1.
答案：
2. 、
答：
4. 省道
(1)
A1、A0：地址选择线,用来选择8255的PA口,PB口,PC口和控制寄存器
| A1 | A0 ||
| --- | --- |--- |
| 0 | 0 | A口 |
| 0 | 1 | B口 |
| 1 | 0 | C口 |
| 1 | 1 | 程序状态寄存器 |
| A9 | A8 | A7 | A6 | A5 | A4 | A3 | A2 | A1 | A0 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | x | x |
答：
5. 地方
6. 得分
