TRS-80 Color Computer

The TRS-80 Color Computer (or CoCo as it is affectionately called by fans of the platform) was an 8-bit computer introduced by Tandy Corporation as an affordable home computer in 1980. Although not aggressively marketed, it was often the best selling computer line during the 1980s at Tandy's Radio Shack stores.

Despite its full name as the TRS-80 Color Computer, the CoCo was completely incompatible with the earlier TRS-80 Micro Computer System, and was based on a Motorola 6809E not the Zilog Z80 which gave the line its name. In fact, the initial architecture and case design of the CoCo was inspired from a terminal co-developed by Motorola that was intended for the agriculture industry. As a result, the CoCo was saddled by not having a dedicated video or audio system like it's competitors from Atari and Commodore. Some of those limitations were mitigated by using the powerful (albeit expensive) 6809.

Designed to be connected to a color television, the CoCo provided several low resolution 4 color modes. It also provided a higher resolution 256x192 in a monochrome mode, which through creative use of artifact effects could be employed as a four color 128x192 mode. This mode became more popular with game developers than the system's built in 4-color modes. Later generations of the CoCo would add custom hardware to overcome some of these limitations, allowing for a composite monitor hookup resulting in a higher resolution (640x225) 16 color mode and faster screen refresh rates. But as with other aspects of the CoCo, the design make the same compromises by sacrificing processor speed to achieve the higher capacity graphics. This handcuffed overall performance and few games used the more advanced modes.

A variety of CoCo clones were produced internationally, and due to its origins in the 6809 reference design plan from Motorola, it often had close compatibility with other platforms. Notably, the Dragon 32/64 could run some CoCo software, often as easily as just reloading the BASIC source onto the Dragon, or vice versa. The same was also true for its more distant cousin, the Fujitsu FM-7/77. The interoperability between the three platforms was enhanced by the fact that all three used variants of Microsoft BASIC rather than vendor specific versions. In addition, they could all run an early multitasking operating system called OS-9 which enforced compatibility despite local hardware differences between the platforms. OS-9 was rarely used for games however.

Unfortunately, the CoCo occupied a peculiar space in Tandy's lineup as the company tried to simultaneously market its more "serious" TRS-80 and later the DOS compatible Tandy 1000. Various design decisions resulted in Tandy deliberately throttling the CoCo's performance so it didn't compete with its siblings for floor space at Radio Shack. The machine's processing potential and long production run did result in a strong user community which continued to support the machine long after Tandy announced the end of the Color Computer in October 1990.

Most software titles for the CoCo are produced on cartridge or cassette tape. While a floppy disk controller and drive was available, it was most often used with OS-9 and few game titles were produced on floppy media.