DOS users are familiar with the speedup technique of copying ROM BIOS code into RAM where it executes significantly faster, speeding operations - particularly screen updates. Many computers support this feature. Don't enable it if you are running NT because NT reads the BIOS at boot and does not use BIOS functions afterwards. Once NT is loaded, it does not use BIOS functions. NT uses virtual device drivers instead. Implementing BIOS shadowing when you are running NT is RAM wasted.