Any DOS-running PC comes also with BASIC. You can start it with the command
QBASIC
from the DOS command line, or from Windows File Manager (click on an entry QBASIC.EXE, usually located in). If you are a devoted Windows user, you may install an Icon in Program Manager to run BASIC with a click of the mouse.
Correctly written programs halt at the end. But not all programs do that, so an ``emergency exit" is build in.
To stop the execution
of any program, press simultaneously 
+ 
.