How to make 20 bit address by using two 16 bit registers?

Question

IAPX88 can deal with 1 mega byte memory(20 bit addressing), now my question is how we make a 20 bit address by using two 16 bit registers.please give an example.

Answer 1

IAPX88 physical addresses are computed by taking the segment register, shifting it to the left 4 bits, and adding the offset register.

For example, the physical address in memory that code executes is (CS<<4)+IP where CS is the Code Segment and IP is the Instruction Pointer.

You can get details on the Intel 8086 wikipedia page.