说明：  采用 Lineto 和 moveto函数编写的示波器程序，能够显示四路波形，配有各种调节按钮，界面虽然简单，但是对于初学者来说，是一个很好的实例程序。
(The oscilloscope program written using Lineto and moveto function can display four waveforms, with various adjustment button, the interface is simple, but for beginners, is a good example of the program.)