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Mahesh
Mahesh • Oct 9, 2006

Logical Vs Physical addr

What is difference between logical and physical address?
xheavenlyx
xheavenlyx • Oct 9, 2006
Ill take a shot:

Logical addrs: Its the address which we can see work on in calculations or programs at runtime. Eg, a pointer pointing to memorie.

Physical addrs: Its the actual addrss of the byte in hardware (ed, ram/rom) which is mapped by the logical addrss. After every compilation/execution the logical add can change but the physical will never.

Is it right is it right is it right?
Mahesh
Mahesh • Oct 10, 2006
Xh,you are correct but I want to know about how logical address is calculated and to what value it is added to get physical address.
xheavenlyx
xheavenlyx • Oct 10, 2006
Mahesh
Xh,you are correct but I want to know about how logical address is calculated and to what value it is added to get physical address.
You append a zero at the end of a logical addrs to get the physical addrs. Thats what is dont in a pentium type processor. Dont know about the AMD or others.
Mahesh
Mahesh • Oct 10, 2006
I don't think that by keeping 0 at last in logical address we get physical address.It varies from one process to other.Its value is added to base rregister address to get physical address.
xheavenlyx
xheavenlyx • Oct 10, 2006
No, this one I dont know😀

Give the answer in detail if you do. I really want to know.

Regards
Mahesh
Mahesh • Oct 10, 2006
I think you have this addressing in M.P. There we have this type addressing in 8086 .But this differs with addressing in our Computer Organisation.In this,
CPU generates logical address and physical address is found by adding with this with the value in a special register called relocation register.
aashima
aashima • Oct 10, 2006
Well physical address what i can recall is a part of the effective address. It is the actual path of the location of the particular data in the memory or elsewhere. Is it right?
Mahesh
Mahesh • Oct 11, 2006
Yes, you are correct.But I'm want to know more about logical address.
sandhya23
sandhya23 • Nov 12, 2008
The address generated by CPU is referred to as a logical address.
The address seen by the memory unit ,i.e,the one loaded into the memory address refister of the memory is referred to as physical address
After following ur discussion i came to know logical adder is adder generated by assembly language were as physical adder are those performed with digital gates and components...
manupep
manupep • Nov 18, 2008
Logical address and physical address comesin many situations (not only memory ,paging ..etc)

As a general talk we can say that physical address is the actual address of device, memory unit or whatever it is

Logical address is the address used by us for the better understandability of ourselves . Actual physical address format is difficult to handle (because of complex format) in our communicatin purposes . So we use logical address and mapping this logical add to physcical address.

If the doubt is still persist i will give one eg:

Everyone is aware of IP address . It is the address used to identify one machine in a network. (actually it is the address of the network card in that machine). But the actual address of the card ( the burned address by the manufacture is MAC address it is 48 bit long) .But we use IP address instead of MAC for comm. This situation IP is the logical address.

The meaning of logical , and physcical addr is situation dependent
Raviteja.g
Raviteja.g • Nov 18, 2008
excellent manu :clap:
i got a clear idea about them now😎

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