通过四个半加器的互联，来实现四位加法器的电路结构-Through the interconnection of four and a half adder to achieve the four adder circuit

.采用原理图输入法和文本输入法实现全减器，分层设计，底层由半加器（也用原理图输入法）和逻辑门组成； 2.给出此项设计的仿真波形； 3.选择实验电路进行验证, 由发光管指示显示结果。 -. The use of schematic and text input method input method to achieve full subtracter, hierarchical design, the bottom of the half adder (also used schem