Released along with the 800 in 1979, the 400 was the low-end model of the two.
The only 8-bit Atari with a membrane keyboard rather than a full-stroke
keyboard. One of the few 8-bit Ataris lacking a composite monitor port.
Originally released with just 8K RAM, but most were sold with 16K RAM. Atari
sold the Atari 400 48K RAM Expansion Kit, which required a little soldering,
to dealers only.
Only the 400 and 800 8-bit Atari models have four controller (joystick) ports.
Early 400 units include the CTIA chip; later units include the GTIA chip, also
present in all later 8-bit Ataris.
Atari marketing used the trademark, The Basic Computer, as an alternative name
for the 400 from 1981-1982.
Production of the 400 ended in May 1983.