Abstract: An input device emulator comprises an interpreter and a router is provided to a windowed environment. The interpreter reads and interprets commands of a first application program and generates simulated input device messages. The router routes the simulated input device messages to a window sever, which in turn translates the simulated input device messages into simulated input events and forwards them to a second application program. Additionally, the router also routes real input and output device messages between the I/O devices and the window server. At initialization, instances of the router are pushed onto appropriate locations in the various input/output streams of the operating system. Thus, input events are simulated with increased reliability, and without requiring modification to the window server.