Atari 7800

The Atari 7800 was released in June 1986 as a replacement for the unsuccessful Atari 5200, and as an attempt by Atari to re-establish their market supremacy against Colecovision and Intellivision. The 7800 was designed to address all the shortcomings of the Atari 5200: it was affordable, was almost fully backward-compatible with the Atari 2600, and featured simple digital joysticks.

The system (designed by General Computer Corporation) could be upgraded to a fully fledged home computer, featuring a keyboard that had an expansion port for peripherals such as disk drives and printers. The console also featured a high score cartridge, which was a battery-backed RAM cart designed for storing game scores.

The NTSC 7800 BIOS included code that generated a digital signature of the cartridge ROM and compared it to the signature stored on the cartridge. This allowed the 7800 to determine whether the cartridge was for the 7800 or the 2600 so the console could be locked into the correct mode, and it prevented developers from creating unauthorized games. However, relatively few titles were released by Atari, many of them lacking in features and unpolished.

Unfortunately, by the time the 7800 was released, the Nintendo Entertainment System (NES) had already captured 90% of the market and the rival Sega Master System had taken most of what was left. In 1992, Atari Corporation abandoned the Atari 7800, in addition to the Atari 2600 and the Atari 8-bit computer line, including the Atari XEGS.

Specifications

Processor

• Custom 6502C
• Speed: 1.79 MHz, drops to 1.19 MHz when the TIA or RIOT chips are accessed

RAM

• 4 KB (2 6116 2Kx8 RAM ICs)

ROM

• Built in 4K BIOS ROM
• 48K Cartridge ROM space without bankswitching

Video

• MARIA custom graphics controller
• 160x240 (160x288 PAL) resolution or 320x240/288 resolution
• 25 colour palette out of 256 colours (16 hues * 16 luma)
• Direct Memory Access (DMA)
• Graphics clock: 7.16 MHz

Sound

• TIA (STELLA) video and sound chip
• Optional POKEY sound chip on cartridge for improved sounds

I/O

• Joystick and console switch IO handled byte 6532 RIOT and TIA
• Ports
  • 2 joystick ports
  • 1 cartridge port
  • 1 expansion connector
  • Power in
  • RF output