用汇编语言编写一个运算器的程序

.model
.stack
.code
a dw ?
b dw ?
c dw ?
d dw ?
e dw ?
f dw ?
g db ' computer $'
esc_key equ 1bh
win_ulc equ 30
win_ulr equ 7
win_lrc equ 50
win_lrr equ 16
win_width equ 20
display equ 2h
key_in equ 1h
doscall equ 21h
mul1 db ?
mul2 db ?
main proc far
call clear_screen
mov dx,0

mov ah,2
mov dh,7
mov dl,29
mov bh,0
int 10h
mov ah,9
mov al,'$'
mov bh,0
mov bl,0dah
mov cx,21
int 10h

mov ah,2
mov dh,7
mov dl,30
mov bh,0
int 10h
mov cx,20
loop1:
; mov dl,'_'
; mov ah,2
; int 21h
; loop loop1
locate1:
mov dx,0
mov ax,0
mov bx,0
mov cx,0
mov a,0
mov b,0
mov c,0
mov d,0
mov e,0
mov dh,7
mov cx,10
loop4:
mov