Skip to main content

Logical VS Physical Address Space In Operating System

Basically an address generated by the CPU is commonly referred  as a logical address, whereas an address seen by the memory unit is commonly referred as a physical address.The compile-time and load-time address-binding methods generate identical logical and physical addresses. However, the execution-time address binding scheme results in differing logical and physical addresses. In this case, we usually refer to the logical address as a virtual address.


The set of all logical addresses generated by a program is a logical address space. The set of all physical addresses corresponding to these logical addresses is a physical address space. Thus, in the execution-time address-binding scheme, the logical and physical address spaces differ. The run-time mapping from virtual to physical addresses is done by a hardware device called the memory-management unit (MMU).


The user program generates only logical addresses and thinks that the process runs in locations 0 to max. However, these logical addresses must be mapped to physical addresses before they are used. The concept of a logical address space that is bound to a separate physical address space is central to proper memory management.



Logical Address is generated by CPU while running of program. The logical address is virtual address. This address is used as a reference to access the physical memory location by CPU. The hardware device called Memory-Management Unit is used for mapping logical address to its corresponding physical address. Physical Address is a physical location of required data in a memory. The user never directly deals with the physical address. For access it uses its corresponding logical address. The user program generates the logical address and thinks that the program is running in this logical address but the program needs physical memory for its execution. So the logical address must be mapped to the physical address by MMU before they are used.


In other  words the physical address space in a system can be defined as the size of the main memory in a system. It is an important task to always compare the process size with the physical address space. The process size must be less than the available physical address space. Logical address space can be defined as the size of the process. The size of the process should be less enough so that it can reside in the main memory.


Share, Follow and please comment if you find anything incorrect or to share more information about the topic discussed above.

Labels:

Comments

Post a Comment

Please comment.

Popular posts from this blog

Process & Its state And process control block :-

                ⇰  PROCESS :- A process can be thought of as a program in execution. Means when any program is executed it becomes process. A processwill need certain resources such as CPU time , memory, files and I/O devices to complete its task. These resources are allocated to the process either when it is created or at the time of execution.             A process is the unit of work in most systems. A system consistes of a collection of processes. All these processes may execute concurrently. Traditionally a process contained only a single thread. Most modern operating ststems now supports processes that have multiple threads.         The operating system is responsible for several important works of process management as - the creation and deletion of process, the schrduling of process, communication and deadlock handling of process. Process is broudly divided into two ...
Post a Comment
Read more

Process Scheduling And Types of Process Schedular :-

        ⇰ PROCESS SCHEDULING Process Scheduling  is a task  of Operating System that schedules processes of different states like new, ready, waiting, terminated  and running.This scheduling helps in allocation of CPU time for each process, and Operating System allocates the CPU time for each procss. And the process scheduling plays important role to keep the CPU busy all the time.  ⏩   Followings are some objectives of Process Scheduling :-  i > To increase the amount of users within acceptable response times.  ii > To maintain the balance between response and utilization of system. iii > To decrease the enforce priorities and  give reference to the processes holding the key resources.      ⇰  PROCESS SCHEDULAR A scheduler carries out the pro cess scheduling work. Schedulers are often implemented so they keep all computer resources busy and  allows multiple users to shar...
8 comments
Read more

Definition of Stack and its algorithm with working process(data structure)

                  Stack                           A Stack is  an ordered collection of items where the addition of items and the removal of existing items always takes place at the same end. This end is commonly referred to as the “top". * working method of stack :- i> Initially top=-1 ii> By increasing top pointer we can insert element    in the stack. iii> when top=size of stack-1  then stack is full. iv> By decreasing the top pointer we can remove   the   element from stack. v> when top=-1 then the stack is empty. figure shows run time stack * The fundamental operations which are possible on a stack are:-         1. push operation (insertion).    2. pop operation (deletion).    3. peep opetation(extract informat...
2 comments
Read more