解释一个汇编程序

code segment
assume cs:code
main proc far
start:
push dx
mov ax,0
push ax
mov bx,0

mov ah,1
int 21h
mov bl,al
mov ah,2
mov dl,13
int 21h
mov ah,2
mov dl,10
int 21h

mov ah,1
int 21h
mov bh,al
mov ah,2
mov dl,10
int 21h
mov ah,2
mov dl,13
int 21h

sub bh,30h
sub bl,30h
mov al,bh
mul bl

mov bx,ax
call binidec
ret
main endp

binidec proc near
mov cx,10
call dec_div
mov cx,1
call dec_div
ret
dec_div proc near
mov ax,bx
mov dx,0
div cx
mov bx,dx
mov dl,al
add dl,30h
mov ah,2
int 21h
ret
dec_div endp
binidec endp
code ends
end start

这是一段就算两个一位数乘法的程序，谁能帮忙做一下解释，详细一点的，多谢拉。