How N64 Works

Just as Atari ushered in the dawn of the home video game, Nintendo is largely considered to be the company that revolutionized the industry with the introduction of the Nintendo Entertainment System (NES) in 1985. An 8-bit system based on the 6502 processor and some custom chips, the NES came together with Super Mario Brothers; this inclusion of an accurate home version of one of the most popular arcade games at the time turned out to be pure genius. Sales of the NES were phenomenal. This established Nintendo as the dominant home video game manufacturer until the late '90s, when it was eclipsed by the rival Sony PlayStation.

In 1989, Nintendo introduced a new 16-bit system dubbed the Super Nintendo Entertainment System (SNES). Within a couple of years, rivals had introduced 32-bit systems that eclipsed the capabilities of the SNES. So, Nintendo announced an agreement with Silicon Graphics Inc. (SGI) to develop a new 64-bit video game system, code-named Project Reality. Although SGI had never designed video game hardware before, the company was regarded as one of the leaders in computer graphics technology.

After several years of development, the system was finally released in 1996 as the Nintendo 64. But the delays and shortage of games during the first year of availability gave the advantage to Sony, who had released the PlayStation over a year earlier. Nintendo is facing the same situation again with the Sony PlayStation 2 debuting in 2000, while Nintendo's Gamecube is not due until Fall 2001.

Let's take a look at the components inside an N64, and what their capabilities are. [Be sure to check out How Video Game Consoles Work first for a general introduction to game consoles.]

Processor: 64-bit R4300i "Reality Engine"

Co-Processor: "Reality Co-Processor," 62.5 MHz custom chip that combines the graphics and audio systems.

Graphics: "Reality Immersion Processor"

Audio: "Reality Signal Processor"

Memory: 4 MB Rambus D-RAM (expands to 8 MB)

Operating system: Proprietary

Game medium: Cartridge

Similar to the PlayStation, the CPU in the N64 is a RISC processor. RISC stands for reduced instruction set computer, and means that the instructions and computations performed by the processor are simpler and fewer. Also, RISC chips are superscalar -- they can perform multiple instructions at the same time. This combination of capabilities, performing multiple instructions simultaneously and completing each instruction faster because it is simpler, allows the CPU to perform better than many chips with a much faster clock speed.

To lower production costs, the graphics and audio processors are combined into a single application specific integrated circuit, or ASIC. Simply put, the ASIC which serves as the N64's co-processor is a customized chip created to manage components that would otherwise be handled by multiple chips.

Some special features of the N64 include perspective correction and trilinear mip mapping. Perspective correction makes the texture map resize at the same rate as the object that it is mapped on.

Trilinear mip mapping is a cool process. In this form of texture mapping, three sizes of each texture map are made, a large, a medium and a small version. In essence, it replaces the appearance of an object with a more detailed image as you move closer to the object in the game. Let's take a look at how it uses these maps:

Environment mapping is no less amazing. Simple in concept, it means that reflections of objects are rendered and mapped onto the reflecting surface. The sheer amount of calculating that is done by the graphics processor to determine the angle and transparency for each reflected object, and then render it in real time, is extraordinary. An incredible number of calculations have to happen for every single polygon in a game. And there can be over a hundred thousand polygons on the screen at any given time!

 

The games come on proprietary ROMs housed in plastic cartridges. When a game is put in the console, the following happens:

  

The controller is the primary user interface for the N64. With its trident shape, it is probably the most unusual design for a controller on the market today. The standard N64 controller has 14 buttons plus an analog joystick. The buttons include:

Although each button can be configured to perform a specific and distinctive action, they all work on the same principle. In essence, each button is a switch that completes a circuit when it is pressed. A small metal disk beneath the button is pushed into contact with two strips of conductive material on the circuit board inside the controller. While the metal disk is in contact, it conducts electricity between the two strips. The controller senses that the circuit is closed and sends that data to the N64. The CPU compares that data with the instructions in the game software for that button, and triggers the appropriate response. There is also a metal disk under each arm of the directional pad. If you're playing a game in which pushing down on the directional pad causes the character to crouch, a similar string of connections is made from the time you push down on the pad to when the character crouches.

The analog joystick works in a completely different way from the buttons described above. Two wheels are positioned at right angles to each other below the joystick. Whenever the joystick is moved, the two wheels turn slightly. Tiny slots are arranged around the perimeter of each wheel. The wheels are each mounted between an LED (Light Emitting Diode) and a photo cell. Light from the LED, shining through the slots in the wheel on the cell, creates a small amount of current. When the amount of light changes, the level of current changes. By monitoring the output of each photo cell, the N64 can determine the exact angle at which the joystick is being held, and trigger the appropriate response.

Another feature of the N64 controller is the ability to add options via an expansion slot on the bottom of the controller. A popular option is the Rumble Pak, which provides force feedback. This feature provides a tactile stimulation to certain actions in a game. For example, in a racing game, you might feel a jarring vibration as your car slams into the wall.

Force feedback is actually accomplished through the use of a very common device, a simple electric motor. The shaft of the motor holds an unbalanced weight. When power is supplied to the motor, it spins the weight. Because the weight is unbalanced, the motor tries to wobble. But since the motor is securely mounted inside the Rumble Pak, the wobble translates into a shuddering vibration of the controller itself.

You can save games and high scores by using one of the special Flash memory cards. The card is inserted into the slot on the bottom of the N64 controller.

The N64 controller uses only three wires to connect to the console. There's a ground wire, another wire that supplies +3, 6 volts of power, and a third wire that carries all data. The controller sends the information for each button in sequence, and then receives data back from the console.

The N64 is the only current system that uses cartridges. There are advantages and disadvantages to this approach:

Advantages

Disadvantages

Although the N64 had only a few games available when it first came out, the number of titles has grown to a considerable library. Used games can be found for less than $15. Many of the new games can cost between $50 and $75.

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Special thanks to the staff at BuyRite Video for their assistance with the articles in this series.