The A388 System-On-Module used by Helios4 provides an **32 Mbit SPI NOR flash** connected to SPI bus 1, Chip Select 0 ([Winbond W25Q32BV Datasheet](https://media.digikey.com/pdf/Data%20Sheets/Winbond%20PDFs/W25Q32BV.pdf)).
By default, Helios4 is configured to boot from microSD card. To boot from SPI NOR flash (after [writing U-Boot into SPI NOR flash](#write-u-boot-to-spi-nor-flash)), please change Boot Mode on DIP Switch **SW1** to:
*A prebuilt SPI image of U-Boot for Armbian OS can be downloaded from [here (version 2013.01)](/files/uboot/u-boot-armbian-2013.01-spi.bin) or from [here (version 2018.11)](/files/uboot/u-boot-armbian-2018.11-spi.bin).*
Concurrent access on SPI NOR and SATA drives can lead to unstable SATA. The following instructions has taken this issue into consideration and workaround it by disabling the SATA temporary.
6) If you want to take the opportunity to move your RootFS to another device, jump to this [section](#moving-rootfs-to-other-device). Otherwise you may disable spi_workaround in /boot/armbianEnv.txt
You will need to access to Helios4 via Serial Console. Please refer to [Install](/install/#step-4-connect-to-helios4-serial-console) page for instructions.
1) Upload the U-Boot SPI binary that you built to Helios4 and rename it as **u-boot-spi.bin**.
2) Download boot_spi_en.scr from [here](/files/uboot/boot_spi_en.scr) and put it to /boot/.
Prebuilt SPI images for Armbian are configured to automatically run /boot/boot.scr on microSD or USB drive. There is no need to set up u-boot environment to boot Armbian.
Add U-Boot ENV variables to prevent U-Boot to relocate fdt and initrd into RAM address that is not accessible by kernel, and set the correct device tree name for Helios4 board
Now you have the option to move your Root FileSystem to a storage device connected to USB3.0. Under Armbian you can use the **nand-sata-install** utility to easily take care of this procedure.
Only the USB **top port** is supported by U-Boot 2013. So you need to plug the storage device on which you want to move the RootFS in the top port. In U-Boot 2018 both USB ports are supported.