Thanks Alex.
To run the network simulator:
mkdir nabusim
cd nabusim
wget https://github.com/GryBsh/NabuNetworkEmulator/releases/download/0.9.9-beta6/nns-linux-x64.zip -O nns-linux-x64.zip
unzip nns-linux-x64.zip
./nns
Run mame as above and the NABU PC will boot up into the emulated NABU Network.
How to build and run on Ubuntu 22.04, for those of us coming in late:
git clone git@github.com:brijohn/mame.git mame-nabu
cd mame-nabu
git checkout nabupc_wip
make -j6
mkdir -p roms/nabupc
cd roms/nabupc
wget 'https://www.nabunetwork.com/download-manager.php?id=2' -O...