填空题1.3162.213H3.2、31、54.端口A和端口C的高4位端口B和端口C的低4位5.3216.22DH7.单工半双工全双工8.数据位校验位9.DTRDSRRTSCTS10.MCRMSR选择题1.B2.C3.C4.D5.C6.C7.B8.B9.D应用简答题片选信号是有地址译码器产生的，用于确定芯片基地址和进行芯片选择的信号。如果芯片内部有5个不同寄存器则需要3根地址线对其内部寄存器进行译码。MOVDX,43HMOVAL,00110110BOUTDX,ALMOVDX,40HMOVAX,2000OUTDX,ALMOVAL,AHOUTDX,AL假设端口基地址为40H，通过计算可以知道需至少用到两个计数器，不妨用计数器0和1，同时分别设定初值为40000和200即可，这样可以完成程序的核心代码如下：MOVAL,00110110BOUT43H,ALMOVAX,40000OUT40H,ALMOVAL,AHOUT40H,ALMOVAL,01010100BOUT43H,ALMOVAX,200OUT41H,AL连线示意简图如下：MOVDX,43HMOVAL,10110000BOUTDX,AL…MOVDX,40HINAL,DX…MOVDX,41HOUTDX,AL不妨用PB输入，PA输出，程序代码如下：IO8255BASEequ200HIO8255AequIO8255BASEIO8255BequIO8255BASE+1IO8255KequIO8255BASE+3DATASEGMENTVARDB00HDATAENDSCODESEGMENTASSUMECS:CODE,DS:DATASTART:MOVDX,IO8255KMOVAL,10000010BOUTDX,ALL:MOVDX,IO8255BINAL,DXMOVVAR,ALMOVDX,IO8255AMOVAL,VARMOVCX,8L1:TESTAL,01HJNZL2SARAL,1LOOPL1ANDAL,00HJMPL3L2:ANDAL,01HROLAL,CLOUTDX,ALJMPL3L3:MOVAH,01HINT16HJZLMOVAH,4CHINT21HCODEENDSENDSTART不妨采用方式0的方式对8253定时信号进行查询，从而保证程序运行，代码如下:IO8255BASEequ200HIO8255AequIO8255BASEIO8255CequIO8255BASE+2IO8255KequIO8255BASE+3IO8253BASEequ40HIO82530equ40HIO82531equ41HIO8253Kequ43HCODESEGMENTASSUMECS:CODE,DS:DATASTART:MOVAL,10001001BMOVDX,IO8255KOUTDX,ALMOVAL,00000001BL1:MOVDX,IO8255AOUTDX,ALROLAL,1CALLDELAYJMPL1DELAYPROCPUSHAXMOVAL,00110110BOUTIO8253K,ALMOVAX,20000OUTIO82530,ALMOVAL,AHOUTIO82530,ALMOVAL,01010100BOUTIO8253K,ALMOVAL,100OUTIO82531,ALL2:MOVDX,IO8255CINAL,DXTESTAL,00000010BJZL2POPAXRETDELAYENDPCODEENDSENDSTART连线简图如下：8255A工作在方式1时，使用的握手信号有两类：输入时，使用数据选通信号，输入缓冲器满信号IBF和中断请求信号INTR。输出时，使用输出缓冲器满EQ，外设应答信号和中断请求信号INTR。每个字符信息长度=1+7+1+1=10bit所以每秒传输字符数=3600/10=360,即每秒发送360个字符空闲启动字符数据奇校验停止101/01/01/01/01/01