qnli question: What was the name of the convention where Nintendo unveiled its American version of the Famicom? sentence: Some varieties of these launch games contained Famicom chips with an adapter inside the cartridge so they would play on North American consoles, which is why the title screen of Gyromite has the Famicom title "Robot Gyro" and the title screen of Stack-Up has the Famicom title "Robot Block".