汇编语言编程求1*2*3*4*5*6*7，将结果存入fac中并显示出来

assume cs:code
data segment
    fac dw 1
data ends

code segment
start:
    mov ax, 1
    mov bx, 2
    mov cx, 7
    mov dx, 0
    mov si, offset fac
    mov [si], ax
    mov [si+2], dx
L1:
    mul bx
    mov si, offset fac
    mov [si], ax
    mov [si+2], dx
    inc bx
    loop L1
    mov ah, 09h
    lea dx, [fac]
    int 21h
    mov ah, 4ch
    int 21h
code ends
end start