FillPdb can be called in two different ways. Initially, it is called by FillLdb(). It is also a subfunction of OS2_PM_DRV_ENABLE, and as such, it is called at other times by the GRE. The device contexts for the display driver do not require separate physical device blocks. The initial call, however, calls QueryAndSelectNativeMode() to determine which video mode to set, and then switches to that mode by way of SwitchToExtendedGraphicsMode(). After setting the mode, it calls InitialiseVRAM(), which sets up locations in off-screen VRAM for the hardware and software cursor, dithered patterns, the bit-map cache, and the font cache. Next, it calls CreateFontCache(), which sets up the font cache. Finally, it calls InitialiseSeamless to enable the driver's seamless windows capability.