说明：  no intro
(Adder is generated and the number of devices. Arithmetic logic unit is used as a computer, perform logical operations, shift and command call. In electronics, a digital adder circuit, the addition of numbers can be calculated. In the modern computer, the adder being present in the arithmetic logic unit. Adder can be used to represent various values, such as: BCD, plus three yards, the major operator for a binary adder. Adder combinational logic circuit can also use VHDL language.)