I just got a Raspberry Pi and can run my Teletype off it using its built-in serial port and an external serial to current loop converter. The Pi can also use USB to serial converters and I could add a powered USB hub to run ten terminals or more off it. Can you imagine ten terminals run by a $30.00 device? The TTY will be the limiting factor as far as speed goes. The only problem is that most USB-serial adapters are based on an FTDI chip that has a lower limit of 300 baud. The Teletype runs at a fixed 110 baud. Does anyone know of a USB-serial adapter that works at 110 baud?
I've successfully run three terminals on the Pi (one TTY, one ADM5 at 9600 baud and a 300 baud terminal emulator on a PC) and it's quite a sight. If I could run multiple TTYs, I could recreate a minicomputer room of the 60's and 70's with just a Pi! Woo hoo!