The NES controller is a deceptively simple device — just 8 buttons, serialized through a shift register mapped to memory.
In Nyxx, controller input is now wired up through memory-mapped I/O at $4016, faithfully emulating the read and strobe behavior.
Writing to $4016 resets the shift register; reading from it advances and returns button states in sequence. This implementation enables real-time input, button polling, and eventually, gameplay.
It's a small piece of hardware, but it’s how the player speaks to the machine — and in Nyxx, that channel is now open.
| Keyboard Key | NES Button | Note |
|---|---|---|
| Z | A | Primary action / jump |
| X | B | Secondary action / run / fire |
| Space | Select | Menu toggle / player switch |
| Enter | Start | Game start / pause |
| ↑ | Up | D-pad up |
| ↓ | Down | D-pad down |
| ← | Left | D-pad left |
| → | Right | D-pad right |
| Esc | — | Quit emulator (debug shortcut) |
By connecting to Nyxx, you’re not just pressing buttons — you’re reaching across time, into the circuitry of a machine that sparked imaginations half a century ago.
In your hands, the past runs again — cycle by cycle, opcode by opcode.