> Where does the rpi4 store the firmware necessary to read from the sd card where this software is (presumably) stored? The main chip of the RPi4 has a small a

> Where does the rpi4 store the firmware necessary to read from the sd card where this software is (presumably) stored? The main chip of the RPi4 has a small amount of code in a built-in ROM which runs on boot. In the normal boot flow, that code loads the bootloader from the EEPROM chip, but it can also read a recovery image from the SD card. See https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#raspberry-pi-4-boot-flow https://www.raspberrypi.com/documentation/computers/raspberr... for details (or https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#boot-sequence https://www.raspberrypi.com/documentation/computers/raspberr... for how it was on the older RPi devices).