1. 用键盘是吸纳钢琴的功能； 2. 要求最少能够实现一个音调的低音、中音和高音部分； 3. 音高的切换用组合键实现 ； 提示： 通过对8253的编程实现发声程序的设计。 -1. To use the keyboard function is to absorb the piano　2. The requirements can be achieved at least a bass tone, in part treble tone　3. Pitch the switch to achieve with a combination of keys　Tip: By 8253 Voice of programming procedures design.