The w11 project uses the pdp11 simulator from the SimH project. The project was started by Bob Supnik under simh.trailing-edge.com, is still maintained, and offers the 3.X stream of SimH releases.
Since about 2014 the project is expanded and continued as GitHub project simh/simh led by Mark Pizzolato. The new, functionally much enhanced, version is called V4.*. However, this project decided not to provide releases anymore, just a stream of commits, more than 4200 as of April 2022.
The maintainer of the simh/simh GitHub project, Mark Pizzolato, decided on May 15th, 2022 with commit ce2adce6 to change the license of the repository. The bottom line of the change is, that some files are declared proprietary and this repository is no longer a FOSS project, see also issue #1163. This triggered massive reactions, see issue #1161 and discussions on the SimH mailing list simh@groups.io, starting with post New license?. See especially Bob Supnik's post SimH licensing and the state of the project.
The post Announcing the Open SIMH project announed on 2022-06-03 a re-launch of SimH as FOSS project. A new repository open-simh/simh has been set up and provides the SimH code-base under an MIT-style licence, see LICENSE.txt. Releases are being prepared, but not offered as of 2023-02-03.
Debian and Ubuntu offer simh packages, but with the obsolete version V3.8.1,
released in February 2009. The main obstacle to the inclusion of newer
versions is, according to the Debian maintainer, the unclear license situation.
The only practical way to obtain an up-to-date SimH PDP-11 simulator is by installation from sources. The currently best solution is to install the latest SimH classic release, URL see above.
The scmd scripts provided in the w11 project were originally developed for
SimH Classic 3.8, and worked for SimH Classic 3.9 and later releases.
They should also work for simh/simh and open-simh/simh, but are currently
most tested with Classic.