USB devices not working or being detected in Safe Mode or MS-DOS
Normally, you cannot use USB devices when working in a Real Mode environment (MS-DOS) or Safe mode (in earlier versions of Windows). To do so, you must first install USB legacy emulation drivers, and Legacy USB support must be enabled in CMOS.
Some computer and motherboard manufacturers may have Legacy USB support or USB Keyboard Support in CMOS Setup disabled. If this option is present, verify it is Enabled if you want to enable Legacy USB support.
Note: Enabling the option in CMOS only supports computer keyboards and mice, without additional drivers. Other USB devices such as printers, CD-ROM drives or any other devices may also require additional DOS drivers to be fully detected.
If you are unable to locate this option in CMOS or to obtain legacy drivers for your USB device, contact the computer or hardware manufacturer.