-table is maintained by the operating system and contains information about a specific page. If a page-table is not present, a program cannot access it. Instead, the operating system will prevent access to the page. To find out where a page is, look up its page-table number.

When a process is initiated, it needs to be able to access a particular address within this memory. This process will abort if it does not have a physical address. This is possible even with a single process, where several entire processes are stored within the physical memory. A PDP-11/70, for example, has 64K of logical memory, but only 22 bits of physical memory. A physical address can contain many thousands of times that amount.

Page queues

Memory pages can be analyzed if they are located within the page queues maintained by the operating system. The operating system manages the various kinds of memory pages, including inactive and active pages. These page queues are generally ignored by memory forensic tools, but they can be utilized by frameworks that incorporate memory artifacts. However, if you’re unsure of whether or not this information is useful, you should contact Andrew Doran.

The ready queue is a list of processes awaiting to be scheduled. In this queue, the code of a process may not be present in main memory. During demand paging, the OS places the process into the ready queue without allocating the page required for the process. In the case of traditional paging, the OS allocates pages to processes before placing them in the ready queue. The ready queue, on the other hand, is a list of all processes waiting to receive a main memory allocation.

Relocatable address

Relocatable address is the term used to refer to the address of an embedded program. This type of code must run on more than one address to save hardware costs. The following example shows how relocatable addresses are used. The underlying hardware requires two addresses in a single device. Relocatable addresses have two types: simple and complex. Simple relocatable addresses are based on one control section of the memory, while complex relocatable addresses are based upon several.

Relocatable address expressions depend on run-time considerations and the location of a program’s control section in memory. As a result, the OS may move a program’s logical address around the memory to accommodate its needs. Moreover, the MM will need to translate symbolic references to actual physical addresses at execution time. If a program needs to relocate, the OS must transfer the call instruction to the right address.

Absolution address

The absolute address is a unique location within the address space of a computer. This location can be a memory location, machine register, or I/O device. In computing, an absolute address is defined as the address of the first byte of memory. An absolute address is also known as an effective address. This address is computed from the base location. It is a form of the physical address that is used when accessing RAM.

The name ‘absolute’ is a fancy way to say “map.” Address binding in an operating system is the process of mapping between logical and symbolic addresses. It can occur at compile, link/load, and execution time. The absolution address is used when a program needs to find a specific location within a program’s memory. Unlike relative addresses, an absolute address can contain up to 32Kbytes of memory.

Memory space allocation

The process of allocating memory to computer programs is known as memory allocation. Memory is divided into different parts: high memory, low memory, and user processes. A computer can allocate memory in one of these parts by creating a partition for it. Partition allocation is ideal because it avoids internal fragmentation. The largest free partition becomes available for the next process when the previous process terminates. However, if a process needs more space than the partition, it can request an expansion of memory.

As the operating system allocates memory, it must have mechanisms to monitor the usage and free portions of memory. This is important because virtual memory is much smaller than physical memory. For example, a process may need a specific location in physical memory that does not exist in the virtual memory. The operating system must be able to replace what is in physical memory with data from the disk when necessary. This makes the computer system more efficient and responsive.

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