4*4计算器 利用并行接口进行键盘扫描，自定义距阵键盘键值，实时显示输入数值，设计的计算器有差错控制功能，能正确进行两位数的加、减、乘、除运算功能。可以进行对输入数据进行编辑，有实时删除功能。配合差错控制，有错误信息提示功能。-4* 4 calculator using the keyboard scan parallel interface, a custom matrix keyboard keys, real-time display input values, there were errors in the design of the calculator control functions, can be a double-digit correctly add, subtract, multiply, in addition to computing capabilities . Of the input data can be edited, there are real-time delete function. With error control, there is an error message prompts.