Any competent PLATO programmer can quickly hack together a simple chat program that lets two users exchange typed one-line messages. PLATO’s architecture makes this trivial. A few such programs existed on PLATO before 1973, but they did not get much use, probably because the user community was quite small and most terminals were still in a single building.
In the fall of 1973, Doug Brown designed a program that let several users chat as a group. He wrote a simple prototype to demonstrate the concept and called it Talkomatic.
The real magic of Talkomatic was that it transmitted characters instantly as they were typed, instead of waiting for a complete line of text. The screen was divided into several horizontal windows, with one participant in each. This let all the participants type at once without their messages becoming a confusing jumble. Seeing messages appear literally as they were typed made the conversation feel much more alive than in line-by-line chat programs.
I worked with Doug to expand Talkomatic to support multiple channels and add other features. Each channel supported up to five active participants and any number of monitors, who could watch but couldn’t type anything. (One drawback to the Talkomatic approach is that the size of the screen limits the number of participants in a channel.)
Empty channels were open to anyone, but any active participant in a channel could choose to “protect” it. This prevented anyone from monitoring the channel, and the participants could then decide who else to admit.
Talkomatic was an instant hit. Soon it was logging over 40 hours of use per day. It was not officially part of the PLATO system software, and in fact it was used mostly for what administrators would consider frivolous purposes. There was no way to contact a specific person to let them know you wanted to talk, so it was more like a virtual water cooler than a telephone substitute. People would hang out in a channel and chat or flirt with whoever dropped by.
But Talkomatic was so appealing that it inspired the system staff to create an officially supported chat feature. It became known as “term-talk” because it could be accessed from anywhere on PLATO by pressing the TERM key and typing “talk”. The TERM key was originally meant to provide hypertext-like branching to term definitions. In practice, it was rarely used for terms, but it was handy for instant access to features like “talk”.
A “term-talk” conversation was limited to two people, but had its own advantages: you could page a specific person, and you could use it without exiting from whatever else you are doing. A person receiving a page would see a flashing message at the bottom of the screen identifying the pager, and could use “term-talk” to accept. The bottom two lines of the screen then became a miniature Talkomatic. An unwanted page could be rejected with “term-busy”, or simply ignored until the pager gave up.
A feature was later added to “term-talk” that allowed the participants to switch to “monitor” mode, in which one person could actually view the other’s screen. The person being monitored was free to move about the system normally, editing files, running programs, etc. This was extremely useful for remote consulting: someone who needed help could literally show an online consultant what they were trying to do while maintaining a conversation at the bottom of the screen. To ensure privacy, monitor mode could be initiated only by the person whose screen was to be monitored.
Update, April 2014: Talkomatic has now been re-created on the web.