Take the following as truth: I didn't know anyone with a DOS system in the early '80s, but I knew plenty of people with Commodore 64s, TI 99-4As, Apple IIs, computers by Tandy, and even Timex--all with distinct and incompatible operating systems.
Then the following statement: "Nobody used DOS in the '80s." is true, false, or inconclusive?
Answer: Inconclusive