[swiftcoder]

> There are only 4 successful general purpose production OSes

Feel like you are using a very narrow definition of "success" here. Is BSD not successful? It is deployed on 10s of millions of routers/firewalls/etc in addition to being the ancestor of both modern MacOS and PlaystationOS...

[eschaton]

What about IBM i and z/OS, and Stratus VOS, and Burroughs MCP, and Tandem GUARDIAN, and VxWorks and OS-9 and… These all not only still exist but run huge transaction volume (for the mainframe and minicomputer systems) and run a huge amount of embedded systems (for the embedded OSes).