解道题{求助}

[CODE]DATA SEGMENT
BUF DB 5,?
sum1 db ?
sum2 db ?
sum3 db ?
sum4 db ?
ORG 10H
BUF1 DB ?,?,?,'$'
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA
START:
MOV AX,DATA
MOV DS,AX
MOV DX,OFFSET BUF
MOV AH,0AH
INT 21H
mov dl,13
mov ah,2
int 21h
mov dl,10
mov ah,2
int 21h
MOV Al,sum2
SUB Al,30H
mov ah,sum4
sub ah,30h
ADD AL,AH
DAA
MOV BL,AL
AND AL,0FH
ADD AL,30H
MOV SI,OFFSET BUF1
MOV [SI+2],AL
AND BL,0F0H
MOV CL,4
SAR BL,CL
mov al,sum1
sub al,30h
mov ah,sum3
sub ah,30h
add al,bl
add al,ah
daa
MOV BL,AL
AND AL,0FH
ADD AL,30H
MOV [SI+1],AL
AND BL,0F0H
MOV CL,4
SAR BL,CL
ADD BL,30H
MOV [SI],BL
MOV DX,OFFSET BUF1
MOV AH,9
INT 21H
MOV AH,4CH
INT 21H
CODE ENDS
END START[/CODE]

[此贴子已经被作者于2007-7-11 9:29:30编辑过]