1．采用位触发方式编写程序，使计算机发出音响并奏出《两只老虎》的乐曲。

通过查阅相关资料，进一步理解程序直接控制I/O方式和位触发方式控制声音的工作原理。

一首乐曲是由不同频率和节拍的音调组成，因此控制脉冲的频率和持续时间是编写乐曲程序的关键。根据已知的音符频率对照表，给出乐曲的频率表；设二分音符持续时间为0.5秒（50*10ms），50作为2拍的计数值，给出乐曲的节拍时间表；

编写程序并调试通过。

2．进一步学习利用定时器产生声音的方法，使计算机奏出乐曲（例如《两只老虎》等）。-1. Way to trigger the use of digital programming, so that the issue of audio computer and play "two tigers" of the music.

Through access to relevant information, a better understanding of procedures for the direct control of I/O mode and digital control to trigger the sound works.

Music is a different tone frequency and the beat of the pulse to control the frequency and duration of the procedure is the key to the preparation of music. Notes the basis of known frequency table, given the frequency of musical scales　based minim duration of 0.5 seconds (50* 10ms), 50 as a value of 2 shot, given the timetable beat music　

Programming and debug through.

2. Further study the use of sound methods have a timer so that the computer to play music (such as "two tigers", etc.).