USB not working or detected in Safe Mode or MS-DOS

Updated: 06/30/2020 by Computer Hope
USB cable and port

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.

If you cannot locate this option in CMOS, and you cannot located USB drivers for your device, contact the computer's hardware manufacturer.


Enabling the option in CMOS only supports computer keyboards and mice, without additional drivers. Other USB devices, such as printer, CD-ROM (compact disc read-only memory), or any other devices may also require additional DOS drivers to be fully detected.