Virtual device drivers (also known as VxDs) allow Windows developers to access undreamed of power in their programs. If you want to write programs that have direct access to hardware devices, can interface to vital CPU functions, or can take over parts of the operating system, then welcome to the world of VxDs. Written by experts in the field, David Thielen and Bryan Woodruff, Writing Windows Virtual Device Drivers introduces the concepts of virtual device drivers and shows how to write VxDs in both C and assembly language. Fully-commented complete working source code examples demonstrate how to write a VxD to talk to any hardware device and show the wealth of tricks you can perform with VxDs, including interprocess communication. An extensive appendix provides an encyclopedic reference for the Virtual Machine Manager, the preemptive multitasking kernel at the heart of Windows, and system VxD services and macros. 020148921XB04062001