In case you’re not familiar with it or perhaps have confused it in some way with the slightly more famous TRS-80 desktop, the TRS-80 Model 100 (affectionately known among retro-computing buffs as the “T100”) is the Radio Shack-branded version of an early “laptop” computer developed by Kyocera and Microsoft. It was the last system for which Bill Gates wrote a significant amount of code. As we reported in our initial hands-on tour of the Model 100, he considered it his favorite machine ever.
Source: Surfing the Internet… from my TRS-80 Model 100 | Ars Technica