指令系统学习.docVIP

1.求从0开始连续100个偶数之和，并将结果存入名字为SUM的字存储单元中。试用完整的段定义语句编写出实现这一功能的汇编源程序。 答：程序如下： DATA? SEGMENT ? ? SUM?? DW? 0 DATA? ENDS STACK SEGMENT STACK ????? DB? 200 DUP(0) STACK ENDS CODE? SEGMENT ????? ASSUME? DS:DATA, SS:STACK, CS:CODE START:MOV AX, DATA ????? MOV DS, AX ????? MOV CX, 100 ????? MOV AX, 0 ????? MOV BX, 0 NEXT: ADD AX, BX ????? INC BX ????? INC BX ????? DEC CX ????? JNE NEXT ????? MOV SUM, AX ????? MOV AH, 4CH ????? INT 21H CODE? ENDS ????? END START 2.设一存储区中存放有10个带符号的单字节数，现要求分别求出其绝对值后存放到原单元中，试编写出汇编程序。 答：程序如下： ??? ????DATA??? SEGMENT BLOCK ??DB -10,15H,20H,-1,-23,46H,16H,-33,65H,88H ? DATA??? ENDS ? CODE??? SEGMENT ????????? ASSUME DS:DATA, CS:CODE ? START:? MOV??? AX, DATA ????????? MOV??? DS, AX ????????? MOV??? SI, OFFSET? BLOCK ????????? MOV??? CX, 10 ? AGAIN:? MOV??? AL, [SI] ????????? TEST?? AL, 80H???? ;测试是否为正数 ????????? JZ ??? NEXT ????????? NEG??? AL????????? ;求负数的绝对值 ????????? MOV??? [SI], AL ? NEXT:?? INC??? SI ????????? LOOP?? AGAIN ????????? MOV??? AH, 4CH???? ;返回DOS ????????? INT??? 21H ? CODE??? ENDS ????????? END??? START 3.假定DX和BX中各包含有4位压缩BCD数（1234和5678），将DX和BX中的BCD数相加且将和数存入CX，试编写出实现这一功能的汇编源程序。 答：程序如下： ??CODE? SEGMENT ??????????? ?ASSUME CS:CODE ?????? START:MOV DX, 1234H? ????;装入1234 ????? ?MOV BX, 5678H? ????;装入5678 ????? ?MOV AL, BL???? ????;低字节之和 ????? ?ADD AL, DL ????? ?DAA??????????????? ;低字节调整 ????? ?MOV CL, AL???? ????;和数低字节送CL ????? ?MOV AL, BH???? ????;高字节及进位之和 ????? ?ADC AL, DH ????? ?DAA??????????????? ;高字节调整 ????? ?MOV CH, AL ????????;和数高字节送CH ????? ?MOV AH, 4CH ????? ?INT 21H CODE?? ENDS ????? ?END??? START 4.在当前数据段、偏移地址为DATA的内存区中，顺序地存放着以BLOCK为首址的8个字节的无符号数，若要求其算术平均值，并将结果接着这8个数存放，试编写此汇编程序。? 答：程序如下： DATA ???SEGMENT ??? BLOCK?? DB? 1,2,3,4,5,6,7,12 ??? P_SUM?? DB? ? ??? DATA??? ENDS ??? CODE??? SEGMENT ??????????? ASSUME? CS:CODE, DS:DATA ??? START:? MOV AX, DATA ??????????? MOV DS, AX ??????????? MOV CX, 8?????? ???? ;置循环计数器 ??????????? LEA DI, BLOCK?? ???? ;取数据块首址 ??????????? MOV AX, 0?????? ???? ;AX用于数组求和 ??????????? MOV AL, [DI]???