按零基础汇编上编写的，nasm编译，vmware11虚拟机运行，不能输出字符串，请高手指点！！
org 07c00h

mov ax,cs
mov es,ax
mov bp,msgstr

mov cx,12
mov dh,12
mov dl,36
mov bh,0
mov al,1
mov bl,0ch
mov ah,13h
msgstr: db "hello my os!"
int 10h
times 510-($-$$) db 0
dw 55aah
jmp $