c51 的8255键盘及led扩展，对初学单片机的的来说是不错的资料-c51 keyboard and led the 8255 expansion of the right SCM beginner is a good information

电脑数字小键盘用在C51单片机上的驱动软件-Computer numeric keypad with the driver software on a C51 microcontroller

单片机C51闭环温控系统，通过键盘输入温度，系统自动进行温度调节，该文件具体讲述了实现各个分块的思路。-C51 MCU closed-loop temperature control system, through the keyboard input temperature, automatic temperature control system, the document describes the specific implementation of each sub-block ide

矩阵键盘+液晶显示，C51，很不错的小程序，供初级使用(Matrix keyboard + liquid crystal display, C51. Good small programs for primary use.)