In Raspberry Pi 4 microcomputers, the operating system is loaded by default from the micro-SD card, which is itself responsible for storing user files.
There is even the case of finding micro-SD units on the market with the official Raspberry Pi operating system (Raspberry Pi OS) preloaded from the factory, which guarantees immediate use of the microcomputer.
Booting Raspberry Pi 4 from a USB stick
However, there is another possibility of booting on Raspberry Pi 4: booting from a USB drive, for example a pen drive or external drive with a USB interface, as long as the operating system in question has been recorded on these drives.
In recently manufactured Raspberry Pi 4 boards, their firmware already contains the instructions to boot from a USB memory or SSD disk, and in those that are not capable of doing so, you only have to record the operating system again taking this detail into account.
In addition, the presence of two USB 3.0 ports ensures optimal speed of system operation.
How to check if your Raspberry Pi 4 Model B supports booting from USB
The best thing to do before wasting time burning a Raspberry Pi OS image to a USB thumb drive is to do a simple check from the microcomputer’s home screen.
To do this, turn off the Raspberry Pi 4 and remove the micro SD card. Power on the Raspberry Pi 4 again and verify on the boot screen that the bootloader version is later than March 2020. If so, your Raspberry Pi 4 supports booting from a USB drive.
And if the opposite is the case, you will have to run the Raspberry Pi Imager program to record on the micro-SD card a version of Raspberry Pi OS capable of writing the necessary update to the firmware of the microcomputer.
For this, open Raspberry Pi Imager from Windows and select the Misc Utility Images option. Next, select Bootloader and proceed to record the system on the micro-SD card. When you boot up your Raspberry Pi 4 it should already be able to boot from the USB ports.
How to prepare your USB stick to run Raspberry Pi OS
This procedure is no secret, as it involves the same steps as flashing the Raspberry Pi OS to a micro-SD card. The only recommendation is to have a USB 3.0 memory with a capacity greater than 32 GB. Check out the following article to learn more: