During the same time of the Atari 400's release Atari also came out with it's bigger and more powerful brother system the Atari 800. This system came out of the box with 16k of RAM and a 10k ROM cartridge in the top section behind the cartridge slots. Atari sold model CX853 expansion RAM cartridges or CX801 10k ROM cartridfges that would plug into the extra slots in the system. Owner's could put 3 16K RAM cartridges along with a 10k ROM cartridge in the system to max out the memory to 48k RAM and 10k ROM.
The earlier released systems came with 4 controller ports to commodate earlier games that allowed 4 player action, however as time went by and with more 2 player games emerging on the scene Atari started to release the 2 controller port systems exclusivly. Another big difference between the 2 system is the fact that the Atari 800 came with 2 cartridge ports. Games and 95% of all non game cartridges were designated for the left cartridge port. (Thus why on the black metal back plates on the Atari brand cartridges and games released in the early 80's would say something along the lines of " <<< LEFT CARTRIDGE " on them.
During this system's release some cool add-ons would finally become available for the system including a 5.25" diskette drive for saving documents and programs, a printer to print documents out, even modems so that you could surf the web using cartridges like TeleLink I and II ( as primitive as it was back in the day at $5.00 to $12.00 an hour).
This would be the last system to come out till Atari came out with the " XL" Line of computers. Even though these systems could be used as both a computer system ( and compete against the Commodore 64 ) It was also a powerful video gaming console ( that would later come out in a similar form with some minor programming differences called Atari 5200.)
In 1979, two years after the release of the 2600 Atari took the company to the next level with introducing their first computer gaming system called the Atari 400. The original system came with the console, TV twin lead switchbox, a joystick and a Basic programming cartridge. Being an 8 bit system, the games that were able to be programmed for this system were much more advanced than what was available for the Atari 2600. Along with the fact that the cartridges you bought would have better graphics, many companies would take advanage of the optional Atari 410 cassette drive or the Atari 810 5.25" diskette drive to release their game titles.
Home users also had the option to go out and buy books with assorted games, utility and music programs that could be typed in using the built in keyboard. This would open the door to even more ways for the user to get the most out of their system.
During the release of this system Atari came out with a more power 8-Bit system called the Atari 800. Which would play the same games and the accessories would be inter-changable between the two. However, due to the price of the Atari 800 the 400 out sold the it's bigger brother by nearly 2:1.