1 编写程序,从键盘接收一个小写字母,然后找出它的前导字符和后续字符,再按顺序用大写字母显示这三个字符
【解】:MAIN PROC FAR start: push ds sub ax,ax push ax input: mov ah,7H int 21H cmpe: cmp al,20H JE exit cmp al,61H JL input cmp al,7AH JG input print: sub al,01H mov dl,al mov ah,02H int 21H add al,01H mov dl,al mov ah,02H int 21H add al,01H mov dl,al mov ah,02H int 21H ;输出换行回车 mov dl,0AH mov ah,02H int 21H jmp input exit : ret MAIN ENDP END start 5
2 将AX 寄存器中的16 位数分成4 组,每组4 位,然后把这4 组数分别放在AL、BL、CL 和DL 中
【解】:DB 4 dup(
stack 100H
code MAIN PROC FAR start: push ds and ax,00H push ax mov ax,1234H mov cx,04H mov si,00H lop: push cx mov cl,04H rol ax,cl push ax and al,0FH mov BYTE PTR x[si],al pop ax pop cx add si,2 Loop lop mov al,[X] mov bl,[X+2] mov cl,[X+4] mov dl,[X+6] print: mov ah,02H int 21H mov dl,al mov ah,02H int 21H mov dl,bl m