根据乐曲中不同的音符是由输出不同频率的声波而产生的原理，通过设置PC机中 8253定时器不同的计数值，可由扬声器发出不同的曲调。 以下是实现PC机作为一架可弹奏的钢琴演奏预定的曲调。程序中采用了INT 21H软中断调用了DOS的常用子程序。-According to different notes in music from the output generated sound waves of different frequencies principle, PC, in 8253 by setting the timer counts different, different tunes by the speaker. The following is to achieve as a PC, can be scheduled to play the piano tunes. INT 21H process using the DOS software interrupt call common routines.