When Nintendo launched the N64, they made a few really interesting decisions: it was the last cartridge-based console, it had four controller ports, and it re-introduced the analogue stick to the world. The Nintendo 64's power made better-than-rudimentary 3D games possible, and along with this new dimension came a need for a different controller. Anyone who has played Mario 64 knows beyond the shadow of a doubt that digital controls simply would not suffice. Imagine trying to walk a tightrope when you could only run in 8 directions, and had no speed control beyond stopped and full speed ahead!
So something new was needed, but it wouldn't be easy. Significant challenges were faced when Nintendo designed the new controller, and the placement of nearly every feature was a reasoned response to necessity. Nintendo's engineers must have been insane with the demands placed on them by the N64 software designers, you can just imagine them making more and more demands while the hardware guys overcame one obstacle after another. The mother of all invention pushed Nintendo in several innovative new directions.
Nintendo seems to have started with a SNES-like foundation, with a d-pad on the left, A+B buttons on the right, and two shoulder buttons. But then they got a little weird.
The first challenge was the fitment of both a 2D d-pad and 3D stick, and Nintendo's solution was a wild one: a striking, three-pronged design. A player's right hand was always on the right prong, but the left was free to hold either the left (for 2D) or centre (for 3D) prong depending on the game's requirements. Since the player could no longer reach the left trigger while holding the centre prong, a trigger button was added underneath the centre of the pad.
Sometimes, when blazing new ground, you make a decision that turns out to be less than ideal. Nintendo realized they would need a way to control the camera in 3D games, so they created the C-button: a group of four yellow buttons. They allowed the player to move the camera up, down left and right, and to Nintendo's credit, it worked. It also allowed Nintendo to justify six face buttons, a feature only matched by Sega's Saturn and - somewhat abortively - Microsoft's Xbox. Sony and Microsoft followed Nintendo's lead, but used a second analogue stick instead of the C-buttons. Knowing a good thing when they saw it, Nintendo abandoned the C-button after the N64, using a second analogue stick for their GameCube too.
Nintendo's final innovation was a large slot underneath the front of the pad. Each player could use their own memory card, vibrating rumble-pak or other device during play.
Nintendo also applied the multi-colour option that brought them success during the GameBoy era: N64 controllers were released in a multitude of colours. Mario Kart had a black and white one (shown above), contest winners received gold ones, translucent consoles had matching translucent pads, and a changing variety of colours were sold throughout the system's life. Nintendo once announced a feature that allowed games to detect the pad's colour, changing the player colour to match, but this was rarely (if ever) used.
The N64 pad was, for the most part, exactly what players needed: a comfortable, functional 2D and 3D pad. It made a lot of compromises, but none that significantly detracted from the controller's worth.
Some people found it too large, a side effect of the three-prong design. Even the d-pad was a little larger than the one found on the SNES pad.
The analogue stick used an 8-way gate, just like Nintendo's later GameCube and Wii Classic Pad. As long as the pad was relatively new, it was a joy to play with and use.
All six face buttons were within reach, but the arrangement of the two different sized buttons felt strange as a six-button pad. Nintendo mitigated this somewhat by making the A and B buttons the primary buttons for all games, but it was still odd for 2D games, especially when all four yellow buttons were called C.
Quality-wise the controller was a mixed bag: the analogue stick tended to wear out quickly, but the whole pad was kind of creaky. This was no doubt another side effect of the three pronged design, which offered enthusiastic players a lot of leverage. It was perhaps the least robust of an Nintendo controller: most players who bashed their controllers found they'd break off internal bits, and many used controllers have an annoying rattle.
Considering the demands placed on this controller, it fared remarkably well, and many of the features it introduced, re-introduced or improved on found their way into future pads from all manufacturers.
The analogue stick was very poorly implemented. While the encoding mechanism (a miniature pair of geared optical wheels attached to the stick and read like a trackball or mouse) was clever and functional, the stick itself was plastic, against a plastic fulcrum. It only took a moderate amount of use to wear the fulcrum down so that the stick became increasingly sloppy, with a growing 'dead zone'. After a few months of play most sticks could no long reach the left and right maximums, and players had to replace the entire pad.
Most third party pads used more traditional potentiometer-based analogue sticks, with metal components, offering more reliability than the Nintendo device.
N64 pads used only three wires to communicate with the console.
Panasonic's unreleased 3DO M2 console used 3-prong controller mockup that was a shocking ripoff of the N64 pad.
Nintendo's Mario Party games required players to wiggle the analogue pad in quick circles, and many players injured their hands trying to go ever faster. Nintendo ended up offering free gloves to any player injured in this fashion after several parents complained.