From Computer History Wiki
2.11BSD is a release of UNIX for the PDP-11 by a consortium of CSRG and the USENIX Association. It only run on PDP-11 models with Supervisor mode. It started out basically the same as 2.10BSD, with some upgrades. This version is still getting updates and improvements today.
Some of the things that were added were:
- Support for full 4.3BSD networking (using Supervisor mode)
- Support for long filenames
- 4.3BSD applications that were missing from 2.10BSD
- 2.11BSD - 2.11BSD at TUHS
- Installing and Operating 2.11BSD on the PDP-11 - not in the most obvious place