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一、立即寻址例如:MOVAX,1234H;十六进制数1234H送入AX。错误指令:MOVDS,1234H正确指令:MOVAX,1234HMOVDS,AX错误指令:MOVAH,300正确指令:MOVAX,300二、寄存器寻址例如:MOVAX,BX错误指令:MOVAX,DL正确指令:MOVAH,DL或MOVAL,DL2.两个操作数不能同时为段寄存器错误指令:MOVDS,SS正确指令:MOVAX,SSMOVDS,AX错误指令:MOVCS,AX三、直接寻址MOVAL,[2000H]例:MOVAX,1234HMOV[1000H],AX1234H占据有效地址1000H和1001H两个内存单元MOVAX,1234HMOV[1000H],AX若指令执行前,有DS=2000H,则指令执行后,内存单元:(21000H)=?(21001H)=?34H12H四、寄存器间接寻址例如:MOVAX,[BX];若DS=4000H,BX=100H,40100H单元的内容传至AL寄存器40101H单元的内容传至AH寄存器五、基址寻址寄存器BX或BP例如:MOVAL,[BX+5]如果使用BP,默认段寄存器为SS。六变址寻址例:MOVBX,[SI+100]七、基址变址寻址方式MOVAX,[BX][SI]MOVAX,[BP][DI+100]MOVBL,[BX+DI+200]4.设DS=2000H,SS=2100H,SI=00A0H,BX=0100H,BP=0010H,试指出下列各指令中源操作数的寻址方式是什么?其物理地址是什么?(1)MOVAX,2345H立即寻址已知:DS=2000H,SS=2100H,SI=00A0H,BX=0100H,BP=0010H,(20100H)=12H,(20101H)=34H(2)MOVAX,BX寄存器寻址(3)MOVAX,[100H]直接寻址物理地址:20100H指令执行后,AX=3412H已知:DS=2000H,SS=2100H,SI=00A0H,BX=0100H,BP=0010H,(20100H)=12H,(20101H)=34H(4)MOVAX,[BX]寄存器间接寻址指令执行后,AX=3412H已知:DS=2000H,SS=2100H,SI=00A0H,BX=0100H,BP=0010H,(21010H)=34H,(21011H)=56H(5)MOVAX,[BP]寄存器间接寻址指令执行后,AX=5634H已知:DS=2000H,SS=2100H,SI=00A0H,BX=0100H,BP=0010H,(21100H)=54H,(21101H)=11H(6)MOVAX,[BX][1000H]基址寻址指令执行后,AX=1154H已知:DS=2000H,SS=2100H,SI=00A0H,BX=0100H,BP=0010H,(21100H)=54H,(21101H)=11H(7)MOVAX,[SI][1000H]变址寻址(8)MOVAX,[BP][SI]基址变址寻址
本文标题:寻址方式
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