[tamlin]

Microsoft had a research version of the CLR called Rotor (2002) that predated Mono (2004). Rotor built for Windows, FreeBSD, and macOs, albeit with a not-very-open license.

When Mono came along, the internal position at Microsoft was surprisingly positive. There was a dev slide deck that went into Mono in some depth. And a telling slide that said it wasn't a threat because the performance wasn't competitive at the time.

https://en.m.wikipedia.org/wiki/Shared_Source_Common_Languag...

https://en.m.wikipedia.org/wiki/Mono_(software)

[caspper69]

Rotor was BSD licensed, so I suppose if that’s your definition of a not very open license…

[tamlin]

Rotor had it's own license:

https://en.wikipedia.org/wiki/Shared_Source_Common_Language_...

I have various snapshots of the Rotor 1 and 2 sources around and they have the SSCLI license. There is a file that contains BSD licensed code (pal\rotor_pal.h).

[dcrazy]

Was it originally BSD-licensed, or did it start out as the MS Public Source License or whatever it was called?

We could go back and check on Codeplex… oh wait.