The source can be downloaded from GitHub which I did. The CC65 project includes the assembly tool ca65. A 65C02 assembly compiler that could run on the Mac. Then I needed the missing part of the puzzle. Then I used Visual Studio code from Microsoft. The X16 emulator is available for the Mac. Recently I worked out a way to do development on the Mac. The emulator, ROM, programming guides, etc are available from Github. The Commander X16 project is creating a modern 8-bit hobby computer similar to the Commodore 64. I couldn’t find the tools easily on the Mac so I used my virtual Windows 10 machine. I have been playing around with C64 assembly for a few months and when I discovered the Commander X16 project I wanted to play.