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Atari 400

Atari 400 · 1979–1983 · desktop

Specifications

Cpu: MOS Technology 6502B, 1.79 MHz
Ram: max: 16 KB, soldered directly to the board (no memory module bays like the 800) · base: 8 KB (16 KB on later production runs)
Ports: 1x cartridge slot · 4x controller (joystick/paddle) ports · Serial I/O (SIO) bus for disk, cassette, and printer · Monitor and RF video out
Display: ANTIC/GTIA chipset: palette of 256 hues/luminances, 40x24 text, graphics modes up to 320x192
Storage: base: Atari 410 cassette recorder (no internal storage) · options: Atari 810 5.25" floppy disk drive over the SIO bus
Os Support: latest: Atari DOS 2.5 · shipped: Atari BASIC / OS ROM cartridge
Release Price: $549.95 (8 KB configuration)

Variants

Storage

8 KB launch modelOriginal 1979 configuration, sealed membrane keyboard, targeted as the budget entry point below the 800.

16 KB revisionLater production bumped base RAM to 16 KB as prices fell and software demanded more memory.

Upgrade paths

RAM

16 KB by third-party solder-in RAM chip swaps · RAM is soldered to the board, not socketed in modules like the 800, so upgrading means desoldering and hand-wiring new chips rather than plugging in a module.

~$40 for chips

HARD

keyboard

Mechanical keyboard swap via third-party or hobbyist kits · Stock unit shipped a sealed membrane keyboard aimed at durability for a home/game market; hobbyists later fitted mechanical keyboards salvaged from other Atari 8-bit units.

~$30-$60

HARD

storage

Atari 810 (or later 1050) 5.25 inch floppy drive over the SIO bus · SIO daisy-chain made adding a floppy drive plug-and-play compared to the cassette-only base config, though the single cartridge slot and lack of internal memory bays kept the 400 the more limited sibling of the 800.

~$400-$600 at launch for drive and cabling

EASY