README: add Windows instructions

README.md

@@ -12,8 +12,47 @@ NAC3 is packaged using the [Nix](https://nixos.org) Flakes system. Install Nix 2
 
 ## Try NAC3
 
+### Linux
+
 After setting up Nix as above, use ``nix shell git+https://github.com/m-labs/artiq.git?ref=nac3`` to get a shell with the NAC3 version of ARTIQ. See the ``examples`` directory in ARTIQ (``nac3`` Git branch) for some samples of NAC3 kernel code.
 
+### Windows (work in progress)
+
+NAC3 ARTIQ packaging for MSYS2/Windows is not yet complete so installation involves many manual steps. It is also less tested and you may encounter problems.
+
+Install [MSYS2](https://www.msys2.org/) and run the following commands:
+```
+pacman -S mingw-w64-x86_64-python-h5py mingw-w64-x86_64-python-pyqt5 mingw-w64-x86_64-python-scipy mingw-w64-x86_64-python-prettytable mingw-w64-x86_64-python-pygit2
+pacman -S mingw-w64-x86_64-python-pip
+pip install qasync
+pip install pyqtgraph
+pacman -S patch git
+git clone https://github.com/m-labs/sipyco
+cd sipyco
+git show 20c946aad78872fe60b78d9b57a624d69f3eea47 | patch -p1 -R
+python setup.py install
+cd ..
+git clone -b nac3 https://github.com/m-labs/artiq
+cd artiq
+python setup.py install
+```
+
+Locate a recent build of ``nac3artiq-mingw`` from [Hydra](https://nixbld.m-labs.hk) and download ``nac3artiq.zip``. Then extract the contents in the appropriate location:
+```
+pacman -S unzip
+wget https://nixbld.m-labs.hk/build/97899/download/1/nac3artiq.zip  # edit the build number
+unzip nac3artiq.zip -d C:/msys64/mingw64/lib/python3.9/site-packages
+```
+
+Install additional NAC3 dependencies:
+```
+pacman -S mingw-w64-x86_64-lld
+wget https://nixbld.m-labs.hk/build/97899/download/1/mcfgthread-12.dll  # edit the build number
+cp mcfgthread-12.dll C:/msys64/mingw64/bin
+```
+
+And you should be good to go.
+
 ## For developers
 
 This repository contains: