How does 8086 generate a 20 bit physical address example?

The 8086 addresses a segmented memory. The complete physical address which is 20-bits long is generated using segment and offset registers each of the size 16-bit. The content of a segment register also called as segment address, and content of an offset register also called as offset address.

Why does 8086 microprocessor generate 20 bit physical address?

These are Code Segment (CS) register, Stack Segment (SS) register, Extra Segment (ES) register and Data Segment (DS) register. All these are 16 bit registers. The number of address lines in 8086 is 20. So the 8086 BIU will send out a 20 bit address in order to access one of the 1,048,576 or 1MB memory locations.

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 .

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 is a 20 bit physical memory address calculated in the 8086 microprocessors?

Each Segment has a corresponding 16-bit Segment Register which holds the Base Address (starting Address) of the Segment. At any given time, 8086 can address 16-bit x 64KB = 256 KB of memory chunk out of 1MB. 8086 has 20bit address line. So the maximum value of address that can be addressed by 8086 is 2^20 = 1MB.

Why does 8086 have 20 bit address bus rather than 16 bit?

It means that in 8086, the addresses used in programs (the logical or virtual address as you call it) are 16 bits but the actual address that 8086 sends to the RAM is 20 bits. Why? Because 16 bits = 64 KB of address space where as 20 bits of address = 1 MB of memory.

How many 16-bit registers are there in 8086?

There are also four 16-bit segment registers ([CS, DS, SS, ES],have a look at the figure above) that allow the 8086 CPU to access one megabyte of memory in an unusual way.

How many 8-bit bytes are in a 20-bit address?

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 many 16-bit addresses can a 20-bit wide address bus handle?

Two 16-bit address registers are combined, where one comprises a ‘segment’ portion, and another comprises an ‘offset’ por The number of addresses uniquely accessible on any bit-parallel bus is 2 raised to the power of the bus width, in bits. So your 20-bit wide address bus (same as x86 real mode), can access 2^20 addresses.

What is the difference between a 16-bit and 20-bit processor?

You are conflating the register width with the the address bus width or addressable range. A ‘16-bit’ processor refers to how many bits of data it processes at once. The address bus width or addressable range is unrelated to this. 20 bits allows a processor to address 2^20 bytes or 1 MB of memory.