GO.EXE is the usual file name for my Personal Computer software for MS-DOS. The software is custom built to users' requirements using the Opsys software library.
The single program module GO.EXE (or whatever you choose to call it) contains all your Opsys applications; you specify the applications you require through the Change Settings dialog on each PC individually. An activated application runs in a Session, for example:
DDE is particularly relevant where the minicomputer has no native networking capability.
In a Windows MS-DOS Box, press Alt+Enter to switch between a window and full-screen mode.