How is the physical memory address calculated in the 8086 processor?

How is the physical memory address calculated in the 8086 processor?

I learnt that the physical address is calculated by shifting the segment address (16-bit) left 4 times and adding it with the 16-bit offset address. The memory in the 8086 architecture is 1M.

How do we calculate physical address of memory?

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 does the 8086 system store 20-bit address in a 16-bit register?

1 Answer. Each 20-bit physical address slot holds one 8-bit byte. A 16-bit word takes 2 consecutive address slots. Physical addresses (in original 8086) are 20 bits wide, data is (up to) 16 bits wide.

How is a 20-bit address obtained if there are only 16-bit registers?

The problem with the 8088 computer is that there are only 16-bit registers, so that something extra must be done to generate a 20-bit address. 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 do you find the 20 bit physical address?

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. A common combination for segment and offset is the CS and IP registers: together they indicate the address of the next instruction.

How do you calculate physical address from logical address in segmentation?

If it is, add offset + base address for the physical address. If it is not, a segment fault will occur. a) (0, 198) we will check 198< 248, which is true so we will calculate Physical address = 660+ 198 = 858. b) (2, 156) we will check 156< 198, which is true so we will calculate Physical address = 222+ 156= 378.

How do you calculate effective address and physical address in 8086?

Physical address can be calculated as DS * 10H + BX. In this mode, the operand address is calculated using one of the base registers and an 8 bit or a 16 bit displacement. This instruction moves a byte from the address pointed by BX + 4 in data segment to CL. Physical address can be calculated as DS * 10H + BX + 4H.

How do you find the 20-bit physical address?

So, Physical Address = Base Address + Offset. Suppose the Data Segment holds the Base Aaddress as 1000h and the data you need is present in the 0020h memory location (Offset) of the Data Segment. The calculation of the actual address is done as follows. So the actual address turns out to be 10020h.

How convert 16 bit address to 20-bit address explain with the help of example?

First, we shift the first address by four bits to the left: 7 2 3 A 0 which is called the base. Then, we add the the second address: 0 0 0 5 which is called the offset. The result of this operation is a new 20-bit address: 7 2 3 A 5 .

What is physical address in microprocessor?

In computing, a physical address (also real address, or binary address), is a memory address that is represented in the form of a binary number on the address bus circuitry in order to enable the data bus to access a particular storage cell of main memory, or a register of memory-mapped I/O device.

How do you convert physical address to logical address?

Divide physical memory into fixed-sized blocks called frames (size is power of 2, between 512 bytes and 8192 bytes). Divide logical memory into blocks of same size called pages. Keep track of all free frames.