调用显示功能为啥子放在那里，为啥不放在别的地方，不太懂
DSEG SEGMENT
MEM DB 20,0,20 DUP(0)
DSEG ENDS
;
CSEG SEGMENT
ASSUME CS:CSEG,DS:DSEG
START:MOV AX,DSEG
MOV DS,AX
MOV AH,0AH
INT 21H
MOV BL,18
NEXT1:LEA DI,MEM+2
MOV SI,DI
MOV CL,BL
NEXT2:MOV AL,[SI]
ADD SI,1
CMP AL,[SI]
JNC NEXT3
MOV DL,[SI]
MOV [SI-1],DL
MOV [SI],AL
NEXT3:DEC CL
JNZ NEXT2
DEC BL
JNZ NEXT1
XOR CX,CX
MOV CL,MEM+1
MOV DX,OFFSET MEM+2
MOV BX,DX
ADD BX,CX
MOV BYTE PTR[BX],"$"
MOV AH,09H
INT 21H
MOV AH,4CH
INT 21H

CSEG ENDS
END START