The DSM-III, published in 1980, established autism as its own separate diagnosis and described it as a “pervasive developmental disorder” distinct from schizophrenia.
The DSM is largely a tool for billing insurance, it has so many different "disorders" listed that everyone falls into at least one category or another at some point in their lives.
Almost. It was declassified as a disease by the American Psychiatric Association in 1973 [1] (and by the American Psychological Association in 1975 [2]), and the DSM-III has been the first edition to not include homosexuality.
It still contained ego-dystonic homosexuality (TL;DR: "I don't want to be gay") - which was opposed by the APA in 1987 [3] - until 1988, with the publication of the DSM-III-R.