[1][2][non-primary source needed] It replaced the Robotics Invention System, the first-generation Lego Mindstorms kit.
A second-generation set, Lego Mindstorms NXT 2.0, was released on August 1, 2009, with a color sensor and other upgrades.
The kit's main component is the NXT Intelligent Brick computer, which can accept input from up to four sensors and control up to three motors with a modified version of RJ12 cables (similar to, but incompatible with, RJ11 phone lines).
[6] Lego has released open source firmware for the NXT Intelligent Brick and schematics for all hardware components.
The kit's retail version includes software for writing programs that run on Windows and Mac OS personal computers.
Sensors are connected to the NXT brick with a six-position modular connector with analog and digital interfaces.