说明：  这个程序犀利了，是我的得意之作，他在ucOS51上增加了一个shell程序，希望对大家有用，即使没有商业应用，希望大家也自己做做，因为真的很有意思，shell是linux下的终端交互，在51上实现，不是很神奇的事情吗？
(This procedure has been sharp, it is my finest creations, he added ucOS51 a shell procedure, useful for all of us hope that, even in the absence of commercial applications, I hope everyone doing their own, because it is really very interesting, shell is under linux interactive terminals in 51 to achieve, is not very magical things?)