Getting Your Raspberry Pi Up and Running - Raspberry Pi Hardware Projects - page 74

Filesystems
Computer storage like SD cards, USB memory sticks and hard disks essentially contain mil-
lions of separate compartments that store small (too small to even store most files) amounts
of data in large grids. The individual compartments, called blocks, are addressed by a coordi-
nate system - you can think of them as a piece of squared paper the size of a sports field. The
sports field is partitioned into areas that are handled by the operating system to provide file-
systems. It is the OS's job to manage how data is written to this massive storage area, so that
when a user refers to a file by name, all the tiny blocks of data are combined in the correct
order. There are different ways in which the blocks are formatted, with different features. As
such, an identical file will be stored differently on the underlying grid by different filesystems.
Typically, Microsoft Windows uses FAT or NTFS, OS X uses HFS Plus and Linux uses ext.
Most blank SD cards are formatted as FAT by default. Because the Raspberry Pi runs Linux,
it uses the ext filesystem, which must be set up and populated with files.
Transferring an Image Yourself
You need an SD card larger than 2GB to it the OS on it. A 4GB card is ideal.
Visit www.raspberrypi.org/downloads and follow the links to download the latest ver-
sion of Raspbian. You are looking for a filename containing the word raspbian and a date,
and that ends in .zip . Make a note of the letters and numbers that are shown as SHA-1
checksum. Because of the speed of development, new versions are released frequently, so the
exact name will differ from the one that's used in the following instructions. The location you
download the file to may also be slightly different, so you should use your location accord-
ingly when completing the instructions.
The download page has links to other distributions and other operating systems that you can
try later, but for now it's best to stick with Raspbian because it is reliable, has a good selec-
tion of software for beginners and is consistent with the examples in this topic.
The instructions for creating an SD card are different depending on which OS you're using.
Refer to the appropriate section for Windows, Linux and OS X.
Creating an SD Card with Windows
It is hard to check checksums in Windows, so the following instructions assume that the
downloaded image file is correct. After the download is complete, follow these steps to
uncompress it and transfer the data to the SD card:
1 Unzip the downloaded file 2012-10-28-wheezy-raspbian.zip .