PlayStation 2 (PS2) was one of the most anticipated
products of 2001. The technical features of the PS2 are very
Sony PlayStation 2
In this edition of HowStuffWorks,
you will learn about the development of the PS2, what's inside
the box and how it all works together. You will also learn
about the controller and the games!
In 1988, Sony entered into an
agreement with Nintendo to develop a CD-ROM attachment, known
as the Super Disc, for the soon-to-be released Super
Nintendo. Due to many contractual and licensing problems,
the Super Disc was never released. Instead, a modified version
was introduced by Sony in 1991, as part of a system called the
The PlayStation 2 has two USB
ports and a FireWire
The Play Station read Super Discs, special
interactive CDs based on
technology developed by Sony and Phillips called
CD-ROM/XA. This extension of the CD-ROM format allowed
audio, video and computer data to be accessed simultaneously
by the processor.
The Play Station also read audio CDs and had a cartridge port
for accepting Super Nintendo game cartridges. The original
Play Station was envisioned as the core of a home multimedia
center. Sony only manufactured about 200 of them before
deciding to retool the design.
The new design, dubbed the PlayStation X, or PSX,
dropped the Super Nintendo cartridge port and focused solely
on CD-ROM-based games. The component hardware inside the
console was revamped as well to ensure an immersing and
responsive gaming experience. Launched in Japan in December of
1994, and in the United States and Europe in September of
1995, the PlayStation quickly became the most popular system
Let's take a look at the components
inside a PlayStation 2 console, and what their capabilities
are. (Check out How Video
Game Systems Work first for a general introduction to game
View of the Emotion Engine and Graphic
128-bit "Emotion Engine"
- Processor clock speed: 300 MHz
- Floating point unit (FPU) co-processor operating at
- Bus speed: 3.2 GB per second
- Original Play Station CPU core as I/O processor
- 150 MHz
- Embedded cache
- 4 MB VRAM
- Resolution: 640x480 or 320x240 interlaced
- Colors: 24-bit
(16,777,216) maximum, as well as 16-bit (65,536) mode
- Geometry engine:
- Polygon rendering: 75 million polygons per second
- Audio: SPU2 (+CPU)
- Channels: 48
- Sample rate: 44.1 KHz or 48 KHz
- Memory: 2 MB RAM
- Optical digital output
32 MB RDRAM
system: Proprietary Sony
- Game medium: Proprietary 4.7-GB DVD
- Supports original PlayStation CDs
- Video DVD support
- Audio CD support
- Drive bay (for hard
disk or network
- Other features:
Like the original PlayStation,
the CPU in the PS2 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.
The incredible amount of heat generated by
the processors requires this huge heat sink.
The floating point unit (FPU) is a special processor
that is dedicated to handling complex mathematical equations,
particularly those that include non-integers, numbers
after the decimal point. These calculations are commonly
referred to as floating point operations because the
decimal point can move, or float, depending on the outcome of
the calculation. The complexity of such numbers can create a
tremendous bottleneck if the main processor has to take the
time to perform each calculation. To alleviate this, the
non-integer numbers are sent to the FPU.
The speed with which the FPU can process these calculations
is expressed as floating point operations per second
(FLOPS). A gigaflop is one billion of these. So the
PS2's 6.2-gigaflop FPU can perform 6.2 billion floating point
operations in a second!
The PS2 has several hardware effects that are handled by
the Graphics Synthesizer. They include an alpha
channel, Bezier surfacing, perspective
correction and mip mapping.
The PS2 uses the alpha channel to add transparency
effects to an object. This is a special graphics mode used by
digital video, animation and video games to achieve certain
- 24 bits are
used to define the amounts of red, green and blue, 8 bits
each, needed to create a specific color.
- Another 8 bits are used to create a gray-scale
mask that acts as a separate layer for representing
levels of object transparency.
- The degree of transparency is determined by how dark the
gray in the alpha channel is.
- By making an area of the mask dark gray, you can make an
object appear to be very transparent
- By making it light grey, you can create special fog or
Bezier surfacing is a 3-D
modeling process that calculates how many polygons are needed
to create an object. It bases the number on the level of
detail necessary to make the object appear to be smooth to the
viewer. The PS2 only performs these calculations on
Bezier-surfaced objects that are in the game. Perspective
correction makes the texture
map resize at the same rate as the object that it is
Mip mapping is a cool process. It is a form of
texture mapping whereby different sizes of each texture map
are made. In essence, the processor 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 the PS2 uses
these maps in trilinear mip mapping:
The goal is to
use the smallest texture map possible given the distance that
the object is from the viewer. The smaller the texture map,
the lower the processing load. On nearby objects, however,
small texture maps create a grainy surface that looks bad, so
larger texture maps are used there.
- The system calculates the distance from your viewpoint
to an object in the game.
- The system loads the texture maps for the object. Our
three maps will be 64x64 (large), 32x32 (medium), and 8x8
- The system determines the exact size that the image map
needs to be -- let's say 16x16 for our example here.
- Based on the size, it decides which two texture maps to
use. For our example, it might choose the medium and small
- It then interpolates (averages) between the two
texture maps, creating a custom texture map that is 16x16,
which it then applies to the object.
The controller is the primary
user interface for the PlayStation 2. With its winged shape,
analog controls and abundance of well-positioned buttons, it
is easy to use yet powerful.
The standard PS2 controller has 15 buttons; all of them,
except for Analog, Start and Select are analog. They include:
each button can be configured to perform a specific and
distinctive action, they all work on the same principle. Each
button has a tiny curved disk attached to its bottom. This
disk is very conductive. When the button is depressed, the
disk is pushed against a thin conductive strip mounted on the
controller's circuit board. If the button is pressed lightly,
the bottom part of the curved disk is all that touches the
strip, increasing the level of conductivity slightly. As the
button is pressed harder, more of the disk comes into contact
with the strip, gradually increasing the level of
conductivity. This varying degree of conductivity makes the
- four buttons arranged as a directional pad on the top
- Analog, Start and Select buttons in the top middle
- four action buttons on the top right
- two action buttons on the front left
- two action buttons on the front right
- one analog joystick on the top left
- one analog joystick on the top right
PS2 controllers also have two analog joysticks.
work in a completely different way from the buttons described
above. Two potentiometers, variable resistors, are
positioned at right angles to each other below the joystick.
Current flows constantly through each one, but the amount of
current is determined by the amount of resistance. Resistance
is increased or decreased based on the position of the
joystick. By monitoring the output of each potentiometer, the
PS2 can determine the exact angle at which the joystick is
being held, and trigger the appropriate response. In games
that support them, analog features such as these allow for
amazing control over gameplay.
Another feature of the Dual Shock 2 controller, actually
the reason for its name, is 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. In
the Dual Shock 2 controller, two motors are used, one housed
in each handgrip. The shaft of each 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
controller, the wobble translates into a shuddering vibration
of the controller itself.
The CDs are just as susceptible to scratches and intense
heat as regular audio CDs -- even more so in fact, since a
scratch on a game CD can make it totally unusable.
Games for the PlayStation 2 are coming out at a rapid pace.
Since it will play older PlayStation games as well, it offers
an incredibly large existing game library. Game prices range
from about $20 to $70.