利用BIOS和DOS的中断来设计一个计算器，要求在屏幕上显示一个主菜单，提示用户输入相应的数字键，分别执行加、减、乘、除四种计算功能和结束程序的功能。-Use BIOS and DOS interrupt to design a calculator, the requirements on the screen displays a main menu that prompts the user to input the corresponding number keys, respectively, the implementation of add, subtract, multiply, with the exception of four procedures for calculating the function and the end of the function.