The 486 that [someyob] is restoring had the Turbo button, but sadly there was just a simple LED to show whether or not it was engaged.

But if you can push your button while your yellow LED is lit, the light speeds up tremendously until the next button press in the green. Our only wish is that subsequent yellow-light button ...

Learn how to connect multiple buttons to just one Arduino pin using clever wiring and resistor techniques. Perfect for compact projects, keyboards, or when using small boards like the Nano or Pro ...