On the plus side, the ECS "did" include a built-in BASIC that was somewhat functional, if idiosyncratic and occasionally buggy, and a second AY-3-8910 sound chip which expanded the system's audio capabilities to six-voice synthesized sound and, when paired with the optional 49-key Music Synthesizer keyboard, could potentially turn the Intellivision into a polyphonic synthesizer for playing, recording, or learning music. It would also allow two additional hand-held Game Controllers to be connected in place of the alphanumeric keyboard, which opened up the possibility of four-player games.