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MMU-memory management unit
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What is paging in an operating system?
Paging in an operating system is part of the operation of virtual memory. Physical pages of memory are being swapped back and forth for virtual pages of memory in a file on the hard disk. This swapping allows all programs to see the same memory structure (e.g. program loads at the same fixed virtual address in memory) and allows the machine to run as if it had more memory than it really does (but at a small speed penalty). Programs and utilities that are idle may stay loaded and ready to run, but paged out of physical memory until actually needed.
Why might an operating system on a virtual machine run slower than one installed directly on a PC?
any high end database(datacenter) server, exchange server, any high end appliaction server which require dedicated physical resources will work better on physical then virtual. They will work slow on Virtual servers
What is contiguous allocation?
Paging is a memory management scheme that permits the physical- address space of process to be noncontiguous.
What is the relationship between guest operating system and host operating system?
These terms are typically only applied in cases where a virtual machine is in use (a computer program that emulates a physical computer), popular examples include VMware, VirtualBox and user-mode Linux. In this case the "host" operating system is running on the physical computer and the "guest" operating system is running in the emulation software. For example I have a workstation running Debian Linux as a host operating system. When I want to compile a program for several versions of windows I can launch several instances of VirtualBox to bring up virtual machines running Windows XP, Vista and Windows 7 in both 32 and 64 bit versions as guest operating systems. This lets me easily compile the program with optimizations for each of these operating systems using a single workstation and without rebooting. Virtual machines are also common in web hosting. There are a number of hosting service providers who's business model consists entirely of selling access to user-mode Linux virtual machines. In this case the Linux guest operating system is actually running in a virtual machine under a Linux host operating system, the benefit of using virtual machines is that each customer may be given complete control over their virtual server, while the hosting company can run hundreds or even thousands of virtual servers from a handful of physical computer systems.
What are some virtual worlds that don't require email addresses?
Most today have email addresses. If you want to find one keep looking.www.poptropica.com does not require an email address to play, nor does supersecret.comProbably not. Most sites that involve any social interaction at all are going to want your email address, so they can contact you, or block you if necessary. Just create a free webmail account with Yahoo or Google Mail and use that.
What is meant by effective address in microprocessor?
Effective address is the final address generated by offsetting and indexing which is sent to the virtual translation logic. It is the address of the operand in the virtual address space of the process, but not necessarily the address of the operand in the physical address space of the computer. In the 8085, efffective/virtual address is the same as physical address, because there is no virtual addressing logic in the 8085. In the 8086/8088, effective/virtual address is the same as physical address, but only in real mode. For example, in the 8086/8088, if the EBX register contains 1000000H, then the instruction MOV EAX,[EBX+1234H] has an effective address of 10001234H.
Do I need a physical office in Malaysia?
Not necessary. Physical address is not mandatory when you have a valid virtual address that comes under the jurisdiction of Malaysian government. Virtual office concepts getting the attention nowadays.
Can physical address and virtual address be same?
your question is wrong. it should be "can physical address and logical address be same" answer is no because logical address is the combination of page number and offset whereas physical address is the combination of physical page[frame] and offset
What is the difference between virtual logical and physical address spaces?
The concept of a logical address space is simply involved the process of mapping the Logical addresses to their Physical Addresses . Logical addresses are generated by the CPU; also referred to as virtual addresses.while Physical Address is the actual address of the data stored on the physical device and mapped by MMU.
Why you need memory physical address and memory logical address?
Physical Address refers to Storage location on Physical Memory wheres Logical Addressing is used by Memory Managing Programs to refers addresses from Physical Memory and Virtual Memory.
What does physical address mean?
The physical address is the final address that is presented to the bus, at the pins of the microprocessor chip, to form the address of the desired item in memory.In the 8085, physical and effective addresses are one and the same.In the 8086/8088, the physical address is the effective address plus 16 times one of the segment registers.In higher level processors, such as the 80386 and beyond, the physical address is formed by lookup of the effective address in a page table to convert from virtual/effective address to physical, or linear, address.The effective/virtual address is the address generated by the instruction and the programmer, without regard to any underlying addressing scheme. This is the address used when considering the "programming model", in "user mode".
The virtual memory addressing capability of 80386 is?
NONE! The 80186 was an advanced version of the 8086 but did not include support for virtual memory. It had a 64K physical address space. The 80286 was the first Intel CPU to support virtual memory but it's capabilities were limited.
Which address is more important the physical address or the logical address?
In the 8086/8088 the physical address and logical address have the same importance, because they both relate to the address of the operand. It is true that the offset (logical) address is added to the segment address to determine the physical address, but the limitations of the architecture of the processor forces programmers to consider both.If you are talking about a virtual environment, however, such as in the 80286 or higher, then the logical address is more important than the physical address, because the logical address is the address of the operand, while the physical address is (somewhat) arbitrarily assigned by the operating system.
In paged system Can the logical address space b larger than physical address space?
Yes. This is the fundamental premise of paged or virtual memory - that you can have more logical memory than physical memory.
What is the difference between a physical address and a mailing address?
Real memory uses Physical addresses.These are the members that the memory chips react to on the bus. Virtual addresses are the logical addresses that nrefer to a process' address space. Thus, a machine with a 16-bit word can generate virtual addresses upto 64K, regardless of whether the machine has more or less memory than 64 KB
Is it conceivable that some operating system processes might have the entire main memory as their address space?
No, it is impossible. The operating system kernel must remain in memory at all times, including the virtual memory manager, thus no single process can physically occupy every address. Indeed, all unused physical memory is allocated to the virtual memory manager. Processes are allocated addresses within the virtual address space but some of those addresses are reserved for system use only. As such, no process can ever use the entire virtual address space let alone the entire physical address space.
What is the use of physical address in Linux?
The physical address is the memory block where things are stored during use. Linux uses physical to virtual and virtual to physical to access the Linux kernel and user work space. For more information you can check these web sites: Andries Brouwer's Linux Kernel Notes: http://www.win.tue.nl/~aeb/linux/lk/lk.html (see section 9) There is also a physical address for network cards. That address is input at the factory when the network card is manufactured. There is an online forum about How to Enter Physical Address in Wireless Network, which you can find here: http://ubuntuforums.org/showthread.php?t=494842
