3．　　计算机钢琴的程序：
编写程序，程序运行时，使PC机成为一架可弹奏的“钢琴”，循环演奏简单的的音乐，，按CTR键返回DOS。
,3. Computer Piano procedure: the preparation of procedures, program runs, so that PC-1 may be playing to become the　piano , a simple cycle of concerts of music, according to CTR button to return to DOS.