Source: http://www.megalextoria.com/wordpress/index.php/2017/05/16/atari-800-2/
The Atari 400 and Atari 800 were both introduced by Atari in 1979. The biggest differences between these two machines were 1) The Atari 400 had a membrane keyboard while the 800 has a full keyboard, 2) The Atari 800 had two ROM/cartridge slots while the Atari 400 only had one, 3) The Atari 800 had more easily accessible RAM expansion and 4) The Atari 800 had additional keyboard and input/output ports. The Atari 800 at $1000 cost nearly twice as much as the Atari 400 and because of this the 400 outsold it two to one, despite the membrane keyboard.
Originally, the 400 and 800 referred to the amount of system memory each machine had. The Atari 400 was originally going to ship with 4k while the 800 would ship with 8k. Because the cost of RAM was dropping quickly at the time, both ended up shipping with 8k. It wasn't long before the Atari 800 was shipping fully expanded with 48k of RAM.
The Atari 400/800 had very advanced graphics and sound capabilities for the time. In fact the Atari 400 was originally marketed as more of a games machine or at least a hybrid games machine/computer. Nothing really came close to these capabilities until the Commodore 64 was introduced in 1982.
The above ad is for the Atari 800 from circa 1980.
Read more: http://www.megalextoria.com/wordpress/index.php/2017/05/16/atari-800-2/
