How can two 16-bit registers be used to generate a 20 bit address?

The input to the address generator is two 16-bit numbers: one representing a segment and one representing an offset. The segment input will be from one of the segment registers: CS, DS, SS, ES. To generate the 20-bit address, the CPU shifts the segment 4 bits (1 hex digit) to the left and adds the offset to it.

How does MMU convert logical address to physical address?

The logical address undergoes translation by the MMU or address translation unit in particular. The output of this process is the appropriate physical address or the location of code/data in RAM. If you know that during compile time, where process will reside in memory, then an absolute address is generated.

How is a 20-bit physical address computation in 8086?

8086 has 20bit address line. So the maximum value of address that can be addressed by 8086 is 2^20 = 1MB. So 8086 can address the locations ranging between 00000 H to FFFFF H. This 1MB memory is divided into 16 logical segments, each with a memory of 64KB.

How are the segment registers used to form a 20-bit address?

5.1. A segment register changes the memory address accessed by 16 bits at a time, because its value is shifted left by 4 bits (or multiplied by 16) to cover the entire 20-bit address space. The segment register value is added to the addressing register’s 16-bit value to produce the actual 20-bit memory address.

How is a 20 bit physical address computation in 8086?

How do you calculate physical address and logical address?

To compute the physical address:

1. look up the page number in the page table and obtain the frame number.
2. to create the physical address, frame = 17 bits; offset = 12 bits; then 512 = 29. 1m = 220 => 0 – ( 229-1 ) if main memory is 512 k, then the physical address is 29 bits.

How is logical address mapped to physical address?

The logical address is mapped to the physical address using a hardware called Memory-Management Unit. The set of all physical addresses corresponding to the logical addresses in a Logical address space is called Physical Address Space.

How do you map a logical address into a physical address?

Logical Address Space is the set of all logical addresses generated by CPU for a program whereas the set of all physical address mapped to corresponding logical addresses is called Physical Address Space….Comparison Chart: