1.X86系统的寄存器集
accumulators：
Intel 8086/80286: one word (16 bit) accumulator,named AX (high order byte of the AX register is named AH and low order byte of the AX register is named AL) ;
Intel 80386: one doubleword (32 bit) accumulator, named EAX (low order word uses the same names as the accumulator on the Intel 8086 and 80286 [AX] and low order and high order bytes of the low order words of four of the registers use the same names as the accumulator on the Intel 8086 and 80286 [AH and AL])
data registers：
Intel 8086/80286: one word (16 bit) accumulator,named DX;
Intel 80386: one doubleword (32 bit) accumulator,named EDX
base registers:
Intel 80x86: 6 dedicated segment registers: CS (code segment), SS (stack segment), DS (data segment), ES (extra segment, a second data segment register), FS (third data segment register), and GS (fourth data segment register)
program counter(instruction pointor register):
Intel 8086/80286: 16-bit instruction pointer (IP) ;
Intel 80386: 32-bit instruction pointer (EIP)
