You and I are the same age. I too bought Back in Black 40 years ago. Aussie radio has been playing it non stop today; IMHO the second greatest rock and roll band ever.
The Young brothers were truly brilliant; spanning the Easy Beats to Acca Dacca via John Paul Young’s Love is in the Air.
As for 1980, here’s a list of what else was released. Not a good year for Rock. Massive album....
I am also around the same age. I am pretty sure I bought just about every album from 1980, except those from U2, X, XTC, and John and Yoko... I guess I have an aversion to one dimensional acts, or perhaps I am confused by acronyms and initials containing letters beyond "D".