The Radio Shack TRS-80 Color Computer (also marketed as the Tandy Color Computer and affectionately nicknamed CoCo) was one of the earliest of the first generation of computers marketed for home use in English-speaking markets.
Tandy announced the TRS-80 Color Computer on July 31, 1980. The initial model (catalog number 26-3001) shipped with 4K of Dynamic Random Access Memory (DRAM) and an 8k Microsoft BASIC interpreter in ROM. Its price was $399. Within a few months, Radio Shack stores across the US and Canada began receiving and selling the new computer.
Despite bearing the TRS-80 name, the "Color Computer" was a radical departure from earlier TRS-80 Models - in particular it had a Motorola 6809E processor, rather than the TRS-80's Zilog Z80.
The Motorola 6809E was a very advanced processor, but was correspondingly more expensive than other more popular microprocessors. Competing machines such as the Apple II, Commodore VIC-20, the Commodore 64, the Atari 400, and the Atari 800 were designed around a combination of the much cheaper MOS 6502, itself essentially an enhanced clone of the Motorola 6800.
The Tandy Color Computer line started with what is now called the CoCo 1 and ended in 1991 with the more powerful yet similar CoCo 3. All three CoCo models maintained a very high level of software and hardware compatibility, with few programs written for the older model not running on the newer. The converse cannot be claimed, obviously, due to the greater capabilities of the newer CoCo models.
A number of peripherals were available: tape cassette storage, serial printers, a 5.25 inch floppy disk drive, a pen and graphics tablet called the "X-Pad", speech and sound generators, and joysticks.
The CoCo lacked some of the graphics and sound capabilities of other home computers, but made up for it in computing power and ease of programming in BASIC. Combined with the versatile BASIC, the robust, easy-to-interface-to design has long made it an experimenter's favorite. Enthusiasts have continued to affectionately tinker with the "CoCo" to the present day.
The death knell of the CoCo was the advent of lower cost IBM PC clones, the same event that spelled the end of other models competing in the home computer market. On October 26, 1990, Tandy announced that the Color Computer would be dropped from its computer line.
Source: Wikipedia, "TRS-80 Color Computer", available under the CC-BY-SA License.