RFC1939-POP3协议详解，开发收发邮件程序必备-Detailed RFC1939-POP3 protocol to develop the necessary procedures to send and receive e-mail

POP，即像素奇偶性算法，新的一种对位图空域信息隐藏算法。自己的一点理解。-POP, the pixel parity algorithm, a bitmap airspace information hiding algorithm. Their own little more understanding.

利用AT89C51实现简易电子琴的低8音和高8音的发声，能简易弹出曲目-Use simple keyboard AT89C51 achieve low 8 high 8 sound audible tones can be simple pop tracks