Atari 7800 FAQ
This FAQ is an evolving document. If you have any additions, suggestions or corrections, please email us.
Last modified on January 11, 2011.
General
What cartridges exist for the 7800?
How much are 7800 games worth?
What power supply does the 7800 use and where can I get one?
What power supply does the European 7800 use?
Will Atari 2600 games work on the 7800?
Will 7800 games work on the 2600?
Are 7800 and 5200 games compatible in any way?
Where can I find an Atari 7800 console or games?
Hardware
What are the different 7800 models?
What types of clones exist?
Are there any emulators for the 7800?
What 7800 hardware was announced, but never released?
How do I hook up my Atari to a TV?
Where do I get my 7800 repaired?
Which light guns work with the 7800?
What hardware peripherals exist for the 7800?
What are the specs for the 7800?
Where can I find pinout information?
What are the 7800 cart and expansion port audio specs?
How do I build composite output for my Atari 7800?
How do I convert a Sega Gamepad and Lightgun for use on the 7800?
Software
Where can I download game instructions?
What are the most common and most rare games for the 7800?
Which games use a lightgun?
What 2600 carts do not work on the 7800?
Where can I find a list of cheats and Easter Eggs?
What programming resources are available?
What is the 7800 encryption algorithm?
Is 7800 Impossible Mission really impossible?
Are there any modern/homebrew games for the 7800?
What games use the Pokey sound chip?
What games work with my 2600 joystick?
General
What cartridges exist for the 7800?
32-in-1 (2600 games)
Ace of Aces
Alien Brigade
Asteroids
Ballblazer
Barnyard Blaster
Basketbrawl
Centipede
Choplifter!
Commando
Crack’ed
Crossbow
Dark Chambers
Desert Falcon
Diagnostic Test Cartridge
Dig Dug
Donkey Kong
Donkey Kong Junior
Double Dragon
F-18 Hornet
Fatal Run
Fight Night
Food Fight
Galaga
GATO (prototype only)
Hat Trick
High Score Cartridge
Ikari Warriors
Impossible Mission
Jinks
Joust
Karateka
Klax (prototype only)
Kung-Fu Master
Mario Bros.
Mat Mania Challenge
Mean 18 Ultimate Golf
Meltdown
Midnight Mutants
Missing in Action (prototype only)
Monitor Cartridge
Motor Psycho
Ms. Pac-Man
Ninja Golf
One-on-One Basketball
Pete Rose Baseball
Pit Fighter (prototype only)
Planet Smashers
Pole Position II
Rampage
Realsports Baseball
Rescue on Fractalus (prototype only)
Robotron: 2084
Scrapyard Dog
Sentinel
Summer Games
Super Huey UH-IX
Super Skateboardin’
Tank Command
Title Match Pro Wrestling
Tomcat: The F-14 Fighter Simulator
Touchdown Football
Tower Toppler
Water Ski
Winter Games
Xenophobe
Xevious
How much are 7800 games worth?
It depends on the game. Most games are only worth a few dollars, even if they’re still in the shrinkwrap. The rarest 7800 games might sell for $20-$50 each.
What power supply does the 7800 use and where can I get one?
Unfortunately, the 7800 uses a proprietary power supply that you cannot buy off the shelf. You can find the correct power specs, but the physical tip is proprietary. Here are the specs:
Input: 120VAC 60Hz 15W
Output: 9VDC 1Amp
Polarity: Looking into the power supply, negative is on the left, positive on the right:
_
___| |___
– | 0 0 | +
|_________|
If you cannot find a 7800 power supply but are comfortable with a soldering iron, one possibility is to find similar connectors and solder them onto a more easily-found power supply. Try using an end connector from an old cordless phone battery. Caution: the connector will plug in to the 7800 either direction so one needs to mark polarity correctly.
Another possibility is to buy a more standard jack and just solder it in parallel with the original connector, then buy a power supply at Radio Shack for a few bucks.
One good place to solder alternate power connections is to the two joints on the underside of the board, located near the original power plug (the polarity is easy to follow because the traces from the power and to the barrel capacitor are polarity-marked). Either an external jack (1/8″ mono) can be run through the old jack’s hole (or a vent hole) -or- an internal jack can be installed where convenient such as the thick “strut” near the original hole or on the right side (when facing the unit for play). You can use a 2600 power supply; the only difference is half an amp, which the techies say doesn’t matter much.
Mark Graybill’s site also has a mod for an alternate power supply.
www.atariguide.com produced some new reproduction 7800 power supplies (scroll about half way down the page).
What power supply does the European 7800 use?
Part No. : C024943-309
AC/DC Adaptor
Input:240V~50Hz 15W
Output:DC 9V 1A
To Comply With BS415
Indoor use only with Models PAL 1 7800
WB 9340
Will Atari 2600 games work on the 7800?
The short answer is yes. Most Atari 2600 games will work fine on a 7800. There are a few games that won’t work on certain revisions of the 7800 console.
Will 7800 games work on the 2600?
No. 7800 games are more advanced and will not work on the older 2600 system.
Are 7800 and 5200 games compatible in any way?
No. The cartridge PCB’s are a completely different shape, not to mention the technical differences. There was a 5200 adapter planned for the 7800 at one point but it was never released.
Where can I find an Atari 7800 console or games?
You might find one at your local used video game store, but most don’t carry the 7800. The easiest place online is eBay, you can find systems and games there all the time. There are also a number of Atari dealers on the web.
For the adventurous, try your local flea market or thrift store. This can be the cheapest method, but also the most time consuming.
Hardware
What are the different 7800 models?
There are three basic US (NTSC) models:
Atari CX7800 – Vastly modified and enhanced 2600 model. Two joystick ports on lower front panel. New chipset (except sound chip; pokey chips could be added to carts). Side expansion port for upgrades and computer add ons. Bundled accessories included two CX24 ProLine joysticks AC Adapter, switchbox, RCA connecting cable, and Pole Position II cartridge.
Atari CX7800 – Second Revision. Slightly revised mother board, added an addional timing circuit. Expansion port connector removed from mother board but is still etched. Shell has indentation of where expansion port was to be.
Atari CX7800 – Third Revision. As above but only a small “blemish” mark on shell.
What types of clones exist?
None that we are aware of.
Are there any emulators for the 7800?
Yes, there are several.
MESS
EMU7800
ProSystem
There are many bugs still evident in 7800 emulation.
What 7800 hardware was announced, but never released?
7800 Keyboard, peripherals and computer games designed by GCC. There was also a 7800 adapter for the 5200.
How do I hook up my Atari to a TV?
The audio/video signal is carried in the same RCA cable from the Atari 7800. You need an RF Modulator (TV Switchbox), or an RCA to Coax adapter. The RCA to Coax adapter will give you a cleaner picture and can be purchased at Radio Shack for around $3. Just plug one end into the cable coming from the 7800, and the other end into the Cable jack on your TV.
Where do I get my 7800 repaired?
In general, it is usually more cost effective to buy another console. The cost to ship it out, have it repaired, and get it shipped back would likely be more than a new console.
Which light guns work with the 7800?
There is no light gun made specifically for the 7800. However, Atari’s light gun (model number XG-1) that came with the XE-Game-System works well. Additionally, Best Electronics sells the Best Lightgun which supposedly works well. It is also possible to rewire a Sega lightgun.
What hardware peripherals exist for the 7800?
Very little was specifically made for the 7800. The Atari Proline controllers were sold with the system. Telegames makes a new joystick similar to the original 7800 ProLine controller. Best Electronics sells a lightgun that works on the 2600 and 7800.
What are the specs for the 7800?
CPU: 6502C (custom, NOT 65C02)
RAM: 4K, high speed (mostly VRAM)
ROM: 52K max
Cpu Clock: 1.79 MHz
Graphics Clock: 7.16 MHz
Slot Config: Most CPU lines + video/audio
CPU Avail: over 90%
ROM specs are based on non-bank select scheme, the graphics clock is the master clock used to drive the video chips.
Where can I find pinout information?
Deathskull Laboratories maintains schematics and pinout information.
Joystick Pinouts
2600/7800 pinouts:
_________________
\ o5 o4 o3 o2 o1/
\ o9 o8 o7 o6 /
\___________/
pin # 2600 control 7800 control
1 WHT- Up WHT- Up
2 BLU- Down BLU- Down
3 GRN- Left GRN- Left
4 BRN- Right BRN- Right
5 unused RED- Button (R)ight (-)
6 ORG- Button ORG- Both buttons (+)
7 unused (+5v) unused (+5v)
8 BLK- Ground(-) BLK- Ground(-)
9 unused YLW- Button (L)eft (-)
2600 control (button)
pin 6 ORG(+) ————–()————BLK(-) pin 8
Button
7800 control (buttons)
/———-YLW(-) pin 9
Button L /
/———()—| YLW splits
/ \—-///—–\
pin 6 ORG(+) ——-| ORG splits 620 ohm |—BLK(-) pin 8
\ /—-///—–/
\———()—| 620 ohm
Button R \RED splits
\———-RED(-) pin 5
What are the 7800 cart and expansion port audio specs?
Cartridge Port Audio
The EAUDIO signal on the cartridge port pin 18 is the same audio signal that you hear from your monitor or TV. It is provided to the cartridge port with the idea that cartridges could include the ability to generate their own sound in addition to the sound generated by the 7800 itself. For example, a cartridge could have a POKEY chip on board and it would put its output out on this pin.
Expansion Port Audio
There is no audio signal output on the expansion connector pin 17. Introducing an analog audio signal on this pin produces no results, whether this is because there needs to be a flag set in one of the I/O chips to enable external audio mixing (which I suspect is the case) or whether it is expecting a digital signal, I don’t know.
In any case, you can’t pick up an audio signal from here for a separate audio output.
How do I build composite output for my Atari 7800?
Complete directions for composite output are beyond the scope of this FAQ. Check these examples:
Jay Tilton’s 7800 Chroma/Luma/Audio mod
Mark Graybill’s 7800 Chroma/Luma/Audio (S-video) mod.
How do I convert a Sega Gamepad and Lightgun for use on the 7800?
Deathskull labs has instructions on how to do this.
The Lab Rat page also has instructions for converting the Sega gamepad and lightgun.
Software
Where can I download game instructions?
Digital Press maintains an archive of instruction manuals in both HTML and scanned format.
http://www.digitpress.com/library/manuals/atari7800/index.html
What are the most common and most rare games for the 7800?
This is of course a matter of opinion, but here are some generally accepted examples:
Most common:
Pole Position II (pack-in game)
Most rare:
32-in-1
Sentinel
Mean 18 Golf
Tank Command
Water Ski
Which games use a lightgun?
Sentinel
Alien Brigade (joystick ok)
Barnyard Blaster
Crossbow (joystick ok)
Meltdown
What 2600 carts do not work on the 7800?
There are known incompatibilities with some NTSC versions of the 7800. Games that may not work include Robot Tank, Decathlon, Space Shuttle, Time Pilot, Kool-Aid Man and the Supercharger. In short, 7800s manufactured in 1984 seem to be fully compatible, whereas those manufactured later have inconsistent incompatibilities.
Test decks:
Serial # Board part#
Deck# 72R4BR- Country Expansion port CO25233- Board Date
—– ————- ——- ————– ———– ———-
1 AT 8 5037836 Taiwan Full port 001 REV A 84-25
2 A1 76 5904610 Taiwan Full port 002 REV A 87-17
3 A1 77 5951337 Taiwan Hole/no pins 002 REV A 87-17
4 A3 87 5139813 Taiwan No port 002 REV B 88-28
5 A3 07 5298641 China No port 002 REV B 88-30
Board part number/revision is taken from the underside of the board, just above the cart slot. The full number always begins with “CO25233.” The boards’ top side has a different part number, “CO25234,” but no revision level is given. Board dates are also taken from the underside of the board, near the Atari logo. The notation is changed a bit to make sorting by date easier. They’re really written like “2584” instead of “84-25,” which would indicate the twenty-fifth week of 1984.
The carts tested were:
Decathlon (2 different carts)
Robot Tank (3)
Space Shuttle (5)
Supercharger (2)
7800 Food Fight
Results: “Yes” = cart works fine.
“No” = cart doesn’t do a thing.
“Roll” = cart works, but picture rolls.
“Lock” = cart plays for a while, then locks up the system.
Deck #
Cart 1 2 3 4 5
—— —— —— —— ——
Decathlon 1 Yes No No Yes Yes
2 Yes No No Yes Yes
Robot Tank 1 Yes Roll Roll Roll Roll
2 Yes Yes Roll Roll Yes
3 Yes Yes Roll Roll Yes
Space Shuttle 1 Yes Yes Yes Yes Yes
2 Yes Yes Yes Yes Yes
3 Yes Roll Roll Roll Yes
4 Yes Roll Roll Roll Yes
5 Yes Yes Yes Yes Yes
Supercharger 1 Yes No No No No
2 Yes No No No No
Food Fight Yes Yes Lock Lock Yes
Whether or not a given cart works on a given deck depends on both cart and deck. There’s no real consistency among different carts of the same title. It looks like the Supercharger is the proof test of whether a given deck will be fully compatible with any 2600 cart. The conventional wisdom saying that a deck with the expansion port will work with anything is false. Presence or absence of the port is not a reliable indicator of compatibility with all 2600 carts. Likewise, the deck’s geographical origin is not a reliable indicator. The one manufactured in China (#5) has fewer compatibility problems than the others, but it still has some. The oldest deck (#1) performed flawlessly in all tests. This is probably from the earliest production run, and was either sold in one of the limited test-markets or was warehoused until Atari Corp realized the home video game market was still viable.
The manufacturing standards of deck #1 are better than the others. All the major chips inside are all socketed instead of being soldered directly to the board. Some of the other decks also have had some minor factory patchwork performed. They occasionally have resistors bridging points where they were clearly not originally intended to be, i.e. soldered directly to a chip pin or placed on the underside of the board.
Wondering if that 7800 deck sitting in the thrift store could be one of the fully-compatible ones? There are some very minor externally visible differences between my deck #1 and the others. These may not be 100% reliable indicators, but they are conspicuously different.
The labels on the undersides of decks 2-5 have a box drawn around the serial number. Deck #1 has no box drawn. The serial number itself on deck #1 is different from the others. The “72R4BR” prefix is very much smaller than the rest of the number. “AT85037836” is one continuous string of black characters with no spaces, while on deck #2 (#3-5 are similar), “A1 76 5904610” does have the spaces, and the “76” is stamped in blue. The cart contacts of deck #1 have a definite copper color, while the contacts of the others have a silvery appearance.
Superchargers may be permanently damaged when used on the 7800. Try Robot Tank first and then proceed only if that cart works.
To make your later model 7800 electronically the same as the early model 7800, check out John Soper’s 7800 Compatibility Fixes page.
Where can I find a list of cheats and Easter Eggs?
Digital Press maintains a list of Easter Eggs including some screen shots.
http://www.digitpress.com/eastereggs/7800.htm
What programming resources are available?
John Saeger maintains the Atari Documentation Depot, which contains both 2600 and 7800 programming, development and game standards manuals.
The Atari History Museum has several of the original 7800 (AKA 3600) technical documents on their 7800 page (scroll to the bottom).
Eckhard Stolberg’s VCS Workshop Page also contains many tools and source code files. Of particular interest is devkit2.zip which contains instructions on how to modify a 7800 such that it may be used as a development system and cart reader for 2600 and 7800 games.
There is Harry Dodgson’s Monitor Cart plus documentation. The 250+ pages included a stella guide, a 2600 programming manual which was a bit more readable, the Maria specs, and the 7800 docs plus numerous corrections to the Atari documentation. Video 61, is still producing these in small batches. The price is $99.95.
Dan Boris’ 7800 Tech Page also contains a wealth of information on the 7800.
What is the 7800 encryption algorithm?
The 7800 uses an encryption key to determine whether or not the 7800 cartridge is valid and to allow the system to be put in 7800 mode as opposed to 2600 mode. After much waiting and searching the original encryption generating software was discovered and released by the folks at the Classic Gaming Expo. Shortly after it was released, a new PC version was developed, from the original Atari ST program, by Frank Palazzolo. It is available for download from Dan Boris’ 7800 Tech Page.
Bruce Tomlin has also created a version for use on Linux, source code is available from his website
The reason you need to encrypt the programs is that, as designed, the 7800 required a valid 960-bit digital signature generated by Atari before a native 7800 game (as opposed to a 2600 game) would run on the 7800; no digital signature, no Maria chip. Also, crypto export restrictions (960 bits are a lot even for military-quality crypto) are probably the reason that European 7800 consoles and games have no digital signature.
The final word on the encryption/authentication/validation/signature bits of the 7800 with respect to emulation comes from a section on Dan Boris’ 7800 Tech Page called The Encryption Issue. You’ll have to scroll about half of the way down to read the entry. In short, emulation of the 7800 is independent of the validation key, but the creation of new games that will run on unmodified 7800s isn’t.
Is 7800 Impossible Mission really impossible?
Yes. The cart was released with a bug where some of the pieces you need were hidden under computer terminals, but the terminals cannot be searched. This bug was fixed, but Atari probably never released the updated version. The PAL version is not impossible, as the programmer of the PAL version fixed the bug. A special thanks to Harry Dodgson for this tidbit.
Are there any modern/homebrew games for the 7800?
Yes!
Harry Dodgson has released Combat 1990 through Video 61.
Ken Siders has released Beef Drop (Burger Time clone).
Plus, there are several more games in the works. Stay tuned!
What games use the Pokey sound chip?
Ballblazer uses it for all of the sound in the game.
Commando uses it for the background music.
What games work with my 2600 joystick?
Asteroids
Ballblazer
Centipede
Crossbow (lightgun OK)
Dig Dug
Donkey Kong
Donkey Kong Junior
Fight Night
Food Fight
Galaga
Impossible Mission
Joust
Kung Fu Master
Mario Bros.
Ms. Pac-Man
Pete Rose Baseball
Robotron: 2084
Summer Games
Super Skateboardin’
Title Match Pro Wrestling
Touchdown Football
Tower Toppler
Winter Games