问题
In the 8086 architecture, the memory space is 1 MiB in size and divided into logical segments of up to 64 KiB each.
i.e. it has 20 address lines thus the following method is used:
That the data segment register is shifted left 4 bits then added to the offset register
My question is: How we do the shift operation although all the registers are only 16 bits
回答1:
Address translation is done internally by a special unit without using the registers available to user code to store intermediate results - it just fetches 16-bit values and does the translation inside - it is not reflected anywhere where the user code could observe it.
来源：https://stackoverflow.com/questions/4203921/how-is-a-physical-address-generated-in-8086