请大家指点：
code segment
start: mov ax,cs
mov ds,ax
mov bx,0
s: mov cl,[bx]
mov ch,0
sub cl,0
jcxz ok
inc bx
loop s
ok: dec cx
mov dx,bx
mov ah,4ch
int 21h
code ends
end start
root@yeah /cygdrive/d/asm
$ debug j93.exe
-r
AX=0000 BX=0000 CX=001A DX=0000 SP=0000 BP=0000 SI=0000 DI=0000
DS=13F9 ES=13F9 SS=1409 CS=1409 IP=0000 NV UP EI PL NZ NA PO NC
1409:0000 8CC8 MOV AX,CS
-t
AX=1409 BX=0000 CX=001A DX=0000 SP=0000 BP=0000 SI=0000 DI=0000
DS=13F9 ES=13F9 SS=1409 CS=1409 IP=0002 NV UP EI PL NZ NA PO NC
1409:0002 8ED8 MOV DS,AX
-t
AX=1409 BX=0000 CX=001A DX=0000 SP=0000 BP=0000 SI=0000 DI=0000
DS=1409 ES=13F9 SS=1409 CS=1409 IP=0004 NV UP EI PL NZ NA PO NC
1409:0004 BB0000 MOV BX,0000
-d ds:0 f
1409:0000 8C C8 8E D8 BB 00 00 8A-0F B5 00 80 E9 00 E3 03 ................
-g 16
AX=1409 BX=0005 CX=FFFF DX=0005 SP=0000 BP=0000 SI=0000 DI=0000
DS=1409 ES=13F9 SS=1409 CS=1409 IP=0016 NV UP EI NG NZ AC PE NC
1409:0016 B44C MOV AH,4C
-t
AX=4C09 BX=0005 CX=FFFF DX=0005 SP=0000 BP=0000 SI=0000 DI=0000
DS=1409 ES=13F9 SS=1409 CS=1409 IP=0018 NV UP EI NG NZ AC PE NC
1409:0018 CD21 INT 21
-r dx
DX 0005
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