The TCC-RT readme.txt file says that to run a .btm file using TCC-RT you would use tcc.exe mybatch.btm However, you can also set TCC-RT as the default for .btm files: 1) Install TCC-RT. 2) From a copy of TCC, copy tccbatch.btm to the TCC-RT folder. (If you don't have TCC you can download and run the TCC/LE install. That will create tcstart.btm, tccbatch.btm and tcchere.btm but will not associate .btm files with TCC/LE.) 3) In the navigation panel of Windows Explorer select the TCC-RT folder and shift-right-click. That will open a context menu with Open command prompt here. (You may have to run as Administrator.) 4) In the Windows command prompt window enter tcc tccbatch.btm and press Enter. 5) That will run the program and give you the option to use TCC (RT) as the default for .bat, .btm and .cmd. 6) Exit the Windows command prompt. 7) Double-click on a .btm file to make sure TCC-RT runs it.