Atari 400 / Atari 800 | 1978

 The Atari 8-bit computers were officially released as the Atari Home Computer System and were a series of home computers launched by Atari, Inc. in 1979. The first models, Atari 400 and Atari 800, were introduced. The architecture of these computers was designed around the 8-bit MOS Technology 6502 CPU and three custom coprocessors, supporting features such as sprites, smooth multidirectional scrolling, and 4-channel audio. The graphics and sound were superior to other computers of the time, and video games played a key role in the software library. Star Raiders, a first-person space combat simulator released in 1980, is regarded as a killer app for the platform.

The Atari 800 was the high-end model, while the 400 was available at a lower price. The 400 used a membrane keyboard with pressure-sensitive keys and initially came with only 8KB of RAM. The 800 featured a regular keyboard and a second cartridge slot, with easy RAM upgrades up to 48K. Both models used the same 6502 CPU (1.79 MHz, PAL version 1.77 MHz) and coprocessors, including ANTIC, POKEY, and CTIA/GTIA. Plug-and-play peripherals used Atari's SIO serial bus, and the developer of the SIO later co-patented the USB (Universal Serial Bus). The core architecture of the Atari 8-bit computers was reused in the Atari 5200 game console released in 1982, but the two systems' games were not compatible.

The 400 and 800 were replaced by several models in the following years. The 1200XL was released in early 1983 to replace the 800 but was discontinued after a few months, followed by the 600XL and 800XL models later that same year. After Atari was sold and re-established, Atari Corporation released the 65XE (sold as the 800XE in some European markets) and 130XE in 1985. The XL and XE models were lighter, featured two joystick ports, and included Atari BASIC. The 130XE featured 128KB of bank-switched RAM. In 1987, after the Nintendo Entertainment System (NES) reignited the console market, Atari Corporation repackaged the 65XE as a game console, adding an optional keyboard and releasing it as the Atari XEGS. This system was compatible with 8-bit computer software and peripherals.

The Atari 8-bit computers were sold in computer stores and department stores like Sears, attracting customers through demos. From late 1979 until mid-1985, about 2 million units were sold. The main competitor was the Commodore 64, released in 1982. In 1992, Atari Corporation officially discontinued all support for the 8-bit line.

In late 1977, Atari began designing a "home computer system." After releasing the Atari Video Computer System (VCS) in 1977, and predicting that the VCS would last around three years, the company began developing a new system to follow. Engineers envisioned a new system that would share similar design principles but address the major limitations of the VCS. The new design brought major improvements in speed, graphics, and sound. Chip development for the system continued until 1978, with one of the most important advances being the CTIA, a new video coprocessor that vastly outperformed the VCS's TIA chip.

During the early development period, the home computer era began with systems like the TRS-80, PET, and Apple II, which Byte magazine referred to as the "1977 Trinity." In 1976, Nolan Bushnell sold Atari to Warner Communications to fund the VCS's launch, and in 1978, Ray Kassar was appointed as CEO. Kassar decided to adapt the chipsets for home computers, believing that this could compete with Apple. To be a home computer, the system had to support text graphics, peripheral expansions, and the BASIC programming language, which was ubiquitous at the time.

The VCS did not support bitmap graphics, and all graphics on the screen were generated by sprites and simple backgrounds, with the CPU loading data into video registers. Atari engineer Jay Miner designed two video chips for the Atari 8-bit computers. The CTIA chip handled sprites and background graphics, while the ANTIC microprocessor completed the screen display. ANTIC fetched scanline data and sent it to the CTIA, which then generated the final color video output.

This system was far more advanced than any system on the market at the time. While Commodore was developing its own video driver, Chuck Peddle, the designer of the MOS Technology 6502 CPU, realized that the Atari design had a competitive edge but could not reveal it due to a confidentiality agreement. Peddle later said, "What Jay did really blew everyone away."

During the design process, two main models were considered: the low-cost "Candy" model and the high-end "Colleen" model, each aimed at different goals. Colleen was intended to be marketed as a computer, and Candy was designed as a game machine or hybrid game console. Colleen offered user expansion slots, two 8KB ROM cartridge slots, RF output, and monitor output, with a full keyboard. Candy had no keyboard and was planned to connect to an external one, originally designed as a game console.

The Atari 400 and 800 were home computer models released by Atari in 1979. The Atari 400 had a membrane keyboard and a door covering a single cartridge slot. The Atari 800 featured two cartridge slots and expansion cards for RAM, ROM, and processors, offering up to 48KB of memory with three 16KB RAM cards. Atari announced its intention to enter the home computer market in December 1978, and the Atari 400 and 800 were unveiled at the Winter CES in January 1979 and released in November of the same year.

Initially, the models were named after their RAM capacities: 400 for 4KB and 800 for 8KB, but due to falling RAM prices, both models were released with 8KB of RAM. Early models used 4kx1 DRAM, and the 800’s user-installable RAM modules had plastic cases, which were later removed due to overheating issues. Eventually, both models were released with maximum RAM capacities of 16KB and 48KB, using 16kx1 DRAM.

Both models supported four joystick ports, allowing up to four players to play simultaneously, but only a few games (such as M.U.L.E.) supported this. Paddle controllers could be connected in pairs, with games like Super Breakout supporting up to eight simultaneous players. The Atari 400, with its membrane keyboard and single internal ROM slot, sold about twice as much as the 800. The 800's right slot was initially produced with one cartridge until March 1983, and later models only featured a single slot.

Creative Computing, in its overview of the 1979 CES, mentioned Atari's machines, describing them as "having fantastic educational, entertainment, and home applications software." In an August 1979 interview, Atari's Peter Rosenthal predicted that demand would be low until 1980-81, estimating that about 1 million home computers would be sold. In an April 1980 issue, Atari's machines were compared to the Commodore PET, mostly focusing on their BASIC dialects. In June 1980, Ted Nelson called the Atari 800 an "amazing graphics box," describing the demo of Star Raiders with "screaming, clapping, and cheering" as an unforgettable experience. He had worked with computer graphics for 20 years but spent an entire night trying to figure out how Atari achieved such performance. He described the machine as "something else" but criticized the lack of developer documentation, concluding that "Atari was like the human body—an excellent machine, but (a) there was no access to the documentation, and (b) I would love to meet the people who designed it." Kilobaud Microcomputing, in its September 1980 issue, praised the Atari 800's performance, graphics, and ROM cartridges but criticized the lack of documentation, warning that the placement of the right Shift key might not be suitable for serious word processing.