Whoa, a lot of text. I love text.

Quote:In the 50s till the 70s-80s it was common for computer programs to be shared with their source code, it was the norm. Everyone had the permission and the ability to modify the software for their specific usage.

That's not as true as it seems. For example, the ENIAC (admittedly, a pre-50s device) became "royalty-free" in the 70s after a long federal court case, including its software (which was far from being an "operating system" as we know it). I would assume that the general availability of software started with the rise of general purpose operating systems which ran on more than one machine, and even then it was not granted to be "shared with the source code". Unisys's operating systems were mostly proprietary, excluding a limited set of sources available to clients (e.g. in OS 2200).

Computer programs were often shared with their source code, operating systems were often tied to the machines that came with it, thus part of the patented product. You might want to consider that the dominating languages were COBOL and some form of machine code though. As all applications can be read "in machine code", those could be read as "open source"... while they, in fact, were not intended to be. The legendary Unix non-license when everyone could just ask for the source code was, in fact, very restrictive: "A source license only would be granted, and the software would be offered as is, with no support, no refunds, no warranty, and no maintenance."

Quote:There were even organizations of users and suppliers that got formed around sharing the softwares such as SHARE and DECUS.

"Sharing an application" does not necesssarily equal "distributing the sources". :-)

Quote:Unix wise, before 1975, all the Research Unix that Bell Labs produced were for internal use only.

Dennis Ritchie and Ken Thompson published a UNIX paper in 1973, but due to restrictions set by Bell they could not sell it to the outside world. Instead they shipped UNIX media for the cost of disks and shipping. V5 UNIX was licensed to educational institutions around the same time. V6 UNIX was the first version to be sold to companies though.

Quote:This was a great move for the university of Illinois because they started working on implementing ARPANET on those Unix machines, creating the RFC 681, for NETWORK UNIX, with FTP and telnet clients. The first Unix later to included them was BSD.

The final version of Telnet was standardized in 1983, a working Proof of Concept was available in late 1969, eight years before BSD. The FTP protocol predates TCP/IP as well. BSD UNIX might have been the first UNIX to include TCP/IP versions of those though. (Citation needed - sorry.)

Quote:As we've said, at those time the source code was available to anyone who got the software, and so it was a great tool to teach in universities.

... if they had a Unix specialist who could install it. The UCB had Ken Thompson for that, other universities might have had bad luck here.

Quote:Before that softwares were not considered nor intellectual property nor copyrightable, they were open ideas for everyone.

In theory, yes (see above for counter-examples).

Quote:In 1991, they got fed up with AT&T and rewrote all the standard Unix utilities under the BSD license so that they would not be tied to any copyright.

They named it 386BSD.

You were mixing up two different operating systems and developer groups ("they") here.

In June 1991, the BSD Networking Tape 2 ("4.3BSD Net/2") was released by the BSD team, containing the first "almost functional" BSD UNIX without AT&T code; portions of that release had to be withheld for licensing reasons. The missing (the legend says: only three) files were rewritten by William and Lynne Jolitz while porting 4.3BSD to the Intel 80386 CPU, resulting in 386BSD (1992). NetBSD and FreeBSD were basically patched 386BSDs as the Jolitz couple did not work fast enough. :-)

Quote:A year before that lawsuit, in 1991, a student named Linus Torvalds was working on a kernel named Linux, a UNIX clone, which he decided to release as free under the license Stallman created

Linux 0.0.1, known as "FREAX" (Linus did not like the name "Linux", I can understand that), was not released under the terms of the GPL. Linux 0.99 (1992) was the first GPL'd Linux version; ironically, it was released when a free BSD was already available. (He later stated that he would instead have used 386BSD if it would have been available in 1991.)

Quote:Still today several operating systems choose to use softwares under the BSD license for the same reasons, macOS and iOS being two well known examples.

This might be related to the fact that Apple incorporated quite a lot of FreeBSD code.

Quote:In 2002 a company named Santa Cruz Operation, SCO, released the source code of some Ancient UNIX relicensed under a BSD license.

Fixed: In 2002, the SCO Group, a renamed Caldera International (some of you might remember Caldera Linux) which was the inofficial successor of Santa Cruz Operation which had dissolved in 2001, relicensed Research Unix V1 to V7 and UNIX/32V under the (rather restrictive) four-clause BSD license which is almost out of use by today.

Quote:SCO was the "first Unix company", founded in 1979 and filled bankruptcy in 2007, it used to port many UNIX softwares to many platforms.

SCO became the official licensor for Unix System V, it was one of many companies who sold SysV-based products. In 1987, they bought Xenix from the other UNIX company, a small hobbyist community named Microsoft ;-), which was later known as OpenServer and is still developed by a company named Xinuos. This SCO was defunct after 2001, the "Caldera-SCO" (see above) later tried to troll IBM and Red Hat.

Quote:Is it outside of the copyright protection, is it in the public domain?

In a number of countries, including Germany, there is no such thing as "copyright" ("Urheberrecht", the "right of the creator", is an only vaguely similar thing) or "Public Domain", rendering this question obsolete for some people.

Quote:The only true way to relinquish a software into the public domain is to do it explicitly via a license such as the CC0, creative common zero or the WTFPL, what the fuck public license.

Note that, unlike other Public Domain licenses, the WTFPL does not have a liability clause so you could still be sued if your WTFPL'd application causes any damage. (Not proven yet.)

Quote:They define free softwares in terms of liberty and not price.

The FSF's definition of liberty restricts the rights of the user to a limited set. FSF licenses are not necessarily free. (But I'm actually one of those WTFPL users, so my view on this might be highly subjective.)

Just my two cents.