Someone at school asked me if you could chat using TI calculators. I said yes (but I want to make money) so I didn't give them any info on how. That led me into this project. I want to create a network of 84s and 82s, using a wireless version of Token Ring for layer 2 communications. I plan to make the wireless encoder/decoder myself, and make a few z80 MAU's for it.

I have 2 questions

1) What would be an extremely lightweight layer 3 protocol I could use
2) What is a good frequency to use

How wide is the beam, and how wide is the sensor's angle of sensitivity? Can you have more than two in the conversation? With three, someone's angles will be no less than 30° off axis. With 4, it becomes at least 45° off axis.

I'm not familiar with the TI-84 and relatives; but you may not really need much of a protocol at all if you can send text from the keyboard when you press <Return> (or other key) to send the text you just typed, and if it can put received text in a little window. If the transmission speed is a lot higher than your typing speed, the chances of a collision, ie, that two people would be sending at once, is very slim, and not a big problem if these calculator users are hardly out of arm's reach of each other. Beyond that, each one would just send an identifier name at the beginning of each transmission like "James says:". You're not looking for any secrecy are you (like cell phones near each other can carry on separate private conversations)?