八.利用定时器产生乐曲\main.c .....................\main.LST .....................\main.OBJ .....................\mucis .....................\mucis.hex .....................\mucis.M51 .....................\mucis.Opt .....................\mucis.plg .....................\mucis.Uv2 .....................\STARTUP.A51 .....................\STARTUP.lst .....................\STARTUP.obj 八.利用定时器产生乐曲