基于c8051f120的例子程序，主要进行片内DA的转换，适合初学者使用。

c8051f120是一款高速的51芯片，性能较好，但是使用的人较少，资源很缺乏。希望更多的人能使用120，能有更多更好的程序出现。-Based c8051f120 example program, mainly for the DA converter chip, suitable for beginners to use. c8051f120 chip 51 is a high speed, better performance, but using fewer people, resources are lacking. I hope more people can use 120, to have more and better programs appears.