The Radio Shack TRS-80 Model 4
List Price: US $999
Release Date: April 1983
The TRS‑80 Model 4, introduced on April 26, 1983, was the continuation of the TRS‑80 computer line that began with the Model I in 1977. The Model 4 was officially launched for the press on April 27 at an event sponsored by the Boston Computer Society.
The Model 4 was 100% compatible with the Model III and was able to run all Model III operating systems and applications. The designers of the Model 4 had taken great pains to ensure this complete compatibility to avoid the same kind of problems encountered when the TRS‑80 Model III was introduced. The Model III had been only partially compatible with Model I software and lack of compatibility was viewed as a costly misstep by Radio Shack. Don White, the Model 4 product line manager, stated, “I took it once on the Model I/III incompatibility and I won’t go through that again.”