I have no UEFI/Legacy BIOS boot option. What does that mean? - Super User
How to Convert UEFI to Legacy BIOS on Windows (7, 8 and 10)
PC optimization, BIOS - acontis Developer Center
Configuring BIOS and POST
Select UEFI Boot Mode or Legacy BIOS Boot Mode (BIOS) - Oracle® X4 Series Servers Administration Guide
What does "Legacy USB Mouse" support in a BIOS mean? - Super User
Solved: not able to enable legacy boot (missing) - HP Support Community - 5862048
Can't get USB keyboard to work in pure DOS mode \ VOGONS
How to switch UEFI BIOS to Legacy BIOS on a PC
Enable Legacy Boot Mode
Select Legacy BIOS or UEFI BIOS Boot Mode - Oracle® Exadata Storage Server X6-2 High Capacity Service Manual
Moving your legacy-based PC into a legacy-free world How to configure your system to make best use of USB and IEEE-1394-based peripherals | Moving your legacy-based PC into a legacy-free world How
PC BIOS Settings - YouTube
Configuring Dell UEFI BIOS to Legacy mode to install Windows 7 - 404 Tech Support