A Note on Downloads for Microsoft Windows Windows may mark packages (tarballs and the like) as "contaminated" when downloaded from a browser (they want developers distributing software from their App Store). But the packages can be safely downloaded with these commands from a command prompt window without any problem: For Intel x86_64 PreBuilt: curl -O https://acdl.mit.edu/ESP/PreBuilts/ESP126-win-x64.exe -o ESP126-win-x64.exe or curl -O https://acdl.mit.edu/ESP/PreBuilts/ESP126-win-x64.zip -o ESP126-win-x64.zip For build from source: curl -O https://acdl.mit.edu/ESP/ESP.tgz -o ESP.tgz -- and (for Intel x86_64) -- curl -O https://acdl.mit.edu/ESP/OCC781-win-x64.zip -o OCC781-win-x64.zip