int21-test.asm

为ascii码转换程序

DATA SEGMENT
count   DB 14H
ASC DB ?
DATA  ENDS

code segment                              ;CODE SEGMENT
     assume cs:code,ds:data               ;ASSUEM CS:CODE,DS:DATA
START:
MOV AX,DATA
      MOV DS,AX
mov bl,2
CHA:
      MOV AL,count
      AND AL,0FH           ;高4位清零
      CMP AL,9H                            ;这儿就好加上一个H
      JA  LAB1             ;大于则转移
      ADD AL,30H           ;小于或等于加30h
      JMP LAB2
LAB1:ADD AL,37H            ;大于加37h
LAB2:MOV ASC,AL          ;将结果保存
     
MOV AH,02H
    MOV dl,al
    INT 21H
;
MOV DL,count
MOV  CL,4
SHR DX,CL
MOV count,DL

DEC bl
Jnz CHA
;
MOV AH,4CH
     INT 21H
CODE ENDS
     END START