This is a square-wave oscillator with TURBO modulation effect built into well used Nintendo MAX controller.
The square-wave gives you a classic lofi sound. It’s played with a large knob which controls the frequency. Hitting “A” has the knob work from a high to low pitch and “B” is the reverse. Pressing both merges this into one frequency that causes the knob to play from high to low and back to high which gives you a bit of flexibility.
TURBO works the same as A and B but with a quick pitch modulation.
Where “start” was is now the on/off switch, “select” is not used, and in the upper left corner is a bright red LED light. Power and signal are connected through the original wire to a standard 1/4″ jack (perfect for connecting to amps, effects, or recording equipment). From the jack runs a power cord to a US style wall adapter.
Limited to 2.