I am trying to prototype a system for work that will entail multiple units with a push button, a few leds, and a lcd display that turn on when certain conditions are met. These need to all be controlled from one computer (or maybe the computer controlls one master unit and all the slaves connect to it). I am just looking for an idea of what I need to research to have a computer be able to address at least 100 different units. I keep thinking of something similar to an IP address, but basically I'm at a loss on that part. I don't even know what to google to find my answer. I have a handful of units built and functioning one at a time... now I just need to understand this last part. Any insight that one could provide would be more then appreciated.

Thank you!

For short distance connections look up TWI or I2C which can do 128 adresses I think.