"Unix came into many CS departments largely because it was the only powerful interactive system that could run on the sort of hardware (PDP-11s) that universities could afford in the mid '70s. In addition, Unix itself was also very inexpensive. Since source code was provided, it was a system that could be shaped to the requirements of a particular installation."
"A Narrative History of BSD by Dr. Kirk McKusick"
https://www.youtube.com/watch?v=ds77e3aO9nA
"Unix came into many CS departments largely because it was the only powerful interactive system that could run on the sort of hardware (PDP-11s) that universities could afford in the mid '70s. In addition, Unix itself was also very inexpensive. Since source code was provided, it was a system that could be shaped to the requirements of a particular installation."
http://www.princeton.edu/~hos/frs122/unixhist/chen.htm