From Robert X. Cringely’s “Patently Absurd: Why Simply Making Spam Illegal Won’t Work“:
Software patents have become inordinately important for something that 25 years ago we didn’t even believe could exist. After several software patent cases had gone unsuccessfully as far as the U.S. Supreme Court, the general thinking when I got in this business was that software could not be patented, only copyrighted. Like the words of a book, the individual characters of code could be protected by a copyright, and even the specific commands could be protected, but what couldn’t be protected by a copyright was the literal function performed by the program. There is no way that a copyright could protect the idea of a spreadsheet. Protecting the idea would have required a patent.
Then on May 26, 1981, after seven years of legal struggle, S. Pal Asija, a programmer and patent lawyer, received the first software patent for SwiftAnswer, a data retrieval program that was never heard from again and whose only historical function was to prove that all of the experts were wrong — software could be patented. Asija showed that when the Supreme Court had ruled against previous software patent efforts, it wasn’t saying that software was unpatentable, but that those particular programs weren’t patentable.