The Nintendo Four Score was a controller attachment for the original Nintendo Entertainment System which allowed you to use four controllers at one time. [Simon Inns] wanted to use some original NES controllers on his computer so he developed a drop-in replacement board that converts the device to USB.
As we’ve seen with other NES controller hacks, the hardware uses a simple parallel to serial shift register to deliver key-presses to the console. This means that reading four controllers at a time is no different than shifting in data to a microcontroller from the four different sources. The remaining portion of the problem is providing a USB connection that enumerates the device as a joystick. We’ve seen a bunch of USB projects from [Simon] so it’s no surprise that he was able to pull it off.
He went with the ATmega16U2 which has built-in support for USB. [Simon] wrote the code so that although there is only one USB cable, each of the four controller ports will appear as a separate USB joystick on the computer. To button up the project he carefully measured the original board and laid out his own version so that it fits the footprint of all the original components as well as the mounting brackets on the case. Top notch [Simon]!