Summary: The Java Ring, a piece of jewelry with 6 kilobytes of RAM, represented an early step towards computers that integrate into our physical environment.
The Java Ring is a tiny wearable computer with 6 kilobytes of RAM. Six K may not sound like much, but it is 20% more memory than the first computer I ever used (back in high school in 1973): an ancient (even at the time) Danish second-generation computer called Gier. The Gier took up an entire room and now I can carry more computer power on my finger.
Even 6 K is enough to hold your secret codes, your credit cards numbers, your driver license, other wallet contents, and even some electronic cash. The ring can also store a few important URLs. Indeed, one of the current JavaRing demos is the ability for me to walk up to any computer in the world that has a JavaRing reader and have my home page loaded simply by touching the ring to the reader (see the photo).
The current Java Ring (from 1998 when this article was written) is admittedly mainly a demo, though it does perform useful tasks such as opening locked doors for authorized personnel. In the future, it will obviously be possible to build rings with much more memory than 6 K, and many more applications will be implemented.
From a user interface perspective, one can also hope that future rings will be designed by jewelry designers and look less nerdy. Also, it would be possible to gain the same functionality in a watch or a belt buckle. The key issue about a wearable computer is not whether it is a ring or another form factor: the deciding point is that you will always have it with you. Many aspects of computing change once there is no need to go to a special room to get at the computer.
(For more on wearable computers, see Tog's proposed iWatch.)