NT 3 and 4 Driver Model

[GoBusto]

Hello all,

I seem to recall reading somewhere that early versions of Windows NT (3.x and 4.0) didn't use the WDM design for device drivers. Since VxD was only used by the Windows 9x series and WDF was only introduced fairly recently with Windows Vista, can anyone tell me the name of the driver model used by these versions of Windows?

[Lone_Rifle]

Believe it or not, it was the Windows NT Driver Model, see http://en.wikipedia.org/wiki/Windows_NT#Driver_models

[Ged]

they're known as legacy drivers

[JPLR]

There is a difference between NT3, NT4 WDM in one hand and 2000/XP WDM drivers in the other hand.
The old OSes use the IRP method that originated in DEC's VMS.
Later it was decided that IRP was to much complicated so a new way was devised that was called fastIRP.
In fact it was a complete U-turn toward the Unix way to communicate between kernel and drivers: IRP are asynchronous and not so predictable and it was not easy to use in stacks of drivers like what is common now with anti virus or HID.
This change happens at the same time in NT and OpenVMS.