江湖救急

DATA SEGMENT
TAB DB ‘1 2 3 4 5 6 7 8 9 10 11 12‘，0DH, 0AH, ’$’
DATA ENDS
STACK SEGMENT STACK
STA DW 50 DUP(?)
STACK ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK
START: MOV AX,DATA
MOV DS,AX
MOV AX,STACK
MOV SS,AX
MOV DX,21BH
MOV AL,8BH
OUT DX,AL
MOV DX,219H
IN AL,DX
MOV BH,AL
MOV DX,21AH
IN AL,DX
MOV BL,AL
MOV DX,OFFSET TAB
MOV AH,09H
INT 21H
MOV CL,04H
SHR BH,CL
AA: MOV DL,BH
CALL DISP
SHR BH,1
DEC CL
JNZ AA
MOV CX,0008H
BB: MOV DL,BL
CALL DISP
SHR BL,1
LOOP BB
MOV AX,4C00H
INT 21H
DISP PROC NEAR
PUSH AX
AND DL,01H
ADD DL,30H
MOV AH,02H
INT 21H
MOV DL,20H
INT 21H
POP AX
RET
DISP ENDP
CODE ENGS
END START
问题： 用几个端口， 端口地址，工作模式，程序功能，对应关系。

高人指点一下!

楼主就贴出一段代码，信息太少了。