A friend of mine had one of these (1998-99): https://electronics.howstuffworks.com/gadgets/home/digital-jewelry3.htm https://electronics.howstuffworks.com/gadg

A friend of mine had one of these (1998-99): https://electronics.howstuffworks.com/gadgets/home/digital-jewelry3.htm https://electronics.howstuffworks.com/gadgets/home/digital-j... > The Java Ring is a stainless-steel ring, 16-millimeters (0.6 inches) in diameter, that houses a 1-million-transistor processor, called an iButton. The ring has 134 KB of RAM, 32 KB of ROM, a real-time clock and a Java virtual machine A wearable device that could run arbitrary portable code was a cool idea.