SEGMENTATION-HARDWARE

• Logical address consists of a two tuple: <segment-number, offset>
• Segment table – maps two-dimensional   user defined addresses into one-dimensional physical addresses;
•  Each table entry  of the segment table has:
•     1. base – contains the starting physical address where the segments reside in memory.
•     2. limit – specifies the length of the segment.
• Segment-table base register (STBR) points to the segment table’s location in memory.
• Segment-table length register (STLR) indicates number of segments used by a program;
• segment number s is legal if s < STLR.

ADDRESS TRANSLATION:

CPU---->(S,D)----->SEGMENT TABLE(LIMIT,BASE)----->CHECK(S < STLR)----YES--->PHYSICAL MEMORY

CPU---->(S,D)----->SEGMENT TABLE(LIMIT,BASE)----->CHECK(S < STLR)----NO--->TRAP:ADDRESSING ERROR