system
Given the following post, respond as if you're commenting on Reddit:
human
How do they load operating systems onto completely blank computers?

Say I have a computer that is just the absolutely bare electronics. Nothing to read a usb or any inputs. How would I load an operating system onto it? How do computer manufacturers accomplish this?
gpt
The motherboard of a computer is equipped with something called UEFI (Unified Extensible Firmware Interface), the successor of the BIOS (Basic Input/Output System). The UEFI handles the first steps of starting a computer. It contains enough logic to manage storage devices (HDDs, SSDs and USB storage), input devices (keyboard, mouse) and display output. The UEFI software is stored on a dedicated chip on the motherboard, which is preloaded by the manufacturer.

When the system starts, the UEFI will check its settings to determine which devices to search for operating systems and it will hand over the reins to the first operating system it finds in the boot order. In this context, a USB stick with an OS installer also counts as an operating system that can be started. Once started, this OS will handle the process of copying the files from the installation media to the permanent storage location (typically from USB to SSD).