What does S-80 mean?
“S-80” was a non-trademarked synonym for for the trademark “TRS‑80.” It was usually used to refer to the TRS‑80 expansion bus (“S-80 bus”), but sometimes it was used as an all-encompassing term for the TRS‑80 and compatibles (“S-80 computers”). Other notable uses include the newsletters S-80 Bulletin (originally TRS‑80 Bulletin) and S-80 Computing (originally TRS‑80 Computing) and the magazine Softside: S-80 Edition.
One definition of the term appeared in the March/April 1980 issue of 80-U.S. Journal:
What is an S-80? No, it’s not a new computer— it is the same one you probably own now (the same one that snickered at you while you learned BASIC). 80-U.S. and several other publications are (or have already) adopted S-80 as a designation for the computer we all use and write about, much the same way that S-100 is used to define computers using the S-100 bus. It makes things simple—and you will be seeing this reference often in this and in other publications.
An explanation for the switch was printed elsewhere in the same issue:
It seems that Radio Shack made a fuss about the use of their product name at some recent fairs. The Computer Information Exchange, in their Nov-Dec 79 Bulletin is advocating the usage of S-80 instead of TRS‑80. The situation seems to be a replay of the fuss MITS stirred up with vendors claiming to have products compatible with the “Altair Bus.” Industry responded by renaming the Altair bus “S-100.”
The “fuss” mentioned happened at the Northeast Computer Show in Boston in 1979. The details of exactly what happened are unclear, but three exhibitors were removed from the show. All three exhibitors had been using the word TRS‑80 (a trademarked term) on their items. They were able to return to the show only after either covering the word or by making it clearer that Radio Shack was the trademark owner.
This overzealous enforcement (which might not even have been instigated by Radio Shack) briefly became a public relations problem. But despite widespread fears, it soon became clear that Radio Shack only objected to the use of TRS‑80 in product names, not advertising. As a result, the name “S-80” never really caught on. Almost everyone resumed using TRS‑80, even 80-U.S. Journal and Softside.