the simplest operating system that only shows the words "Hello,OS!" on screen after computer startup

hello_os.asm

	org 07c00h		; tell the complier put this code to 0x7c00
%endif
	mov ax, cs
	mov ds, ax
	mov es, ax
	call DispStr	; call sub-func
	jmp $			; while(1); $ means current address;
DispStr:
	mov ax, BootMessage
	mov bp, ax
	mov cx, 16
	mov ax, 01301h
	mov bx, 000ch
	mov dl, 0
	int 10h
	ret
BootMessage:	db	"Hello, OS!"
times 510-($-$$) db 0 	; $$ means the beginning of this section
						; in this case is 0x07cc
dw 0xaa55				; end flag; known as boot section