/ _ \_____________/ \
/ _| |_ _ (Δ) \
| |_ X _| |_| |> () (O) |
| |_| __ _ __ (X) |
| / \ |_| / \ |
| _| |_____| |_ |
| / \__/ \__/ \ |
"Welcome the Analog Controller (DUAL SHOCK) the latest sensation in Official PlayStation peripherals and truly feel the power of PlayStation."
The Dual Shock is the iconic PlayStation controller, released halfway through the PlayStation's life, but now one of the most recognizable controllers other than the Atari 2600 joysticks.
1998. Sony is busily promoting their highly successful PlayStation system, heavily promoting the many quality 3-D games on the system. Unfortunately, the original PlayStation controller was heavily cribbed from Nintendo's SNES controller; little was changed beyond a more ergonomic shape and the addition of double triggers. A proper controller for movement in 3-D space needs controls for moving in three axes; up/down, left/right, and forward/backward. Game designers were straining at the limitations of the controller, and Nintendo's oddball Nintendo64 controllers were 3-D ready out of the box.
Sony saw the need for a replacement.
April 2, 1998, Sony announced the Dualshock analog controller, offering "precision analog control" and "realistic force feedback," which went on to be released the next May, coinciding with the release of Gran Turismo (the first game to support it). While this was no big deal at the time, it did allow for more precise control in PlayStation games that took advantage of the analog sticks (basically every game from Q4 1998 on), and also allowed for annoying "force feedback" vibration added to games by designers eager to add extra bullet points to the back of the box.
"Dual Shock" comes from the two new features added to the controller.
"Dual" refers to the two analog thumbsticks, placed in between the udders for gripping the controller. The analog control helped erode the N64's flagging advantage in a handful of genres (particularly racing games), and the dual sticks allowed for game designers to stop using kludges for movement on three axes.
"Shock" came from the vibration feedback, allowed by a pair of small motors inside the controller. When the game designer wanted the controller to shake, he or she could just make it shake. Not really complex, and, generally, less a feature than an annoyance. This was copied from Nintendo's successful Rumble Pak.
A handful of lesser features were added as well. A small button and light between the sticks was added, allowing for the player to turn the sticks on and off. Some games overrode this, leaving the sticks on at all times (a practice that would become common in PlayStation 2 games), and most disabled the joypad if the analog sticks were turned on.
An L3 and R3 button were added; these are under the sticks, and are pressed by pressing on the sticks themselves. Again, these are used more in PlayStation 2 games than in PlayStation games.
Unchanged from the original controller are the joypad, the L1/L2 and R1/R2 triggers on top of the controller, the diamond arrangement of the Δ, , O, and X buttons, and the ubiquitous Select and Start buttons.
An undocumented aspect is the small pack on the cord, near to the plug, which has a small amount of flash ROM. The purpose of this ROM is undocumented, although some games (particularly Madden 2001) have been known to store information on this flash ROM.
This controller was originally gray with dark grey buttons and sticks; this controller is item SCPH-1200, and was packed in with PlayStations in the "PlayStation Dual Shock" release (which was identical to the normal PSX, oher than the controller.) It was discontinued when the PSOne was released, and replaced by item SCPH-110U, which is functionally the same. The only differences are cosmetic, as this version is available in blue, red, green, or white (the latter is packed in with the PSOne), "DUALSHOCK" is printed on the top of the controller, along the seam, and the controller's plug is changed to match with the PSOne's case styling.
This controller was replaced by the Dualshock 2 analog controller, packaged in with the PlayStation 2. The only difference was the color (black), the label (DUALSHOCK 2), and an underutilized feature: all of the buttons have 255 levels of pressure sensativity. Either controller can be used with the PSX, PSOne, or PS2, although the analog button input is exclusive to a Dualshock 2 connected to a PS2.
Thanks to lj, will, and Zerotime for corrections and updates.