包含按键扫描，字符处理到数学运算、功能函数等从初级到深入的各类源程序。

代码说明：

包含按键扫描，字符处理到数学运算、功能函数等从初级到深入的各类源程序。- Contains the pressed key scanning, the character processes primarily to mathematics operation, the function function and so on from to the thorough each kind of source program.