Advantages of Memory segmentation

Advantages of Memory segmentation

Addition of SS and SP to produce physical address of top of stack. 

SEGMENTATION- The memory Addressing Scheme For 8086:  

Address bus size=20 bit 

Total addressable locations=220 =1MB 

Total physical address=1MB 

By using segmentation, 1MB divided into 16 segments of each segment size 64Kb. 

1. Physical address of 8086 is 20 bit wide. So it can access 1 MB memory (220*8=1 MB or 16*64 KB). This 1 MB memory is divided into 16 Segment memories. The capacity of each memory segment is 64 KB. But 8086 can access at a time only memory segment. They are CS memory, DS memory, SS memory and ES memory. 

2. Instruction fetch operations are performed in DS memory. String operations are performed in ES memory. 

3. For the selection of each segment memory, 8086 has 4- segment registers. They are known as CS Register, DS Register, SS Register, and SS Register. The content of each segment register is known as the Base Register. 

4. BIU generates 20-bit physical Address by using segment Address and offset Address.