The thin-film head was developed by the magnetic recording research group, but the magnetic bubble group next door hijacked a copy, and that's where it saw the first light of day -- as seen in this 1970 film clip, which shows a magnetic bubble making three trips around a circular shift register. The sensor sits next to the bubble path in the lower right, and its signal is shown in the oscilloscope trace to the right. Click here for more details. (Turn the sound on. Yes, we really did rig a bell for a few of our demos).