This virtual device becomes active under specific circumstances: Hardware Acceleration is Off:
In the architecture of legacy AutoCAD (particularly versions like AutoCAD 2000, 2000i, and 2002), the software did not always communicate directly with Windows drivers. Instead, it used HDI (Heidi Device Interface) files to bridge the gap. autocad virtual device gdi16.hdi
: If GDI16.HDI is used within AutoCAD, it likely serves as a crucial component in managing graphical output. This could involve functions or definitions that help in rendering drawings, handling device contexts, or supporting the creation of graphical elements through GDI functions. handling device contexts