The Atari 400 was an 8-bit home computer released in November 1979. It was based around the MOS 6502 CPU running at 1.8 MHz.
As the 400 was part of the Atari 8-bit family, then it shared the benefit of having custom co-processor chips, which enabled graphics and sound that were much more advanced than other 8-bit machines on the market at the time. It should also be noted that the Atari 8-bit family of home computers were the first to come with custom co-processor chips.
The machine was designed primarily for children with it’s “advanced child-proof design featuring a pressure sensitive wipe clean keyboard”. With a cartridge port under the front cover, enabling the Atari cartridge game library to be accessed easily.
The 400 also had the capability of having access to a series of plug-n-play peripherals such as a tape drive, floppy disc drive or printer for example as the original 400 and 800 models used an Atari SIO serial bus system, which was essentially an early analogue concept of the modern USB system we use today.