As you know, Windows application has to use APIs to access external Digital I/O or Analog I/O space of PCI expansion boards, for example, and you cannot recognize what's going on until the API returns the result. In this case determinism may not be guaranteed. Unlike a Windows application, an INtime application program can access directly to the I/O space of expansion boards although it runs under RING-3 user mode (protection mode as same as Windows application).
Therefore, you don't have to prepare special driver software for such simple expansion board as DI/O board, for non-intelligent analog boards or for timer/ counter board. You only have to use standard function of C language to execute I/Os without special driver software.