说明：  按照音符来设定频率和8253定时/计数器的延时时间。8253的CLK0接1MHz时钟，GATE0接＋5V，OUT0接8255的PA0,J1接喇叭，编程使计算机的数字键1、2、3、4、5、6、7作为电子琴按键，按下即发出相应的音阶。 要求： (1)层以8255接八个开关K1~K8，做电子琴按键输入。 (2) 以8253控制扬声器，拨动不同的开关，发出相应的音阶。
(In accordance with the note to set the frequency and 8253 timer/counter of delay time. 8253 s CLK0 then 1MHz clock, GATE0 then 5 V, OUT0 then 8255 the PA0, J1 next speaker, programming the computer as the number keys 1,2,3,4,5,6,7 flower button, press that issued the corresponding scale. Requirements: (1) layer to 8255 next eight switch K1 ~ K8, so flower keystrokes. (2) 8253 control speakers, struck a different switch, the issue of the appropriate scale.)