[ddp]

VAX/VMS was always open sourced and available first on microfiche and later on CD. I don't know if this continued after Compaq and then HP came to own the code but that's how it started life. The only censored code was the license management facility, which realistically, was trivially subvert-able if you knew VAX assembly language.

[iamcamiel]

This isn't quite correct. What was - and still is - made available to customers willing to pay for it were listings, generated by the compilers, not the original sources. There are more bits and pieces besides LMF that are excluded, sometimes for security reasons, sometimes for legal reasons. Also not made available, are any of the build procedures. What was never done, is release the sources under an open-source license. The source listings are intended as a debugging aid, not as a way to rebuild the OS.

[eej71]

While a factually correct description of what was made available, I don't think that's quite the intended meaning of "open source".

[avian]

"Open source" historically meant just that: that you could look at the source, in contrast to machine code-only software.

Only later did the term got confused with "free software" idea from Stalman and the "preferred form for making modifications" as he put it.

[ams6110]

While "source listings as an aid to debugging" was definitely done, and still is (e.g. Microsoft Windows source is available to researchers), Wikipedia disagrees with the use of the term "open source" as ever meaning this.

The term "open source" was first proposed by a group of people in the free software movement who were critical of the political agenda and moral philosophy implied in the term "free software"

https://en.wikipedia.org/wiki/Open-source_model

[avian]

Interesting. I'm probably confusing some things. I was under the impression that the term "open source" was older than both the free software movement and "open source" as defined by Eric Raymond et al. Not sure where I remember that from. Thanks for correcting me.

[eej71]

That's an interpretation that I had not seen before. You would probably need to provide some more references to evidence for that claim in order to combat the down voting.