Everything mentioned before would be enough to just have the RTOS run beside Windows. However, this would not be sufficient for the daily work because something very important would still be missing: The communication between Windows and the RTOS. RTOS-VM offers two different possibilities for this: TCP/IP based communication via a virtual network between the two OSs and direct access into a common shared memory.
The TCP/IP communication is realized by network drivers. Instead of controlling real existing Ethernet devices, the drivers are working into a shared memory. While the NDIS driver for Windows is part of the product, the RTOS specific driver has to be developed by the customer. This task is very easy because the VMF offers some simple functions for network packet traffic.
The second method of communication consists of direct access into another shared memory, which can be configured in its size. Via existing API-calls on the Windows side as well as on the RTOS side, applications on user mode level can achieve direct memory pointers into the shared memory to manipulate and transfer data from one side to the other. This is supported by bidirectional events which one application can send to the application on the other side to signal that it has changed data (Picture 5.1).
Coexistance Functionality of Windows XP coexisting with a full Real-Time Operating System on a single computer.