EEPROM
The EEPROM is what contains the code used to initialize a computer when it is being booted. This data is stored as a plain byte array, and may mean different things to different CPU architectures. For example, for Lua it is usually a small script that searches for file systems with an init script, for other architectures it may be actual machine code.
EEPROMs can be programmed for specialized purposes, such as drones and microcontrollers.