As you know by now, I/O is not directly connected to the CPU, so the RCP's third module - which I haven't mentioned until now - serves as an I/O interface. This block handles communication with the CPU, controllers, game cartridge, and audio/video DACs.
Accessories
In addition to its unorthodox shape, the Nintendo 64 controller includes a connector for plugging in accessories. Notable commercial examples include:
- The Controller Pak: A storage medium, similar to Sony's Memory Card, used to store save game data and share it across consoles.
- The Rumble Pak: Contains a small motor that provides haptic feedback, useful for 'immersing' the player in supported games.
- The Transfer Pak: Provides a slot to connect a Game Boy or Game Boy Color cartridge (Game Pak). This enabled the possibility to run Game Boy games with the help of an emulator, and/or transfer its content.
The Controller Pak .
The Rumble Pak .
The Transfer Pak .
All accessories connected to the controller are managed by the PIF-NUS, an obscure block that also handles security. The RCP communicates with the PIF using a serial bus .