TRS-80 Micro Computer System

The first widely-successful microcomputer in the North American market, the TRS-80 was distinctive for its design with an included monitor and its ubiquitous presence in Radio Shack stores of the late 1970s and early 1980s. The relative simplicity and popularity of the TRS-80 line led to clones being sold throughout the world. Enormously successful, at launch with over 15,000 pre-orders after it was announced in August 1977, Tandy was able to leverage its network of Radio Shack stores to offer local support and service, something that had been previously unavailable on a nationwide basis in the United States.

The TRS-80 itself was built around a Zilog Z-80 processor, although it was mostly incompatible with the popular CPM-80 operating system and its base of software. The built-in monitor which was basically a simple black and white TV offered a 64x16 text mode. Most games were developed around modifying the character set rather than directly addressing screen locations. The built in BASIC did have a slower access mode which could abritrarily draw points on a 128x48 grid. An unmodified Model I only supported upper-case characters in the default character set. The TRS-80 did not have any built-in sound capabilities although some games would access the cassette port to produce tones which could be heard through a headphone or amplifier. Initial models had only 4K of RAM, although later models would offer up to 128K.

Despite Tandy refusing to sell third-party branded software in its own store or even publish developer documentation beyond the version of BASIC stored in ROM, many games were sold through mail-order and other computer stores. Simple versions of blackjack and backgammon shipped with the original units, but ports of arcade games, popular text games like Zork I and many other titles were available for the system.

Tandy released the Model III in the summer of 1980 which improved the keyboard, added memory, a wider character set and integrated disk drives. Further expansions were available in the Model 4 introduced in 1983, included a portable variant and the ability to support screen resolutions up to 640x240. By 1987 the TRS-80 had largely been removed from Radio Shack catalogs, but variants of the Model 4 could be special ordered as late as 1991.

Note: Only games for the Model I, Model III and Model 4 should be placed on this platform. The Model II was an incompatible machine focused at the business market, and the TRS-80 Color Computer is its own platform. Confusingly, some games refer to being compatible with the TRS-80 Level II, but those were just a 16K variant of the Model I with a newer version of BASIC.