Radio Shack was a major player in the early 1980s home computer market. My first computer was a TRS-80 Model 1 with 16K memory and a crude B&W video display. They were also famous for marketing house-branded machines from other companies. This was the case with the TRS-80 Model 100, designed and built by Kyocera.
The $799 Model 100 was introduced in 1983. It offered a 40 character by 8 line screen, 8K memory (enough for about 11 pages of text), ran for 15+ hours on four AA batteries, and featured a built-in 300 baud (approximately 30 characters per second) modem. It included a version of the Microsoft BASIC programming language, and rumor has it this was the last product to feature code crafted by Bill Gates. I've heard similar rumors about the Japanese MSX computer series, though.
The Model 100 was an incredible hit with journalists who quickly realized the power of this early notebook. Stories could be typed up anywhere and transferred back to the publisher using the built-in modem -- a revolutionary approach. Over six million of these portables (and their offspring) were manufactured and they still have legions of dedicated users.
If you'd like to take a Model 100 for a risk-free test drive, Virtual T is a TRS-80 Model 100/102/200 emulator that runs on Windows, Linux, and Macintosh.
Model 100 User's Group (A great starting point for Model 100 information and ideas)
Various Kyocera-made portables (oldcomputers.net)