Windows 3.1 is fully compatible with most Windows 3.0 device drivers and virtual devices. In most cases, you can continue to distribute your existing driver for use with both Windows 3.0 and 3.1. For some drivers, such as display drivers that utilize font caching, you may need to modify the driver to work properly with Windows 3.1.
To derive the greatest benefit from Windows 3.1, modify your existing driver to incorporate Windows 3.1 features. Modify your driver such that it continues to work properly with Windows 3.0 and 3.1 so that you need maintain only one version of your driver. In all cases, you must thoroughly test your driver with Windows 3.0 and 3.1 and correct any problems.
Although Windows 3.1 does not support real mode, if you create a driver that runs with both Windows 3.0 and 3.1, your driver will need to be a bimodal driver. For more information about bimodal drivers, see the Microsoft Windows 3.0 Device Driver Kit.
If you update your driver, feel free to change description strings to indicate the update, but leave the filename the same as the existing driver. This allows for faster support by Microsoft and your own technical support personnel. In particular, if you are licensing driver files, do not change the driver filenames unnecessarily.