> An early use of the word copyleft was in Li-Chen Wang's Palo Alto Tiny BASIC's distribution notice "@COPYLEFT ALL WRONGS RESERVED" in June 1976. Tiny BASIC was not distributed under any formal form of copyleft distribution terms, but it was presented in a context where source code was being shared and modified. In fact, Wang had earlier contributed edits to Tiny BASIC Extended before writing his own BASIC interpreter. He encouraged others to adapt his source code and publish their adaptions, as with Roger Rauskolb's version of PATB published in Interface Age.
https://en.wikipedia.org/wiki/Copyleft#History