说明：  HD7279(c语言)驱动 程序作用：测试Sage Tech.开发板（MCP300）中hd7279键盘显示芯片是否能正常工作 程序功能：按下1号键显示0、1、2、3，按下2号键显示c、d、e、f，按下3号键显示4、5 、6、7 按下4号键显示8、9、a、b，按下0号键点亮4个LED灯
(HD7279 (c Language) driver role : Sage tests Tech. Development board (MCP300) hd7279 keyboard chip whether normal procedures functions : pressing keys on the 1st show 0,1,2,3? Press on the 2nd c, d, e , f, press the button on the 3rd show 4,5, 6,7 press the button shows on the 4th 8,9, a, b, press the button to light up the No. 0 4 LED lights)