Raspberry Pi A, User Manual, Page: 124 / 314

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P A R T I
C O N N E C T I N G T H E B O A R D
OWING TO ITS origins in embedded computing, the BCM2835 chip at the heart of the
Raspberry Pi doesn’t have anything like a PC’s Basic Input-Output System (BIOS) menu where
various low-level system settings can be configured. Instead, it relies on text files containing
configuration strings that are loaded by the chip when the power is switched on.
Before taking a look at the various options available in these files—
config.txt
and
cmd-
line.txt
—a word of warning: changing some of these settings away from their defaults
can result in a Pi that doesn’t boot until the files are reverted, in the best case, and can
physically damage the system, in the worst case. These potentially dangerous settings will be
highlighted with warnings in this chapter.
TIP
If you’re using the Raspbian distribution, the easiest way of changing the majority of settings
is to use the
raspi-config
utility (see Chapter 6, “The Raspberry Pi Software Configuration
Tool”). These instructions are provided for those on other distributions or who would prefer to
do things manually.
Editing Configuration Files via NOOBS
If you have edited your configuration files in such a way that your operating system no lon-
ger boots, the easiest way to restore them is to use the NOOBS software (see Chapter 2,
“Getting Started with the Raspberry Pi”). If your operating system was installed via NOOBS,
you can use the tool to edit the configuration files; if you installed your operating system
manually, you will need to remove the SD card and use a second computer to edit the files.
To load NOOBS after you have used it to install your operating system, hold down the Shift
key as you apply power to the Pi. This will bypass the loading of the operating system and
instead boot into NOOBS, but with a new option: the Edit Config button at the top of the
menu (see Figure 7-1).
Clicking the Edit Config button (or pressing the E key) will load a text editor window with the
two configuration files—
config.txt
and
cmdline.txt
—pre-loaded (see Figure 7-2). You
can make changes as described in this chapter in the text editor with your keyboard and mouse,
and click the OK button at the bottom-right to save your changes to the SD card. When you’ve
finished making changes, click Exit on the main window to reboot the Pi with its new settings.
TIP
If you have a Raspberry Pi Model B that is connected to the Internet, you can also click the
Online Help button or press the H key on the keyboard to load a web browser that will take
you to the Raspberry Pi Forums. This is an invaluable resource if your Pi isn’t working properly,
allowing you to find help or post a question to get your Pi computing back on track.