说明：  编写程序，程序运行时使PC机成为一架可弹奏的“钢琴”。当按下数字键0~9时，发出6，7，1，2，3，4，5，6，7，i，十个音调，按‘.’则退出“钢琴”状态。
(The preparation of procedures, procedures to enable run-time PC-1 may be playing to become the Piano. When pressing the number keys 0 to 9 o clock, issued 6,7,1,2,3,4,5,6,7, i, 10 tones, according to . Then withdraw from the piano state.)