Err, you're rather off on early computer history.
TRS-80 was a fairly early computer, sort of ~1978-1981, competing with, and losing to, the Apple II lineup.
For home use, at the time, computers were much cheaper, and didn't really catch on until the TRS-80 line was on fumes, at best. Commodore 64 (circa 1983-1986) was perhaps the most successful in this category, but other competitors included the Atari 400/800 (early) and Atari ST line (later), the Commodore Vic-20 (early), TI 99 4/A (early-ish).
Dell wasn't a major player until somewhat later (1986 fwd, roughly?)
The Mac didn't come out until 1984, and was VERY expensive, for a while.
IBM PC came out in '81 or '82 I think, but didn't really catch on as a HOME computer (including for games) until a bit later - circa 86 and forward. The early IBM PC was very expensive, and had very limited graphics and sound capability. Clones and general cheapening of computers helped on the price, and various better graphics standards (CGA, then EGA, then VGA) helped on that front.
And of course, for games, there were ~dedicated games machines (Atari VCS, Intellivision, etc.) through that era. Some of them tried to cross the other way (keyboard add-ons to become "computers"), but generally with VERY limited success.
The above is a fairly US-centric view. Things were somewhat different in Europe and other places.