寄存器BP初始值为零，为什么还要手动mov bp,0初始化解决方法

assume cs:code,ds:data,es:strack

data segment
    db 'welcome to masm'
data ends

strack segment
    db 0,0,0,0,0,0
strack ends

code segment
    start:
    mov ax,strack
    mov ss,ax
    mov sp,8

    mov ax,data
    mov ds,ax
    mov ax,0B800h
    mov es,ax
    
    mov bp,0            ;就是她，爱她不容易
    mov bx,0
    mov cx,3
    s:
    push cx
    
    mov bx,0
    mov di,0
    mov cx,15
    s1:
    mov al,[bx]
    mov es:[bp][di],al
    inc bx
    add di,2
    loop s1
    
    add bp,160
    pop cx
    loop s
   
    mov bp,0
    mov si,1
    mov al,11110010b
    mov cx,15
    s2:
    mov es:[bp][si],al
    add si,2
    loop s2

    mov bp,160
    mov si,1
    mov al,10100100b
    mov cx,15
    s3:
    mov es:[bp][si],al
    add si,2
    loop s3

            
    mov bp,320
    mov si,1
    mov al,11110001b
    mov cx,15
    s4:
    mov es:[bp][si],al
    add si,2
    loop s4
    
    mov ax,4c00h
    int 21h
code ends

end start