Here is a true story about a glass tty: One day an MIT hacker was in a motorcycle accident and broke his leg. He had to stay in the hospital quite a while, and got restless because he couldn't hack. Two of his friends therefore took a terminal and a modem for it to the hospital, so that he could use the computer by telephone from his hospital bed.
Now this happened some years before the spread of home computers, and computer terminals were not a familiar sight to the average person. When the two friends got to the hospital, a guard stopped them and asked what they were carrying. They explained that they wanted to take a computer terminal to their friend who was a patient.
The guard got out his list of things that patients were permitted to have in their rooms: TV, radio, electric razor, typewriter, tape player, ... no computer terminals. Computer terminals weren't on the list, so the guard wouldn't let it in. Rules are rules, you know. (This guard was clearly a droid.)
Fair enough, said the two friends, and they left again. They were frustrated, of course, because they knew that the terminal was as harmless as a TV or anything else on the list... which gave them an idea.
The next day they returned, and the same thing happened: a guard stopped them and asked what they were carrying. They said: "This is a TV typewriter!" The guard was skeptical, so they plugged it in and demonstrated it. "See? You just type on the keyboard and what you type shows up on the TV screen." Now the guard didn't stop to think about how utterly useless a typewriter would be that didn't produce any paper copies of what you typed; but this was clearly a TV typewriter, no doubt about it. So he checked his list: "A TV is all right, a typewriter is all right ... okay, take it on in!"
[Historical note: Many years ago, "Popular Electronics" published solder-it-yourself plans for a TV typewriter. Despite the essential uselessness of the device, it was an enormously popular project. Steve Ciarcia, the man behind "Byte" magazine's "Circuit Cellar" feature, resurrected this ghost in one of his books of the early 1980s. He ascribed its popularity (no doubt correctly) to the feeling of power the builder could achieve by being able to decide himself what would be shown on the TV. --ESR]
[Antihistorical note: On September 23rd, 1992, the L.A. Times ran the following bit in Steve Harvey's `Only in L.A.' column:
It must have been borrowed from a museum: Solomon Waters of Altadena, a 6-year-old first-grader, came home from his first day of school and excitedly told his mother how he had written on "a machine that looks like a computer-but without the TV screen."
She asked him if it could have been a "typewriter."
"Yeah! Yeah!" he said. "That's what it was called."
I have since investigated this matter and determined that many of today's teenagers have never seen a slide rule, either.... - ESR]