Logical address and physical address

\( \newcommand\) • • • Segmentation in Operating System A process is divided into segments. The segments are not required to be of the same sizes. There are 2 types of segmentation: • Virtual memory segmentation Each process is divided into a number of segments, not all of which are resident at any one point in time. • Simple segmentation Each process is divided into a number of segments, all of which are loaded into memory at run time, though not necessarily contiguously. There is no simple relationship between logical addresses and physical addresses in segmentation. A table stores the information about all such segments and is called Segment Table. Figure \(\PageIndex\): Translate Logical Address to Physical Address. ( Address generated by the CPUis divided into: • Segment number (s):Number of bits required to represent the segment. • Segment offset (d):Number of bits requiredto represent the size of the segment. Walking through the diagram above: • CPU generates a 2 part logival address. • The segment number is used to get the Limit and the Base Address value from the segment table. • If the segment offset (d) is less than the Limit value from the segment tablethen • The Base Address returned from the segment table,points to the beginning of the segment • The Limit value points to the end of the segment in physcial memory.

Through logical address the system identify a network (source to destination). after identifying the network physical address is used to identify the host on that network. The port address is used to identify the particular application running on the destination machine. Logical Address: An IP address of the system is called logical address. This address is the combnation of Net ID and Host ID. This address is used by network layer to identify a particular network (source to destination) among the networks. This address can be changed by changing the host position on the network. So it is called logical address. Physical address: Each system having a NIC(Network Interface Card) through which two systems physically connected with each other with cables. The address of the NIC is called Physical address or mac address. This is specified by the manficture company of the card. This address is used by data link layer. Port Address: There are many application running on the computer. Each application run with a port no.(logically) on the computer. This port no. for application is decided by the Karnal of the OS. This port no. is called port address. Difference between logical address and logical address space? Logical address is the address generated by the CPU (from the perspective of a program that is running) whereas physical address (or the real address) is the address seen by the memory unit and it allows the data bus to access a particular memory cell in the main memory. A...

The term Memory can be defined as a collection of data in a specific format. It is used to store instructions and process data. The memory comprises a large array or group of words or bytes, each with its own location. The primary motive of a computer system is to execute programs. These programs, along with the information they access, should be in the main memory during execution. The CPU fetches instructions from memory according to the value of the program counter. To achieve a degree of multiprogramming and proper utilization of memory, memory management is important. Many memory management methods exist, reflecting various approaches, and the effectiveness of each algorithm depends on the situation. Here, we will cover the following memory management topics: • What is Main Memory? • What is Memory Management? • Why memory Management is required? • Logical address space and Physical address space • Static and dynamic loading • Static and dynamic linking • Swapping • Contiguous Memory allocation • Memory Allocation • First Fit • Best Fit • Worst Fit • Fragmentation • Internal Fragmentation • External Fragmentation • Paging Now before, we start Memory Management let us know what is main memory. What is Main Memory? The main memory is central to the operation of a Modern Computer. Main Memory is a large array of words or bytes, ranging in size from hundreds of thousands to billions. Main memory is a repository of rapidly available information shared by the CPU and I/O de...

Difference between Logical Address and Physical Address in Operating System Logical and physical addresses are important terms. The logical address is rendered by CPU while a program is executed, whereas the physical address directs to a location in the memory unit. Let’s figure out some major differences between logical and physical addresses. Ultimate Guide to Kickstart your GATE Exam Preparation What is a Logical Address? An address induced by CUP when the program is executing is known as a logical address. It is assumed as a virtual address because it doesn’t have a physical presence and that is why it is also known as a virtual address. A logical address may be distinct from a physical address because of the operation and process of an address translator. What is a Physical Address? An address that helps in identifying the physical location of needed data is known as a physical address. We cannot use the physical address directly, to use it we have to access it by its corresponding logical address. We can use the physical address space term for all the physical addresses corresponding to the logical addresses. Difference between Logical Address and Physical Address in Operating System S.No Logical Address Physical Address 1 Logical address is rendered by CPU. Physical address is like a location that is present in the main memory. 2 It is a collection of all logical addresses rendered by the CPU. It is a collection of all physical addresses mapped to the connected logi...

Let us try to deeply understand, why IP address is known as “Logical” while, MAC Address is known as “Physical” address. The IP address and the MAC address are both used for addressing and identifying devices on a computer network, but they serve different purposes and operate at different levels of the network stack. An IP address is a logical address because it is assigned by a software protocol, such as the Internet Protocol (IP), to uniquely identify a device on a network. It is designed to work at the network layer of the network stack, which is responsible for routing packets across different networks. IP addresses are used to provide logical addressing and routing functionality, allowing devices on different networks to communicate with each other. On the other hand, a MAC address is a physical address because it is hardcoded into the network interface card (NIC) of a device by the manufacturer. It is designed to work at the data link layer of the network stack, which is responsible for transmitting data between devices on the same network. MAC addresses are used for low-level communication between devices on the same network, such as Ethernet LANs. The term “physical address” refers to the fact that the MAC address is tied to the physical hardware of the network interface card, which is a physical component of the device. The MAC address uniquely identifies the NIC and is used to ensure that data is transmitted to the correct destination on the same physical networ...

( Internet Protocol address) The address of a connected device in a TCP/IP network, which is the worldwide standard both in-house and on the Internet. Every desktop and laptop computer, server, scanner, printer, modem, router, smartphone, tablet and smart TV is assigned an IP address, and every packet (Web, email, video, etc.) traversing an IP network contains a source IP address and a destination IP address. Public and Private Addresses For homes and small businesses, the entire local network (LAN) is exposed to the Internet via one public IP address. Large companies may have several public IPs. In contrast, the devices within the local network use private addresses not reachable from the outside world, and the router enforces this standard. The same private address ranges are used in every network, which means every computer within the company has the identical private IP address of a computer in thousands of other companies. See Logical vs. Physical An IP address is a logical address that is assigned by software residing in the router or server, and that logical address can change from time to time. For example, a laptop is likely to be assigned a new IP when it starts up in a different hotspot (see Static and Dynamic IP Network infrastructure devices such as servers, routers and firewalls are assigned permanent "static" IP addresses. A user's machine can also be assigned a non-changing static IP by the network administrator; however, it is generally configured to accep...

Advertisements The address generated by CPU is called a logical address, and the address seen by the memory unit is called a physical address. The physical address is loaded into the memory-address register of the memory. Logical vs. Physical Address The compile-time and load-time address binding generate identical logical and physical address due to static binding techniques. The logical address and physical address are part of the runtime address binding technique. They are different from each other. The logical address is also known as a virtual address. The virtual addresses are pages of fixed or variable size and the physical address are called frames that are part of memory hardware (RAM). Memory Relocation and Address Spaces Set of all logical addresses by a program is called its logical address space. Set of all physical addresses corresponding to physical address is called physical address space. The run-time mapping is done by hardware called the memory-management unit (MMU). Advertisements For example, if base = 15000, then access to location 540 is mapped to 15540 (physical address). MS-DOS with an intel 8086 used 4 such relocation registers to run processes. The program uses the logical address to do all memory operations using virtual address e.g 540 without knowing the physical address e.g 15540. Only when used as a memory address, it is relocated using relocation register and reference is completed by fetching physical memory address. The final location of ...

In this tutorial, we will be covering the concept of logical and physical address space. The address that is generated by the CPU is commonly referred to as the Logical Address. It is basically a virtual address. The logical address is basically the address of an instruction or data used by any program. The set of all logical addresses that are generated by any program is referred to as Logical Address Space. The address that is loaded into the memory-address register of the memory is commonly referred to as a Physical address. A physical address cannot be accessed by the user directly but the user can calculate the physical address with the help of a Logical address. The user's program mainly generates the logical address and the user thinks that the program is running in this logical address but the program mainly needs physical memory in order to complete its execution. The set of all physical addresses corresponding to the Logical addresses is commonly known as Physical Address Space. Memory Management Unit(MMU) in OS It is a hardware device that does the run-time mapping from the virtual address to the physical address. It is located within the Central Processing Unit. Let us understand the concept of mapping with the help of a simple MMU scheme and that is a base-register scheme. In the above diagram, the base register is termed the Relocation register. The relocation register is a special register in the CPU and is used for the mapping of logical addresses used by a...