Xbox 360 Hardrive/dashboard question?

ok so i had the xbox 360 core with no hard drive, memory unit and i had the old dash board so my friend brought over his hard drive and put it on my xbox and then the hard drive had the updated dashboard so now i have the updated dashboard but when he disconnected his hard drive the dashboard was still there and i have no hardrive/memory unit but the new dashboard still stayed on my xbox is it possable that the xbox 360 has a built in hard drive?