RMS told a story about the introduction of a new printer at the AI lab. The gist was that the manufacturer of the new printer would not release the source code

RMS told a story about the introduction of a new printer at the AI lab. The gist was that the manufacturer of the new printer would not release the source code (which was also under claimed copyright). At the time, this was a novelty; code was released so that people could modify it to work with the rest of the hardware they happen to have. The way RMS wrote of the event, I had the impression he felt shocked and betrayed. That was the inciting incident.