Atari's 8-bit home computer line began with the Atari 400 and Atari 800 which were released in November 1979. The line was later expanded to include the more-powerful Atari XL models and then the XE models. Atari's second cartridge-based console, the Atari 5200, is also based on the same hardware, resulting in many games appearing to be identical across all platforms. The Atari 5200 was followed by the Atari XE Game System which is also based on the Atari 8-bit computers.
All models uses the MOS Technology 6502 CPU which is the same type of CPU used in the Atari 2600 and the NES. The computers also includes custom chips like the ANTIC display instruction processor, the CTIA/GTIA GPU and the POKEY audio chip. The Atari 400 and 800 were supposed to have 4kB and 8kB RAM respectively, and the names 400 and 800 were originally decided upon because of this, but both models were released with 8kB of RAM since the price of memory had fallen when they were released. The 400 has a membrane keyboard while the 800 has a regular one. The 800 also has two ROM cartridge slots instead of the single slot in the 400. Despite this, the 400 outsold the 800 somewhat.
In 1982 the 1200XL was released which came with 64kB RAM, a redesigned aluminum case and more custom keys. Some older software was incompatible with the new OS however. A year later the 600XL and 800XL were released which replaced the other models, including the 1200XL. The 600XL had 16kB of RAM and the 800XL had 64kB like the 1200XL did, and used the same general design. A new hardware feature on both these models was the expansion port called the Parallel Bus Interface.
After Atari was acquired by Jack Tremiel in 1985, the 8-bit Atari computers once again got a new hardware revision known as the XE series along with the 16-bit Atari ST computer. XE stands for XL-Enhanced. They have a similar case design to the Atari ST line of computers but are otherwise identical on the hardware level to the old 8-bit computers, except for the newer Enhanced Cartridge Interface instead of the Paralell Bus Interface and the fact that the 130XE had 128kB of RAM.
In 1987, after seeing the success of the NES, Atari wanted back in on the console market. They
used hardware from a 65XE to create what we know today as the Atari XE Game System. It included a detachable keyboard, a joystick, a lightgun and the games Bug Hunt and Flight Simulator II. Instead of cassette tapes or diskettes, the XE Game System uses cartridges like most other home consoles at the time. Because the XE Game System was almost the same hardware-wise as the 65XE, a lot of software and hardware for the Atari 8-bit computers are compatible. The system didn't sell as well as hoped, partly because of bad marketing and the fact that new releases for the system were few and far between.
In 1992, Atari officially dropped support for their entire 8-bit line of machines.
- 400 and 800 (1979) – original machines in beige cases, 400 has a membrane keyboard, 800 has "full-travel" keys, two cartridge ports, monitor output, expandable memory slots (up to 48 KB). Later PAL versions uses the 6502C processor.
- 1200XL (1982) – new aluminum and smoked plastic cases, 64 KB of RAM, only two joystick ports. Help key, four function keys. Older, often improperly written software, caused compatibility problems with the new OS.
- 600XL and 800XL (1983) – replacements for the 400, 800 and 1200XL sans function keys. 600XL had 16 KB of memory, PAL versions had a monitor port, 800XL had 64 KB and monitor output. Both have built-in BASIC and an expansion port known as the Parallel Bus Interface (PBI).
- 800XLF – 800XL with Atari FREDDIE chip and BASIC rev. C. Released in Europe only.
- 65XE and 130XE (1985) – A repackaged 800XLF with new cases and keyboards. The 130XE came with 128 KB of RAM and an Enhanced Cartridge Interface (ECI) instead of a PBI. The U.S./Canadian version of the 65XE has no ECI or PBI.
- XE Game System (1987) – a game machine in a light beige case, with a detachable full-travel but slightly "mushy" keyboard (Atari ST'ish)
- 800XE – the final machine in the series. Styling the same as 65XE and 130XE. A 130XE with 64 KB RAM. Mainly seen in Eastern Europe.
- Prototypes/Vaporware (Never Officially Released)
- 1400XL – Similar to the 1200XL but with a PBI, FREDDIE chip, built-in modem and speech synthesis chip. Cancelled by Atari.
- 1450XLD – basically a 1400XL with built in 5¼″ disk drive and expansion bay for a second 5¼″ disk drive. Code named Dynasty. Made it to pre-production, but got abandoned by Tramiel.
- 1600XL – codenamed Shakti, this was dual-processor system with 6502 and 80186 processors and two built-in 5¼″ floppy disk drives.
- 900XLF – redesigned 800XLF. Became the 65XE.
- 65XEM – 65XE with AMY sound synthesis chip. Cancelled.
- 65XEP – "portable" 65XE with 3.5" disk drive, 5" green CRT and battery pack.
- 1090XL expansion system, 5 slots in a large case (never released, small numbers leaked out)
- 1055 3½" floppy drive
- XF351 3½" floppy drive
- XF354 3½" floppy drive
There were a huge amount of peripherals released for the 8-bit Atari computers including cassette tape drives, 5.25" floppy disk drives, printers and even modems. The most common add-on is probably the different cassette tape drives since many games were released on cassette tapes. The peripherals use the SIO port and can be chained together to have more than one peripheral plugged in at once.