51单片机实现的4路设备工作时间计时器，有C51源码和Proteus仿真文件，还包括VB编写的上位机数据采集程序源码，通过串行口读取设备工作时间数据。-4-way MCS51 hours timer device, a C51 source and the Proteus simulation files, including VB, PC data acquisition program source code, read through the serial port device work

51单片机原理及应用－－基于Keil C与proteus 附带资料，这是第2,3,5,6章的实例-51 Microcontroller Theory and Applications and accompanying information to- Keil C with proteus, Chapter 2,3,5,6 instance