I was an early adopter of the TiVo. You can hook up a terminal to those things. A dumb terminal or terminal software on your computer using your own serial port. There was a terminal/serial port in the back (baud 2600)that took the form of a 3/4" audio plug.

It was a Linux system, but all their own software running on it was written in TCL.

I don't think they were using TK though.

Pretty fun to hack around with. Since it was connected to the phone line, when a call came in it could get the caller ID off the line and display it on the TV screen.