Originally Posted by eXeler0
Short question, where is the OS3.9 source (which was extensively modernized over 3.1) kept? Who manages it as we speak?
Short question, long answer coming up. I'll give some context first before finally answering your questions.
The source code of what was sold as AmigaOS 3.5 and 3.9 is not stored in a single repository. This is because for each of these projects a number of developers came together, each of whom contributed to the resulting product.
These projects were managed by Haage & Partner who themselves contributed software to the respective products. From Haage & Partner's perspective the AmigaOS 3.5 and 3.9 updates would consist mainly out of material licensed by third parties, these being Amiga International and the individual developers, respectively.
When Hyperion picked up development work, it licensed the material created by the AmigaOS 3.5 and 3.9 developers, where possible (some did not license their material), as well as the Amiga operating system source code from Amiga, Inc. Haage & Partner chose not to license the code they had produced (they quit the Amiga market shortly after the AmigaOS 3.9 release was complete).
This means that most of the material that was used in AmigaOS 3.5 and 3.9 wound up as the foundations on which AmigaOS4 was built. The gaps left by the material which Haage & Partner and other developers had not licensed for use in AmigaOS4 have been filled by now.
And it's time to answer your questions
The AmigaOS 3.5/3.9 source code which Hyperion has licensed is stored in a subversion repository, along with the AmigaOS4 source code. What exactly happened to the code outside this scope is (at least to me) unclear. Could be that it's sitting on a set of floppy disks, CD-ROMs, Zip or DAT cartridges somewhere in storage. Could be that it's been lost.
To the best of my knowledge, the source code, as stored in the subversion repository for AmigaOS4, is the only copy which is being managed at all. For the time being, I am responsible for keeping it safe and sound.