• CPU: Motorola 6502C (8-bit) 1.79 MHz
• RAM: 32 KB
• Resolution: 320 x 200
• Colors: 256, 16 on-screen

Currently, MESS supports the following Atari 7800 versions:

• a7800 [Atari 7800 (NTSC)]
• a7800p [Atari 7800 (PAL)]

Both drivers require a “cartridge” (cart) to run, in .a78 format. You can start the emulation with

mess a7800 -cart "C:\pathtogame\gamename.a78"

On the console, four buttons are present: POWER, PAUSE, RESET and SELECT.

The slim controller features a central joystick and two buttons (one at each side of the controller).

Two different versions of the a7800 are supported. You can switch between them, changing the -bios parameter. At command line,

"-bios 0" or "-bios a7800" = Atari 7800

"-bios 1" or "-bios a7800pr" = Atari 7800 (prototype with Asteroids)

Most games work fine, but a few have graphic and playability issues. See a7800.hsi for a full compatibility list.

Originally developed in 1984 as the Atari 3600, the Atari 7800 Prosystem was released to the US market in 1986, in an attempt to compete in a revitalized home videogame market. The 7800 was actually designed by Gencomp as part of a lawsuit settlement (Gencomp had been sued for releasing a speedup chipset for Atari coinop Missile Command).

The 7800 was compatible with pre-existing Atari 2600 game program cartridges, without the need for expansion modules or turning switches, but was also designed to use enhanced 7800-only cartridges such as the pack-in “Pole Position 2”. (n.b., only the 7800-specific cartridges are currently supported in MESS.) Many peripherals, including a computer/keyboard and high score saving cartridge were planned but never released.

Unfortunately for Atari, the system did poorly in the late 1980's market dominated by Nintendo.

www.atari-history.com has this interesting anecdote: “In the summer of 1984 the first 5,000 Atari 7800's had just been built in the new El Paso assembly plant. The production line manager, Brad Saville was eager to meet with Jack Tramiel to show him the new flagship Atari video game console. The meeting ended abruptly as Jack Tramiel was quoted “Get your pollution out of here! We make computers now and we don't want your garbage.” The line manager was fired 2 days later. About 8-9 months later the line manager received a phone call from Atari asking him as to the whereabouts of the die molds for the Atari 7800. The ex-line manager responded that he did in fact know where they were and for $50/hour for about 200 to 300 hours of his time he would remember where they were and find them. The Atari Corp. representative who called was infuriated and informed the former production line manager that Atari's lawyers would be in contact with him. He never heard from Atari again.”

• 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. Plays all 2600 games except 3 or so (which ones?).
• Atari CX7800 Second Revision: 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.

(info on 7800 models from Zube's “Atari 2600/7800 FAQ”)

• The Atari 7800 Page
• Atari2600.com (covers many classical systems)
• Dan B's Atari 7800 Tech Page
• Atari Age
• Atari Museum

• EMU7800
• ProSystem Emulator