IBM PC/XT 机内发音电路原理及发音电路中各接口芯片的作用。掌握8253定时/记数器芯片和8255并行接口芯片的编程方法。掌握音乐程序的设计、编程方法。-IBM PC/XT machine pronunciation pronunciation of the circuit schematic and the role of the interface chip. 8253 master timer/counter chip and 8255 parallel interface chip programming. Master musical program design, programming methods.