Who remembers the Atari 400 and 800 computer video game systems and their successors, the 600XL and 800XL?
The 400 and 800, codenamed "Candy" and "Colleen" respectively (presumably, after two of the company's then-current secretaries), were announced in the early winter of 1979 and were officially released that fall. The 400 had a membrane-type keyboard and only one cartridge slot, while the more-expensive 800 had a proper typewriter-style keyboard and two cartridge slots (one for the BASIC cart and the other for video game carts). This series was well-known for the use of the 65C02 chip; which also turned up in the Nintendo Entertainment System.
The 400 and 800 were replaced during the summer of 1982 with the 1200XL, and then by early winter 1983, with the 600XL and 800XL. Unreleased prototypes on the drawing board that were planned during the sales of the XL range (1983-1985) included the 1200XLD, 1400XL (a replacement for the 1200XL), 1450XLD, 1600XL, 1650XLD and ultimately, the 1850XLD. The "D" in the model nomenclature indicates a floppy disk drive is included.
The 1850XLD was intended to be Atari's first entry into the 16-bit computer market, and Amiga had granted Atari access to the "Lorraine" prototype (Commodore would eventually win out; which meant Atari had to wait until the 1985 launch of the 520ST for its true entry into the 16-bit computer market).
The Atari 5200 was essentially a console-based version of the 400/800/XL series, without the keyboard.
~Ben