jmp 07c00h ; boot code start; off we go, unconditionally
mov ah, 09h; execution will not reach here unless there's a branch to here
mov al, 97; from somewhere else.
mov bx, 100b
mov cx, 01h
int 10h
times 0x1fe-$ db 00h ; pads with 0's
db 55h,0aah ; boot signature
This is pretty sparse, information wise. Issues such as privilege may or may not arise.