Computers Technology

Difference between Logical and Physical Address in Operating System

Main Difference

While the instructions move within the computing system, they have different locations that help the user and the computer where to find them. All this activity happens due to the addresses that help with the area. The two terms getting discussed in the article are the Logical Address in Operating System and Physical Address in Operating System. They have their differences and get defined as follows; The address of something that the central processing system generates becomes known as the logical address. On the other hand, the actual address of something that the central processing system makes becomes known as the physical address.

Comparison Chart

Basis of Distinction Logical Address in Operating System Physical Address in Operating System
Definition The address of something that the central processing system generates. The actual address of something that the central processing system makes.
Nature Comes out due to the CPU Shows as the location of the logical address that is not virtual.
Space The set of all the logical addresses that the CPU generates with the program reference The set of all the addresses that get mapped to each logical address
Variation Keeps on changing Always stays the same
Relation Helps to reach the physical address. Always stays hidden from the eye of user.

Logical Address in Operating System

The address of something that the central processing system generates becomes known as the logical address. Another name used for the logical address is the virtual address because this one does not stay in the system but just acts as a guideline for the architecture to understand the positions of other things. The computer’s operating system requires some program that helps in finding the base address; this acts as a measure to find other locations within the system. Another way of explaining means the address of a memory block that it uses in the beginning.  The address that exists within the system as a base address gets added with the one generated by the central processing unit, and they both end up forming the physical address. It becomes variant from other types of addresses due to the mapping translator for most cases and address function for others. These mapping functions become a memory management unit between the CPU and the bus that carries the memory; they perform the same task when it comes to the address translation layer and the CPU. The best example of such a layer becomes the Data Link Layer that exists between the hardware and the software of the computer network. This address becomes mapped on other devices and used for various purposes time and time again. The logical memory gets erased whenever the system gets rebooted, and all the information that gets collected becomes variable within no time.

Physical Address in Operating System

The actual address of something that the central processing system generates becomes known as the physical address. It stays mapped with the help of the memory management unit and benefits the use whenever they need to find something exactly. As explained in the previous paragraph, the address that exists within the system as a base address gets added with the one generated by the central processing unit and they both end up forming the physical address. The logical address helps the system to understand the location; it should map itself to the memory to make it permanent. To do so, they required the MMU, and when the set of all the logical address become assigned to the set of all the physical address, then we call the space as physical address space. Just when a valid address gets utilized as a memory address, it is moved on the base/migration enlist. The memory-mapping equipment gadget called the memory administration unit (MMU) changes over sensible locations into physical locations. The gathering time and load-time address-restricting strategies create same intelligent and physical locations. Be that as it may, in the execution-time address-restricting plan, the smart and physical address spaces contrast. Another thing to note, that the physical address does not exist somewhere, the user does not see it with the naked eye and must depend on the pointers that show the location but not the exact code. For a system to understand instruction, the physical address becomes critical and run from the place of minimum to maximum.

Key Differences

  • The address of something that the central processing system generates becomes known as the logical address. Whereas, the actual address of something that the central processing system makes becomes known as the physical address.
  • While the logical address comes out due to the CPU, the physical address shows as the location of the logical address that is not virtual.
  • The logical address space becomes known as the set of all the logical addresses that the CPU generates with the program reference, whereas the physical address space becomes known as the set of all the addresses that get mapped to each logical address.
  • The logical addresses become visible to the user as they lie within the virtual frame, whereas the physical addresses never become visible to the user.
  • The person using a computer must first get the know-how of logical addresses to access the physical address, on the other hand, a person does not have any way of accessing the following location.
  • The physical address has all the computation done with the memory management. On the other hand, all the information within the logical address goes through the central processing unit.
  • The logical memory may keep on changing with the system, but the physical address of that object always stays the same.

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