400

The Atari 400, launched in November 1979, was a rugged and affordable home computer built for families and children. It featured a MOS Technology 6502 CPU, advanced ANTIC and GTIA graphics chips, and supported color display and sound far beyond its contemporaries. The 400 came with a sealed membrane keyboard and 8KB of RAM (expandable), while offering full compatibility with the more powerful Atari 800. It supported cartridges, joysticks, and cassette storage, and introduced groundbreaking graphics modes, hardware sprites (Player/Missile Graphics), and multichannel sound. Despite its lower spec and rubbery keyboard, it became a beloved platform for gaming and education.

Notable Features

• Rugged, child-proof case with membrane keyboard
• Full compatibility with Atari 800 software and peripherals
• Cartridge slot for instant loading of games and apps
• Advanced graphics and sound unmatched by most contemporaries
• “Intelligent” SIO port enabled daisy-chaining of printers, disk drives, etc.
• Strong library of educational and arcade-style software

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Historical Significance

• Part of Atari’s 8-bit family, which remained active into the late 1980s
• Introduced hardware concepts (like Player/Missile Graphics) years ahead of rivals
• Atari's first home computer line – leveraged its arcade success to dominate gaming software
• Paved the way for later 8-bit models: Atari 800XL, 65XE, and 130XE
• Influenced console design, especially the use of cartridges and joystick ports

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Collector's Notes

• Rarity: Moderate – more common than the 800, but early boxed units are prized
• Desirability: High among Atari 8-bit collectors and game historians
• Common Issues:
  • Worn or unresponsive membrane keyboards
  • Power regulation failures
  • SIO port cable degradation
• Display Tips: Pair with a 410 recorder, classic Atari joystick, and a cartridge like Star Raiders or Caverns of Mars

Specifications

Technical Information
Name	400
Manufacturer	Atari
Launched	Thursday, November 1, 1979
Discontinued	1983
Launch Price	$549 (8KB RAM version)
Country	United States
CPU	MOS Technology 6502C @ 1.79 MHz (NTSC)
Units Sold
Dimensions	41 cm × 28.5 cm × 9 cm (16.1" × 11.2" × 3.5")
Power	External 9V AC transformer; internal voltage regulation
Expansion	SIO (Serial Input/Output), 2 joystick ports, cartridge slot
Storage	External cassette recorder (410 Program Recorder) or disk drives (810/1050 via SIO)
Keyboard	Membrane (flat panel) keyboard, 57 keys
Sound	POKEY chip – 4-channel audio with random noise generation
Graphics	ANTIC and CTIA/GTIA chips – hardware scrolling, sprites (Player/Missile Graphics)
Display	40×24 text; graphics up to 320×192 resolution, 16 colors
ROM	10 KB (includes OS and Atari BASIC cartridge)
RAM	8 KB standard (expandable to 48 KB via internal upgrade)