Page "Intellivision" Paragraph 18

Ultimately, this fulfilled the original promises of turning the Intellivision into a computer, making it possible to write programs and store them to tape, and interfacing with a printer well enough to allow Mattel to claim that they had delivered the promised computer upgrade and stop the FTC's mounting fines.

It even offered, via an additional AY-3-8910 sound chip inside the ECS module and an optional 49-key Music Synthesizer keyboard, the possibility of turning the Intellivision into a multi-voice synthesizer which could be used to play or learn music.