Atari 7800


The Atari 7800 ProSystem, or simply the Atari 7800, is a home video game console released by Atari Corporation in May 1986 as the successor to both the Atari 2600 and Atari 5200. It can run almost all Atari 2600 cartridges, making it the first console with backward compatibility. It shipped with a two button controller, instead of the 2600-standard Atari CX40 joystick, and with Pole Position II as the pack-in game. The European model has a gamepad instead of a joystick. Most of the early releases for the system are ports of 1981–1983 arcade video games. The final wave of 7800 cartridges is closer in style to what was available on other late 1980s consoles, such as Scrapyard Dog and Midnight Mutants.
Designed by General Computer Corporation, the 7800 has custom graphics hardware similar to early 1980s arcade video games and is a significant improvement over Atari's previous consoles. The same Television Interface Adaptor chip that launched with the Atari VCS in 1977, included for compatibility with cartridges for that system, is used to generate two-channel audio for 7800 games. In an effort to prevent the flood of poor quality games that contributed to the video game crash of 1983, cartridges had to be digitally signed by Atari.
The Atari 7800 and an initial batch of games were first announced by Atari, Inc. on May 21, 1984, but general release was shelved after the purchase of Atari by Jack Tramiel who re-established the company as Atari Corporation. Support for the 7800, along with the 2600 and Atari 8-bit computers, was dropped on January 1, 1992.

History

The Atari 7800 ProSystem was the first console from Atari, Inc. designed by an outside company: General Computer Corporation. It was developed in 1983–84 with an intended mass market rollout in June 1984, but was canceled after the sale of the company to Tramel Technology Ltd on July 2, 1984. The project was originally called the Atari 3600.
With a background in creating arcade games such as Food Fight, GCC designed the new system with a graphics architecture similar to arcade machines of the time. The CPU is a slightly customized 6502 processor, the Atari SALLY, running at 1.79 MHz. By some measures the 7800 is more powerful, and by others less, than the 1983 Nintendo Entertainment System. It uses the 2600's Television Interface Adaptor chip, with the same restrictions, for generating two channels of audio. Audio capability can be expanded via the cartridge port's audio line—with a sound chip in the cartridge—but this was only done in a few games.

Launch

The 7800 was announced on May 21, 1984. Thirteen games were announced for the system's launch: Ms. Pac-Man, Pole Position II, Centipede, Joust, Dig Dug, Nile Flyer, Robotron: 2084, Galaga, Food Fight, Ballblazer, Rescue on Fractalus!, Track & Field, and Xevious. It was a significant technological leap over the Atari 2600 and Atari 5200.
On July 2, 1984, Warner Communications sold Atari's Consumer Division to Jack Tramiel. All projects were halted during an initial evaluation period. GCC had not been paid for their development of the 7800, and Warner and Tramiel fought over who was accountable. In May 1985, Tramiel relented and paid GCC. This led to additional negotiations regarding the launch titles GCC had developed, 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 in warehouses until it was introduced in January 1986.
The console was released nationwide in May 1986 for $79.95 with games intended for the 7800's debut in 1984. It was aided by a marketing campaign with a budget in the "low millions" according to Atari Corporation officials. This was substantially less than the $9 million spent by Sega and the $16 million spent by Nintendo. The keyboard and high score cartridge planned by Warner were cancelled. The 7800 addressed many of the most common complaints with the preceding 5200, including a smaller size, built-in backward compatibility, and an improved controller design.
In February 1987, Computer Entertainer reported that 100,000 Atari 7800 consoles had been sold in the United States, including those which had been warehoused since 1984. This was less than the Master System's 125,000 and the NES's 1.1 million. Games were slowly released: Galaga in August, followed by Xevious in November. By the end of 1986, the 7800 had 10 games, compared to Sega's 20 and Nintendo's 36. Atari would sell over 1 million 7800 consoles by June 1988.
The Atari 7800 was released in the UK in September 1989 at the price of £69.95. It was supplied with two joypad controllers.

Discontinuation

On January 1, 1992, Atari Corporation announced the end of production and support for the 7800, 2600, and the 8-bit computer family including the Atari XEGS. At least one game, an unreleased port of Toki, was worked on past this date. In Europe, last stocks of the 7800 were sold until summer/fall of 1995.
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
  • * 1.79 /1.77 MHz, which drops to 1.19 /1.18 MHz when the Television Interface Adaptor or 6532 RAM-I/O-Timer chips are accessed
  • * Unlike a standard 6502, SALLY can be halted in a known state with a single pin to let other devices control the bus.
  • * Sometimes referred to by Atari as "6502C", but not the same as the official MOS Technology 6502C.
  • RAM: 4 KB
  • ROM: built in 4 KB BIOS ROM, built in 16 KB BIOS + Asteroids ROM, 48 KB General Purpose space without bank switching
  • Graphics: MARIA custom chip
  • * Resolution: 160×240 or 320×240
  • * Color palette: 256, different graphics modes restricted the number of usable colors and the number of colors per sprite
  • * Direct Memory Access
  • ** Note: DMA Modes 0 and 1 shouldn't be used, as this can break the console.
  • ** Programmers should instead use DMA Mode 2, or DMA Mode 3 to disable DMA.
  • * Graphics clock: 7.16 MHz, 7.09 MHz
  • * Line buffer: 200 bytes, 160 sprite pixels per scanline, up to 30 sprites per scanline, up to 100 sprites on screen
  • * Sprite/zone sizes: Up to 32 bytes in width, height of 1 to 16 pixels
  • * Colors per sprite: 1 to 12
  • * Video Modes:
  • ** 160A - 160-pixel mode, 2bpp Sprites, up to 128-pixel wide sprites, all 25 colors available
  • ** 160B - 160-pixel mode, 4bpp Sprites, up to 64-pixel wide sprites, all 25 colors available
  • ** Read Mode 1 doesn't exist
  • ** 320D - 320-pixel mode, 1bpp Sprites, up to 256-pixel wide sprites, 7 colors available
  • ** 320B - 320-pixel mode, 2bpp Sprites, up to 128-pixel wide sprites, 7 colors available
  • ** 320A - 320-pixel mode, 1bpp Sprites, up to 256-pixel wide sprites, 9 colors available
  • ** 320C - 320-pixel mode, 2bpp Sprites, up to 128-pixel wide sprites, 9 colors available
  • I/O: Joystick and console switch IO handled by 6532 RIOT and TIA
  • Ports
  • *2 joystick ports
  • *cartridge port
  • *expansion connector
  • *power in
  • *RF output
  • Sound: TIA as used in the 2600 for video and sound. In 7800 mode it is only used for sound.
  • * At least three games include a POKEY sound chip for improved audio.

    Graphics

Graphics are generated by the custom MARIA chip, which uses an approach common in contemporary arcade system boards and is different from other second and third generation consoles. Instead of a limited number of hardware sprites, MARIA treats everything as a sprite described in a series of display lists. Each display list contains pointers to graphics data and color and positioning information.
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 Master System, the processing demands of MARIA result in most games using the 160 pixel mode.
Each sprite can have from 1 to 12 colors, with 3 colors plus transparency being the most common. In this format, the sprite references one of 8 palettes, where each palette holds 3 colors. The background can also be assigned a color. In total, 25 colors can appear on a scan line.
The graphics resolution, color palettes, and background color can be adjusted between scan lines.

Sound

The 7800 uses the TIA chip for two channel audio, the same chip used in the 1977 Atari VCS, and the sound is of the same quality as that system. To compensate, GCC's engineers allowed games to include a POKEY audio chip in the cartridge. Only two official releases from Atari do this: Ballblazer and Commando.
GCC planned to develop a more advanced sound chip, Minnie, which could also be used in 7800 cartridges. This project was cancelled when Atari was sold to Jack Tramiel.

Digitally signed cartridges

In response to the large number of low quality, third party games released for the Atari 2600—a contributing factor to the video game crash of 1983—Atari required that cartridges for the 7800 be digitally signed. When a cartridge is inserted into the system, the BIOS generates a signature of the cartridge ROM and compares it to the one stored on the cartridge. If they match, the console operates in 7800 mode, granting the game access to MARIA and other features, otherwise the console operates as a 2600. This digital signature code is not present in PAL 7800s, which use various heuristics to detect 2600 cartridges, due to export restrictions.