What was invented in the 80's?
The Cellphone and computer were invented in the 80s
Both of those are correct spellings. Formally, it is 1980s but many people spell it as 80s because it is shorter and faster to write. We usually say 80s when we are talking about the previous 80s. For example, when it is 2190, we will call the 2180s the 80s and in the year 1490, they also called the 1480s the 80s. I hope this helps you.
If you want to get technical, it was in the 1940s. it was the size of a small house. see http://en.wikipedia.org/wiki/ENIAC if you are thinking computers roughly the size you see them today, the answer could be argued between the 70s 80s and 90s. in the 70s you had the Xerox Alto, in the 80s you have the Macintosh and the IBM PS/2, 90s is when you start seeing more modern things though.
As a series, it did technically begin "in the 80s" but considering only one episode aired in that decade (December 17th 1989), the phrase in the 80s is being used very loosely. - However, The Simpsons did air as commercials bumpers on The Tracy Ullman Show which began in 1987, so The Simpsons, just not the show, did have their debut in the 80s.