The Atari 400 was developed primarily as a computer for children and teenegers and introduced around Christmas 1979.
The Atari 400 was an advanced Atari's entry level computer for its time. It has a membrane keyboard to prevent damage from food and small objects, one expansion slot and,
at least initially, a fixed 8k or 16 k of RAM (later expandable to 48 k). The computer was based on Rockwell 6502 CPU with three custom graphics and sound chips - ANTIC (Scrolling, Sprites, Video),
CTIA / GTIA (Color, Sprites, Collisions), POKEY (timers, sound, keyboard, serial I/O). It has a single cartridge port under the front cover.
The Atari 400 had a large assortment of "Intelligent" peripherals which communicated through a custom bus called the "SIO" (Serial I/O). As the Atari 400 did not have a composite
monitor port and could only be connected to a standard TV via is RF modulator cord, the hackers soon learned how to install composite output back to the Atari 400.
The introducing price in 1979 was US$ 550