Atari 7800

The Atari 7800 ProSystem, or simply the Atari 7800, is a home video game console officially released by the Atari Corporation in 1986. It is almost fully backward-compatible with the Atari 2600, the first console to have backward compatibility without the use of additional modules. It was considered affordable at a price of US$140.

The 7800 has significantly improved graphics hardware over the 2600, but uses the same audio chip. It also shipped with a different model of joystick from the 2600-standard CX40.

The 1986 launch is sometimes referred to as a "re-release" or "relaunch" because the Atari 7800 had originally been announced on May 21, 1984, to replace Atari Inc.'s Atari 5200, but a general release was shelved due to the sale of the company.

History
The Atari 7800 ProSystem was the first game system from Atari Inc. designed by an outside company, General Computer Corporation (GCC). The system was designed in 1983-1984 with an intended mass market rollout in June of '84, but was canceled shortly thereafter due to the sale of the company to Tramel Technology Ltd on July 2, 1984. The project was originally called the Atari 3600, though was later renamed the Atari 7800.

Atari had been facing mounting pressure in the form of competition from the ColecoVision, which boasted graphics that more closely mirrored arcade games of the time than Atari's 2600 system. At the same time, the Atari 5200 (the original intended successor to the Atari 2600) had been widely criticized for not being able to play Atari 2600 games without an adapter.

GCC had a background in creating arcade games and designed their new system with a graphical architecture similar to arcade machines of the time. The 7800 allows a large number of moving objects (75 to 100). Powering the system is a slightly customized 6502 processor, the Atari SALLY (sometimes described as a "6502C"), running at 1.79 MHz. By some measures the 7800 is more powerful, and by others less, than Nintendo's 1983 Famicom.

Launch
The 7800 was initially released in southern California in June 1984, following an announcement on May 21, 1984 at the Summer Consumer Electronics Show. Thirteen games were announced for the system's launch: Ms. Pac-Man, Pole Position II, Centipede, Joust, Dig Dug, Desert Falcon, Robotron: 2084, Galaga, Food Fight, Ballblazer, Rescue on Fractalus!, Track & Field, and Xevious. Atari was a sponsor of the 1984 Summer Olympics and planned to push the 7800 aggressively in time for Christmas that year.

On July 2, 1984, Warner Communications sold Atari's Consumer Division to Jack Tramiel. All projects were halted during an initial evaluation period. Modern publications have often incorrectly asserted that Jack Tramiel mothballed the Atari 7800, feeling video games were a past fad, and subsequently asserted that he dusted off the Atari 7800 once the NES became successful. The reality was that a contractual issue arose in that GCC had not been paid for their development of the 7800. Warner and Tramiel battled back and forth over who was accountable, with Tramiel believing that the 7800 should have been covered as part of his acquisition deal. In May 1985, Jack relented and paid GCC the overdue payment. This led to additional negotiations regarding the initial launch titles that GCC had developed and then an effort to find someone to lead their new video game division, which was completed in November 1985.

The original production run of the Atari 7800 languished on warehouse shelves until it was re-introduced in January 1986, after strong 2600 sales the previous Christmas. The console was released nationwide in May 1986 for $79.95.

Atari's launch of the 7800 under Tramiel was far more subdued than Warner had planned for the system in 1984 with a marketing budget of just $300,000. Additionally, the keyboard and high score cartridge were canceled, the expansion port was removed from later production runs of the system and, in lieu of new titles, the system was launched with titles intended for the 7800's debut in 1984.

By the end of 1986, Computer Entertainer claimed the Atari 7800 had sold 100,000 consoles in the United States, less than the Sega Master System's 125,000 and the Nintendo Entertainment System's 1.1 million. According to Atari, due to manufacturing problems, it only managed to produce and sell 100,000 units by 1986, including units that had been in a warehouse since 1984. A common complaint in 1986 was a lack of games, including a gap of months between new releases (Galaga's release in August was followed by Xevious in November). By the end of 1986, the 7800 had 10 games, compared to Sega's 20 and Nintendo's 36; nine of the NES games were third-party, whereas the 7800 and Master System had no third-party games. A reason cited for the lack of third-party interest in the 7800 was its small 100,000 install base and low market penetration.

Marketplace challenges
Atari's lineup for the 7800 emphasized high-quality versions of popular arcade games like Joust and Asteroids. This had been a primary reason for the success of the Atari 2600, but Joust was four years old in 1986, and Asteroids was seven years old.

During the 7800's life cycle, Atari found themselves struggling to get developers to create 7800 versions of then-popular arcade titles because of a controversial policy employed by Nintendo. When Nintendo entered the industry, it signed up software development companies to create Nintendo Entertainment System (NES) games under a strict license agreement which imposed serious restrictions on what they were allowed to do. One of the key clauses was that companies who made Nintendo games were not allowed to make that game on a competing system for a period of two years. Because of the market success of the NES, companies chose to develop for it first and were thus barred from developing the same games on competing systems for two years. The software libraries of the Atari 7800 and Sega Master System suffered tremendously as a result.

Eleven titles were developed and sold by three third-party companies under their own labels for the 7800 (Absolute Entertainment, Activision, and Froggo) with the rest published by Atari themselves. However, most Atari development was contracted out.

Some NES titles were developed by companies who had licensed their title from a different arcade manufacturer. While the creator of the NES version would be restricted from making a competitive version of an NES game, the original arcade copyright holder was not precluded from licensing out rights for a home version of an arcade game to multiple systems. Through this loophole, Atari 7800 conversions of Mario Bros., Double Dragon, Commando, Rampage, Xenophobe, Ikari Warriors, and Kung-Fu Master were licensed and developed.

Discontinuation
The Atari 7800 remained officially active in the United States between 1986 and 1991 and in Europe between 1989 and 1991. On January 1, 1992, Atari Corp. formally announced that production of the Atari 7800, the Atari 2600, the Atari 8-bit computer line, and the Atari XE Game System would cease. (It has since been discovered that Atari Corp. continued to develop games such as Toki for the Atari 7800 until all development was shut down in May 1993. ) By the time of the cancellation, Nintendo's NES dominated the North American market, controlling 80% while Atari Corp. controlled just 12%.

Despite trailing the Nintendo Entertainment System in terms of number of units sold, the 7800 was a profitable enterprise for Atari Corp., benefiting largely from Atari's name and the system's 2600 compatibility. Profits were strong owing to low investment in game development and marketing.

Retro Gamer magazine issue 132 reported that according to Atari UK Marketing Manager Darryl Still "it was very well stocked by European retail", "Although it never got the consumer traction that the 2600 did, I remember we used to sell a lot of units through mail order catalogues and in the less affluent areas".

Technical specifications

 * CPU: Atari SALLY 6502 ("6502C")
 * Speed: 1.79 MHz, drops to 1.19 MHz when the TIA Television Interface Adaptor or RIOT (6532 RAM-I/O-Timer) chips are accessed
 * (note: Unlike a standard 6502, SALLY can be halted to allow other devices to control the bus)
 * RAM: 4 KB (2 6116 2Kx8 RAM ICs)
 * ROM: built in 4 KB BIOS ROM, 48 KB Cartridge ROM space without bank switching
 * Graphics: MARIA custom chip
 * Resolution: 160×240 (160×288 PAL) resolution or 320×240 (320×288 PAL) resolution
 * Color palette: 256 (16 hues * 16 luma), different graphics modes restricted the number of usable colors and the number of colors per sprite
 * Direct Memory Access (DMA)
 * Graphics clock: 7.15 MHz
 * Line buffer: 200 bytes (double buffering), 160 sprite pixels per scanline, up to 30 sprites per scanline (without background), up to 100 sprites on screen
 * Sprite/zone sizes: 4 to 160 width, height of 4, 8 or 16 pixels
 * Colors per sprite: 1 to 12 (1 to 8 visible colors, 1 to 4 transparency bits)
 * I/O: Joystick and console switch IO handled by 6532 RIOT and TIA
 * Ports: 2 joystick ports, 1 cartridge port, 1 expansion connector, power in, RF output
 * Sound: TIA video and sound chip, same as the 2600. Only the sound is used in 7800 games. Both video and sound are used in 2600 games.
 * Optional POKEY sound chip on cartridge for improved sounds.

Graphics
The graphics are generated by a custom chip called MARIA, which uses an approach common in contemporary arcade system boards. It is very different from other second and third generation consoles. Instead of a limited number of hardware sprites, MARIA allows for a much larger number of sprites described in a series of display lists. Each display list contains sprite entries with pointers to graphics data, color information, and horizontal positioning. The same display list is used for multiple rasters with the pointers being automatically adjusted. However, managing and displaying a large number of sprites required much more CPU time (both directly and indirectly since the MARIA would halt the CPU when drawing sprites) than consoles with hardware sprites and backgrounds.

MARIA supports a palette of 256 colors and graphics modes which are either 160 pixels wide or 320 pixels wide. While the 320 pixel modes theoretically enable the 7800 to create games at higher resolution than the 256 pixel wide graphics found in the Nintendo Entertainment System and Sega Master System, the processing demands of MARIA typically meant that programmers created their games using the lower 160 pixel modes.

Depending on various parameters, each individual sprite can use from 1 to 12 colors, with 3 colors (plus a 4th "transparency" color) being the most common. In this format, the sprite is referenced to one of 8 palettes, where each palette holds 3 assignable colors. There is also an assignable background color, which will be visible wherever another object has not covered it up. In total the system can utilize 25 colors on a scanline at one time.

The graphics resolution, color palette assignments, and background color can be adjusted in between scanlines. This technique is documented in the original 1983 "Atari 3600 Software Guide". Games often used this feature to render high resolution text in one area of the screen, while displaying more colorful graphics with less resolution in the gameplay area. Demos also exist which use this feature to place all 256 colors on the screen at the same time.

The MARIA's approach had advantages and disadvantages when it came to generating graphics in software during the lifespan of the 7800. It excelled at moving around large numbers of sprites on a static screen without the screen flickering that plagued other 8-bit systems. Its flexible design enabled it to play games which used display list manipulation to generate a pseudo 3D appearance such as Ballblazer (1987) and F-18 Hornet (1988). While side-scrolling games in the vein of Super Mario Bros. are possible on the system (1990's Scrapyard Dog is the best example), it is significantly harder to develop such a title than on a tile-based system such as the Nintendo Entertainment System.

Sound
A common criticism of the 7800 regards its use of the TIA to provide 2-channel sound effects and music, resulting in sound quality that is virtually identical to the Atari 2600 VCS from 1977. While the inclusion of 2600 hardware is required to maintain compatibility with the older system, this drove up production costs and reduced available space on the 7800's motherboard. As such, the 7800 does not include additional hardware for generating sound as it does with graphics and the sound hardware is considered the weakest part of the system.

To compensate for this, GCC's engineers allowed games to include a POKEY audio chip in the cartridge which substantially improved the audio quality. To ensure software developers had an economical means of producing better sound than TIA, GCC had originally planned to make a low-cost, high performance sound chip, GUMBY, which could also be placed in 7800 cartridges to enhance its sound capabilities further. This project was cancelled when Atari was sold to Jack Tramiel.

Despite having the capability to support sound chips in cartridges, almost no 7800 cartridges feature POKEY hardware for enhanced sound. Ballblazer, released in 1987, uses the POKEY to generate all music and sound effects. Similarly, Commando, released in 1989, uses a POKEY to generate in-game music while the TIA generates the game's sound effects for a total of 6 channels of sound.

Lockout features
Following the debate over Custer's Revenge, an Atari 2600 VCS title with adult themes, Atari had concerns over similar adult titles finding their way onto the 7800 and displaying adult content using the significantly improved graphics capabilities of the MARIA chip. To combat this, they included a digital signature protection method which prevented unauthorized 7800 games from being played on the system.

When a cartridge was inserted into the system, the 7800 BIOS included code which would generate a digital signature of the cartridge ROM and compare it to the signature stored on the cartridge. If a correct signature was located on the cartridge, the 7800 would operate in 7800 mode, granting the game access to MARIA and other features. If a signature was not located, the 7800 remained in 2600 mode and MARIA was unavailable. All 7800 games released in North America had to be digitally signed by Atari. This digital signature code is not present in PAL 7800s, which use various heuristics to detect 2600 cartridges, due to export restrictions. The signing utility was found and released by Classic Gaming Expo in 2001.

Backward compatibility
The Atari 7800 differs from the 2600 in several key areas. It features a full Atari SALLY 6502 processor whereas the 2600 VCS has a stripped-down 6507 processor running at a slower speed. It has additional RAM (Random Access Memory) and the ability to access more cartridge data at one time than the 2600. The most substantial difference, however, is a graphics architecture which differs markedly from either the Atari 2600 VCS or Atari's 8-bit line of computers.

The 7800's compatibility with the Atari 2600 is made possible by including many of the same chips used in the Atari 2600. When operating in “2600” mode to play Atari 2600 titles, the 7800 uses a Television Interface Adapter (TIA) chip to generate graphics and sound. The processor is slowed to 1.19 MHz, enabling the 7800 to mirror the performance of the 2600's 6507 processor. RAM is limited to 128 bytes found in the RIOT and game data is accessed in 4K blocks.

When in “7800” mode (signified by the appearance of the full-screen Atari logo), the graphics are generated entirely by the MARIA graphics processing unit, all system RAM is available and game data is accessed in larger 48K blocks. The system's SALLY 6502 runs at its normal 1.79 MHz instead of the reduced speed of 2600 mode. The 2600 chips are used in 7800 mode to generate sound and to provide the interfaces to the controllers and console switches.

The Atari 7800 does not support backward compatibility for Atari 5200 games or accessories.

System revisions
Prototypes:
 * Atari 3600, original model number
 * Atari CX-9000 Video Computer System

Production:
 * Atari CX7800, two joystick ports on lower front panel. Side expansion port for upgrades and add-ons. Bundled accessories included two CX24 Pro-Line joysticks, AC adapter, switchbox, RCA connecting cable, and Pole Position II cartridge.
 * Atari CX7800, second revision. Slightly revised motherboard, added an additional timing circuit. Expansion port connector removed from motherboard but is still etched. Shell has indentation of where expansion port was to be.
 * Atari CX7800, third revision. Same as above but with only a small blemish on the shell where the expansion port was.

Peripherals
The Atari 7800 came bundled with the Atari Pro-Line Joystick, a two button controller with a joystick for movement. The Pro-Line was originally developed for the 2600 and was advertised in 1983, but was delayed until Atari proceeded with the 7800. The right fire button only works as a separate fire button for certain 7800 games that utilize it; otherwise, it duplicates the left fire button, allowing either button to be used for 2600 games. In response to criticism over ergonomic issues in the 7800's Pro-Line controllers, Atari later released joypad controllers with European 7800s, which were similar in style to controllers found on Nintendo and Sega Systems. The Joypad was not available in the United States. Due to the unique backward compatibility with the 2600, the 7800's controllers were not compatible with the Sega Master System, nor were Sega's controllers able to use the 7800's two-button mode.

There were few add-on peripherals for the 7800, though its backwards compatibility feature allowed it to use most Atari 2600 peripherals. The XG-1 lightgun, which came bundled with the Atari XEGS, was sold separately for other Atari systems and was fully compatible with the 7800. Atari released five 7800 light gun games: Alien Brigade, Barnyard Blaster, Crossbow, Meltdown and Sentinel.

Canceled peripherals
After the acquisition of the Atari Consumer Division by Jack Tramiel in 1984, a number of planned peripherals for the system were canceled.


 * The High Score Cartridge was designed to save player high scores for up to 65 separate games. The cartridge was intended as a pass-through device (similar to the later Game Genie). Nine games were programmed with the feature but the cartridge was canceled before it was released. In 1999, a limited run of cartridges were produced by Atari historian Curt Vendel using ROM code from Gary Rubio (the former Atari liaison to GCC on the Atari 7800 project). Using the exact circuit design from GCC, Vendel made a perfect functional replica. However this design had a battery design flaw in it. In 2010 Vendel designed his own version using NvRAM and Mark Ball modified the ROM code to make an PAL compatible version. This design has been integrated into the 7800XM Project that Vendel, Ball and other Atari enthusiasts have been working on over several years.  The High Score keeping feature has been included in many homebrew releases in recent years.
 * The 7800 included an expansion port which would have allowed for the addition of a planned computer keyboard, connection to laserdisc players and other peripherals. The expansion port was removed in the second and third revisions of the 7800.
 * A dual joystick holder was designed for games like Robotron: 2084 and future games like Battlezone and others, but not produced.

Software library


While the 7800 can actually play hundreds of titles due to its compatibility with the Atari 2600, there was limited third party support for the 7800 and fewer than 100 titles were specifically designed for it.

Source code release
The source code for 13 games, as well as the OS and development tools (for the Atari ST computer system) were discovered in a dumpster behind the Atari building in Sunnyvale, California. Commented assembly language source code was made available for Centipede, Commando, Crossbow, Desert Falcon, Dig Dug, Food Fight, Galaga, Hat Trick, Joust, Ms. Pac-Man, Super Stunt Cycle, Robotron: 2084 and Xevious game titles.

Emulation and homebrew
When emulators of 1980s video game consoles began to appear on home computers in the late 1990s, the Atari 7800 was one of the last to be emulated. The lack of awareness of the system, the lack of understanding of the hardware, and fears about the digital signature lockout initially caused concerns. Since that time, however, the 7800 has been emulated successfully and is now common on emulation sites. One such program is ProSystem, written in C/C++ for the Microsoft Windows operating system. It uses the Windows API and DirectX to display what it emulates in both PAL and NTSC.

The digital signature long prevented homebrew games from being developed until the original encryption generating software was discovered. When the original digital signature generating software was turned over to the Atari community, development of new Atari 7800 titles began. In addition, the Atari community has slowly uncovered the original 7800 development tools and released them into the public domain. New tools, documentation, source code and utilities for development have since been created which has sponsored additional homebrew development. Several new commercial Atari 7800 titles such as Beef Drop, B*nQ, Pac-Man Collection, Combat 1990, Santa Simon, and Space War have been created and released.

Atari Flashback
In 2004, Atari (now owned by Infogrames) released the first Atari Flashback console. This system resembled a miniature Atari 7800 and joysticks and had 20 built in games (five 7800 and fifteen 2600 titles). While the unit sold well, it was controversial among Atari fans. Atari had given the engineering firm, Legacy Engineering, extremely limited development timelines. The firm was forced to build the Flashback using NES-On-A-Chip hardware instead of recreating the Atari 7800 hardware. As a result, the Flashback has been criticized for failing to properly replicate the actual Atari gaming experience.

Legacy Engineering was later commissioned to create another 7800 project that was subsequently cancelled after prototypes were made.