这道题怎么做？

<p>系统中接入一片中断控制器芯片8259A，用来实现CPU与外部设备的数据通讯，系统为8259A的8个中断源在中断矢量表中分配的地址范围为如下图所示，由IR5产生一个上升沿触发外部中断，设置中断屏蔽字屏蔽除IR5以外的其他7个中断源，8259A与CPU连接的方式为非缓冲方式，中断结束方式采用非自动结束方式，中断优先级为一般全嵌套，系统给8259A分配的两个端口地址为20H和21H，请设计8259A的初始化程序。（30分）</p><table><tbody><tr style="vertical-align: top;" ><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>中断源</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR0</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR1</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR2</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR3</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR4</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR5</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR6</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>IR7</p></td></tr><tr style="vertical-align: top;" ><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>中断矢量表中的地址</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>30H</p><p>I</p><p>33H</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>34H</p><p>I</p><p>37H</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>38H</p><p>I</p><p>3BH</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>3CH</p><p>I</p><p>3FH</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>40H</p><p>I</p><p>43H</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>44H</p><p>I</p><p>47H</p></td><td class="s7" style="word-wrap: break-word; vertical-align: middle;" ><p>48H</p><p>I</p><p>4BH</p></td></tr></tbody></table><p><br ></p>