segment register

where the segment registers reside in memory.. is it in main memory(RAM) or in the micrprocessor memory.
does segment has a fix size (64kb) or variable size...??
what is difference between paging and segmentation.??

segment registers reside in ram. They have fixed size. Now, In page concept, u have memory divided into continuous pattern and they are recognized by their few of the deciding upper bits of program counter. In case of segmentation, u have any 64k block of memory for usage. The range of addresses is decided by Base address stored in segment register. Hmmmmmm... Have you noticed d imp advantage of segmentation?? U can have one block of memory for one program data storage. Now for another program you can switch over to another block without disturbing previous data... Nice na...

nice answer chirag, one more thing qaisarpk ..segmentation is not done physically rather..memory is divided logically into segments, a perticular segment may contain one or more memory chip..or vice versa like..more then one segments may be there in a single memory chip..

microprocessor doent have any memory.the number of address lines tells us the capablity of microprocesssor to support memory for example if u hav 20 address lines then it will support or can address 2^20 b of memory ...microprocessor just have few registers which are used for diferrent purposes..like address pointer , storing oprand etc etc...basic.purpose of segmentation is to simply reduce or "fit" the address of memory location into the capacity of register (for a perticular processor).by splitting address into segment(base address) and offset(address in base)...best example is 8086..u have 20 bit total address which is split into two parts 16 bit segment and 16 bit offset..and in 8086 we hav 16 bit capacity register set..segmentation also have some more features..i hope this may have helped u to clear your ideas about segmentation..