The TRS-80 was the microcomputer Tandy Corporation introduced in 1977 and sold through its Radio Shack retail chain. The preliminary user’s manual archived at the Internet Archive is described as “the original preliminary user’s manual that was shipped with the first 4000 TRS-80 Micro Computers in 1977,” establishing both the product and the year it reached customers. Unlike the build-it-yourself kits that preceded it, the TRS-80 arrived as a finished consumer product: a keyboard, a black-and-white monitor, and a cassette recorder for loading and saving programs.
Inside, the machine was built around the Zilog Z-80 microprocessor, which gave the computer its name. The base Model I shipped with 4K of memory and a built-in BASIC interpreter in read-only memory, so that a buyer could switch the machine on and begin typing programs immediately. Radio Shack’s own technical manual and system documentation, archived alongside the user guide, describe the hardware in detail and served as the reference for the thousands of hobbyists, students, and small businesses who bought the machine.
What made the TRS-80 a mass seller was distribution rather than novelty. It was sold across a national network of Radio Shack stores, which meant that for the first time an ordinary person could walk into a familiar electronics shop and walk out with a working computer. That retail reach is why the TRS-80 is counted, together with the Commodore PET and the Apple II, as one of the “1977 trinity” of machines that turned the personal computer from a kit-builder’s curiosity into a product anyone could buy off a shelf.
The TRS-80 line grew quickly into a family of models and peripherals. Later expansions added more memory, floppy disk drives through an expansion interface, and a wide software library, much of it distributed on cassette and printed as type-in listings in magazines and Radio Shack’s own publications. For a large share of the people who first learned to program in the late 1970s and early 1980s, the TRS-80 was the machine on which they did it.