Twenty-five years ago, Radio Shack released the first wildly successful laptop computer in the United States. The TRS-80 Model 100 was simple, rugged, plentiful, and reliable, selling over six million units during its eight-year life span. With ample battery life, light weight (about 3 pounds), compact size, instant-on capability, and a small suite of built-in applications, the Model 100 served as the portable computing workhorse of its day. Bill Gates' also ranks it as one of his favorite computers of all time, in large part because he and a friend wrote the firmware it uses.

The Model 100 (not to be confused with the TRS-80 Model 1, one of our 25 greatest PCs of all time) still inspires an awful lot of admiration. PC World chose it as one of the 10 most important laptops of all time. And even though so many were built that it's not highly valuable, it's still one of the most collected of vintage computers. (You can see 18 other digital antique treasures in our slideshow.) And the Model 100 has not one but two active fan clubs, Club 100 and Bitchin 100.

Let's take a look inside this Lilliputian marvel.