MACHINE REFERENCE

Atari 400

Name: Atari 400
Brand: Atari, Inc.

The Atari 400 was the cheaper sibling of the Atari 800 in November 1979, with a membrane keyboard, one cartridge slot and the ANTIC and POKEY chips that made the whole Atari 8-bit line.

Why it matters

The 400 put the Atari 8-bit chip set, ANTIC for the display, CTIA for graphics and POKEY for sound, into a $550 machine for families. It also had hardware sprites. The 400 and 800 launched a family that sold about 4 million machines in total and stayed on sale until 1992.

What to check before you buy

Press the membrane keys everywhere. Dead patches are common, and a replacement membrane is the fix.
Check the RAM. A 400 sold with 8 KB is limited, and a 16 KB or 48 KB upgrade makes it far more useful.
Look at the case for yellowing and cracks around the cartridge slot.
Ask whether the power adapter and the controller leads are included.
Test the picture and sound; POKEY and ANTIC faults show up quickly.

Atari 400 computer on display at Musée Bolo

Photo: Rama & Musée Bolo, Wikimedia Commons (CC BY-SA 2.0 fr)

Released

1979

RAM

8 KB at launch; 16 KB later

CPU

MOS Technology 6502B, 1.79 MHz (NTSC) or 1.77 MHz (PAL)

Launch price

$550 (US)

Manufacturer

Atari, Inc.

Form factor

Compact keyboard computer with a membrane keyboard

CPU

MOS Technology 6502B, 1.79 MHz (NTSC) or 1.77 MHz (PAL)

Chipset

ANTIC display processor, CTIA graphics chip (later GTIA) and POKEY sound and input chip

RAM

8 KB at launch; 16 KB later

ROM

10 KB

Graphics

Up to 384 pixels per line, eight hardware sprites (players and missiles), raster interrupts; a palette of 128 colours (16 hues x 8 luminances) on the 400, though some sources quote 256

Audio

Four POKEY oscillators with noise mixing, or two with digital sound

Storage

Cassette (Atari 410), 5.25-inch floppy (Atari 810) and ROM cartridge

Ports

Four joystick ports, Atari SIO serial bus, one cartridge slot, TV output

Atari OS in ROM; Atari DOS on disk

PSU

External power adapter

Units sold

Unknown for the 400 alone; about 4 million for the whole Atari 8-bit family

Successors

Atari 1200XL, 600XL and 800XL (1983)

Membrane keyboard

The 400's sealed membrane keyboard gives no tactile feedback and wears with use. It is fine for games and poor for typing, and a worn one needs a replacement membrane.
Overheating memory modules

Atari's plug-in memory modules were reported to overheat. Check any upgraded RAM and the heat around it.

1979 The Atari 400 and 800 launch in November
1983 The XL series (1200XL, 600XL, 800XL) replaces them
1985 Atari Corporation launches the 65XE and 130XE
1992 The Atari 8-bit line is discontinued