And bsd unix, first release around 1977.

The old BSD wasn't freely licensed, though. Some versions included source code, but with no license permitting distribution of derived works.

The first even partial release of a free-software BSD was in 1989, when UC Berkeley first wrote the 4-clause BSD license (with the now-dropped "advertising clause"), and released a non-functioning OS core consisting of TCP/IP stack and libraries, called "Net/1", but couldn't release a functioning OS because they couldn't get permission to release the code that AT&T owned. They rewrote a bunch of the AT&T code as free software and released the first-ever free BSD, Net/2, in 1991, which then led to the 386BSD port, and thence to FreeBSD.

The request was for releases between the founding of the FSF and the release of the Linux kernel. So 1977 was too early to count.

Until Keith Bostic et. al ported it you required a UNIX license from AT&T.

Bostic cites both the GNU project and the GPL as influential.

And Minix (http://en.wikipedia.org/wiki/MINIX) in 1987.

That one also wasn't free software at the time. From the article you link:

  MINIX has been free and open source software since it was released
  under the BSD license in April 2000.

Prentice Hall owned the copyrights. Only after minix lost significant ground to linux was minix released under a different license.

I think that one was one of Tanenbaums great strategic mistakes. The world of software was definitely 'ready' to adopt minix instead of linux (micro kernel, big name behind it), but 'free' won out, and minix is a footnote whereas linux is the unix with the most distribution ever.