Segmentation

* Memory management scheme that supports user view of memory

* A program is a collection of segments

- A segment is a logical unit such as.. Main program, Procedure, Function, Method, Object, Local variables, global variables, Common block, Stack, Symbol table.....

Main Program

Subroutine

Stack

Symbol table

Physical memory space

- Logical address consists of a two tuple : Segment-number, offset

- Segment table

* Maps two-dimensional physical addresses

* Each table entry has

+ Base - contains the starting physical address where the segment resides in the memory

+ Limit - specifies the length of the segment

* Segment-table base Register (STBR) : 메모리에 있는 segment table의 위치를 가리킴

* Segment-table Length Register(STLR) : 프로그램에 의해 사용된 세그먼트들의 수를 나타냄 (세그먼트 넘버 s는 s<STLR일 때 유효하다)