 While some software continued to come at no cost, there was a growing amount of software that was for sale only under restrictive licenses.In the early 1970s AT&T distributed early versions of Unix at no cost to government and academic researchers, but these versions did not come with permission to redistribute or to distribute modified versions, and were thus not free software in the modern meaning of the phrase.After Unix became more widespread in the early 1980s, AT&T stopped the free distribution and charged for system patches.