程序从标准输入读入数据输出至指定输出文件，并根据输入的要求同步写或异步写。 此程序的主体在于read和write函数的配合使用以实现将从输入文件读入的数据复制到输出文件。-procedures from the standard input output read data to the designated output file, and in accordance with the requirements of the importation of synchronous or as

此程序为一可编程并行接口实验源程序，通过此实验可掌握8255方式0的工作原理及使用方法。编程从8255C口输入数据，再从A口输出。-procedure for a programmable parallel interface experiment source, the passage of this experiment can seize 8,255 0 means the working principle and methods of use. Programming from the