The MIT Technology Review has a look back at instant messaging in its regular Trailing Edge feature this month. The technology dates back to the 1980s, when MIT implemented a system that was designed to send notifications about things like server outages to workstation users. Naturally, students discovered that using the system to chat was a lot more fun.
There were other forms of IM in the mainframe world before that. I spent two summers as an intern at USAA in the life actuarial department. My second year there, 1988, my buddy David worked over in Products and Casualty. We both spent some time on the company mainframe, which had the capability of sending a message to another logged on user that would display on the screen the next time the screen changed. (Later on, in the early 90s when I started working at the large multinational firm where I am today, their VM system had the same sort of capability.) We regularly amused ourselves with this feature.
Of course, as is often the case, any piece of technology can be misused. My boss, who was fairly indulgent about my chat habit, told me a story one day about another employee. Seemed this guy had the hots for a babe who worked a few cube rows away. One day he got it in his head to use the mainframe message system to confess his feelings and ask her out on a date. (I can already hear the women in my audience cringing.) Unfortunately, when he sent the message he accidentally used the feature that sends messages to all logged on users. Oops! They chose not to fire him, which in the grand scheme of things may not have been such a blessing. Alas, my boss didn’t know if he at least got a Yes answer from his inamorata.