Re:There were three until this... (Score 1)

There's one in the National Cryptologic Museum in Fort Meade, MD. Actually they have a few of them, but they have one out in the open so that you can mess with it and encrypt/decrypt stuff. It's quite amusing to play with, but you gotta wonder how long it took to send any message of serious length with it. Think of typing on a REALLY SLOW manual typewriter with a pencil in your other hand writing stuff down. If you're ever in the area check it out.