This version of ddlabm07 was compiled for DOS with Watcom C version 11 The files ddlabm07_DOS.exe, dos4gw.exe and *.fon must be in the same directory. To run, in the DOS or command line window, enter "ddlabm07_DOS.exe" or .\ddlabm07_DOS.exe (or first change directory to "ddfiles" and enter "..\ddlabm07_Cygwin") DDLab will start in low resolution 640x480. To toggle to full screen and back enter Alt+Enter. In full screen you can change to higher resolution 1024x768 (or medium res 800x600), but change back to low before exiting DDLab. Earlier versions of windows (up to 1998) have an alternative DOS operating system; DDLab runs better in that. Note: because DDLab for DOS has a few drawbacks, Windows users might consider the Cygwin/X version of DDLab. Cygwin/X is a Linux environment running in Windows.