The Raspberry Pi uses a configuration file instead of the BIOS you would expect to find on a conventional PC. The system configuration parameters, which would traditionally be edited and stored using a BIOS, are stored instead in an optional text file named config.txt. This is read by the GPU before the ARM CPU and Linux are initialised. It must therefore be located on the first (boot) partition of your SD card, alongside bootcode.bin and start.elf. This file is normally accessible as /boot/config.txt from Linux, and must be edited as root. From Windows or OS X it is visible as a file in the only accessible part of the card. If you need to apply some of the config settings below, but you don't have a config.txt on your boot partition yet, simply create it as a new text file.

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