How to Update the BIOS in Legacy Mode

Some POS terminals require BIOS updates through Legacy Mode. Sunany provides this guide to help users create a DOS bootable USB drive and complete the BIOS update process using the Legacy boot method. Before starting, please prepare the required tools and BIOS files, and follow the instructions carefully to ensure a successful update.

Required Tools
download:  Rufus-3.18

Watch the video below for a complete demonstration of updating the BIOS in Legacy Mode.

BIOS Update Steps

Before you begin, prepare a USB flash drive with a capacity of at least 8GB.

Insert the USB drive into your computer and launch Rufus-3.18.

Select your USB drive under Devi ce.

Under Boot Selection, choose FreeDOS.

Keep the File System as the default Large FAT32, then click START to create a bootable DOS USB drive.

After the process is complete, copy the BIOS files to the root directory of the USB drive.

Connect a keyboard to the POS terminal that requires the BIOS update, and insert the USB drive directly into one of the motherboard’s native USB ports. For better compatibility, avoid using USB hubs or expansion ports.

Power on the POS terminal, then immediately press F7 or F11 repeatedly to enter the Boot Menu.

Select your USB drive and make sure to choose the Legacy option, not the UEFI option.

After entering the DOS screen, press 1, then press Enter to start the BIOS update.

Wait until the progress reaches 100%. When you see “FPT Operation Passed”, the BIOS update is complete.

Remove the USB drive, press the power button to shut down the terminal, and then turn it on again.

During the first startup, the system may restart two or three times. This is normal. Please wait until the boot process is complete.

Important: Do not operate the POS terminal or interrupt the BIOS update during the flashing process. Any interruption may cause permanent firmware damage.