Atari 2600 hardware: Wikis


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The Atari 2600 video game console with its joystick controller sitting atop

The Atari 2600 went through many makeovers and revisions in its 14 year history. The system also contained a large number of controllers and third-party peripherals.


Technical specifications

  • CPU: 1.19 MHz MOS Technology 6507
  • Audio + Video processor: TIA
  • RAM (within a MOS Technology RIOT chip): 128 bytes (additional RAM may be included in the game cartridges)
  • ROM (game cartridges): 4 kb maximum capacity (32 kb+ with bank switching)
  • Input (controlled by MOS RIOT):
    • Two screwless DE-9[1] controller ports, for single-button joysticks, paddles, "trakballs", "driving controllers", 12-key "keyboard controllers" (0–9, #, and *) and third party controllers with additional functions
    • Six switches (original version): Power on/off, TV signal (B/W or Color), Difficulty for each player (called A and B), Select, and Reset. Except for the power switch, games could (and did) assign other meanings to the switches. On later models the difficulty switches were miniaturized and moved to the back of the unit.
  • Output: B/W or Color TV picture and sound signal through RCA connector (NTSC, PAL or SECAM, depending on region; game cartridges are exchangeable between NTSC and PAL/SECAM machines, but this will result in wrong or missing colors and often a rolling picture.)


Paddle controllers

The Atari had a large number of input devices (such as joysticks, paddles, keyboards, etc...) as well as third-party components.

The console came packaged with two standard joysticks and a set of paddles. Joysticks, featuring a single button and 4-directional stick, were used by most Atari game and was the predominate input device. Also, the Atari joysticks could be used in MSX and several Japanese computers. It is possible to use the joysticks in Sega systems like the Sega Master System or Sega Genesis in games that only require one button.

Standard joystick

The other main controller, the paddle, was used for games based on one-dimensional movement. These included Pong, Breakout, and Circus Atari, to name a few. The "driving controller" appeared similar in design to the paddle, but there was only one per DE-9 port rather than two paddles per port. The key difference in function between the paddle and driving controller was that the paddle's wheel had a finite amount it would turn before hitting a stop, while the driving controller's wheel could rotate continuously. This was essential for overhead-view driving games, for which you would have to turn the wheel a total of 360 degrees in one direction every lap.

Console models


Six switch models

There were two different designs for the six switch models. Both designs incorporated a switch board and a motherboard which were connected by a 12-pin ribbon cable.[2]

CX2600 Sunnyvale

The 1977 Sunnyvale "Heavy Sixer"

For their first year of production (1977), Atari manufactured the CX2600 with heavy aluminum radio frequency shielding as well as 1/2 inch thick plastic bottom half. These units are easily differentiated from other years of production by their thick molding on the sides of the case, the curved molding on the front of the unit, as well as their heavier weight, giving them the nickname "Heavy Sixer".[2]


The CX2600 "Light Sixer"

These models were introduced in 1978 and stayed in production for about two years. The thick molding on the sides and curved molding on the front gave way to thinner and more sharply angled molding reducing the weight of the system. The front right and left molding are angular and overlap the woodgrain. The thick RF shielding remained until the four switch models came out. Atari also included a channel select switch on the bottom right hand side of these systems for the first time.[2]

Four switch models

These models also had two different designs. For the most part, the only difference between the four switch models and the "Light Sixer" is that there are only four switches and retain much of the same moldings. Instead of having two separate boards connected through a ribbon cable, the CX2600-A had one motherboard.


The 4-switch CX2600-A

These models were introduced in 1980. They are similar to the CX2600 "Light Sixer" except where the two difficulty switches were removed from the front of the console to the back. This left four front switches.

Atari 2600

The Atari 2600 "Darth Vader"

These models were introduced in 1982 and were the first to use "2600" in its name. Besides containing a different logo than earlier models, this model does not have woodgrain on the front and are primarily black, resulting in the nickname of "Darth Vader".[2]

Atari 2600 Jr.

The Atari 2600 Jr.

In 1986, a new version of the 2600 was released (although it was planned for release two years earlier). The new redesigned version of the 2600, unofficially referred to as the 2600 Jr., featured a smaller cost-reduced form factor with a modernized Atari 7800-like appearance. The redesigned 2600 was advertised as a budget gaming system (under $50) that had the ability to run a large collection of classic games.

Motherboard revisions

The motherboard of an 1983 Atari 2600 "Darth Vader" model.
The internals of a CX2600 Sunnyvale "Heavy Sixer".

The Atari 2600 VCS Domestic Field Service Manual describes the differences as follows:[3]

2600A model revisions 1-13
In addition to the component changes, the physical location of several parts has also been changed. Instead of having the right and left difficulty switches placed on top of the game, they are located at the rear of the console next to the game controller plugs. The channel selector switch is also located at the rear of the console. The game cartridge socket is no longer angled, but is mounted vertically on the board.
2600A model differences - revisions 14 and 15
Revisions 14 and 15 contain the model differences described above, and in addition have new components on the TIA lines, LM1 and Sync. There are two IN914 diodes to prevent feedback on the lines and two additional pull-up resistors to insure the signal is at +5v. To compensate for any signal loss, R215 and 217 have been changed to 47K (R215) and 24K (R217).

2600A model differences - revisions 16 and up
Revisions 16 and up contain the model differences described above; they also include a timer chip (A205) added to the reset circuitry of the MPU chip. This chip eliminates the problem of power-on reset failures.

Color palette

The Atari 2600 used different color palettes depending on the television signal format used.[4] With the NTSC format, a 128-color palette was available, while in PAL, only 104 colors were available. Additionally, the SECAM palette consisted of only 8 colors.

The Television Interface Adapter(TIA) chip CO1044(D), CPU chip CO10745, and combination Ram+I/O chip CO10750 are the same used throughout the 2600's production.

Third-party peripherals

  • Starpath Supercharger, a cartridge with a cassette player connector, giving 6 1/8 kb RAM capacity
  • Gameline Master Module, a modem allowing downloads of games from an extensive catalog which could be playable for a limited amount of time.
  • Yoko Game Copier, a device that allows the user to copy the ROM from a cartridge to a blank cartridge. The Yoko Game Copier was distributed by C.K.B. in Europe.


  1. ^ The screwless DE-9 controller ports subsequently became the mechanical/electrical de facto standard for game controllers in the 8-bit and early 16-bit era and were used in most subsequent Atari and Commodore consoles and home computers, among many others including the Sega Genesis.
  2. ^ a b c d "Listing of games by Atari for all systems". Atari Guide Classic Game Archive. Retrieved 2009-01-02.  Template:Reliable
  3. ^ (PDF) ATARI 2600/2600A VCS Domestic Field Service Manual; FD100133. Rev.02. Atari. 1983-01-21. Retrieved 2009-01-02.  
  4. ^ Atari 2600 "TIA color chart".



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