Getting the Operating System

So, the first thing we need to do is download and install the Raspberry Pi’s operating system. For general purpose and/or NAS/fileserver usage you want to install the Raspbian distribution. If you are fairly new to computers, don’t worry too much about the terminology, you’ll get the hang of it. Plus, people (especially marketing people) misuse the terms so much that you can interchange things a lot anyway and no one is going to mind.

Now then, if you’re going to install an operating system, it is probably useful to know what one is. An operating system is a collection of computer software that is responsible for the basic functionality of a computer. It includes a kernel (which manages the computer’s resources and allows other programs to access them), device drivers (which allow the kernel to talk to the various bits of the computer, like your keyboard and mouse) and basic system libraries and applications that allow for things like reading and writing files. An operating system bundled together with a useful selection of more high level applications (such as word processors etc.) is known as a distribution.

There are various ways to install a distribution, we are going to use an image file. An image is a copy of a disk, in this case, one which has our operating system and some useful applications from our distribution already installed on it. The image is installed by simply writing it directly to disk (in this case, your SD card.) Be aware that this isn’t the same as copying the image file to a disk, the difference will (hopefully) become clear latter on. Anyway, using an image file will give you a working computer without having to deal with tricky install issues, like how do you install programs on your computer when one of the programs you need to install is the program that installs programs!

So a quick recap.

Kernel
does all the very basic stuff, like accessing the processor.
Device drivers
software that enables the kernel to talk to the hardware in your computer.
Applications
programs that do stuff, can be simple or really massively complicated.
Libraries
collections of useful application fragments so that each application doesn’t have to duplicate the same code.
Operating System
kernel plus device drivers plus basic system applications and libraries (there is no consensus about what constitutes a basic application).
Distribution
operating system plus collection of high level applications.
Image
a copy of a disk that can be copied to another disk. In this case, our image is of a disk that has the Raspberry Pi’s operating system installed on it.

Now you’ve got that clear, I’ll add a bit confusion back: Microsoft’s well known Windows software started life as an operating system (called DOS) but has grown into what would be better described as a distribution yet is still commonly referred to as an operating system.

As for the Pi, it uses the Linux kernel, and the GNU basic system applications, commonly known as GNU/Linux or just Linux. Linux is packaged with user level applications for the pi by a few distributions: Raspbian, Arch Linux and Android, to name a few. Of the different distributions, there are a few different images you can get, which have different default setups, but don’t worry about them for now. Just go get the default Raspbian Image from www.raspberrypi.org/downloads (using your Ubuntu computer).

At the time of writing, the current version is 2012-12-16-wheezy, but get what ever is the latest version. Use BitTorrent if possible. BitTorrent is a clever way of sharing the downloading of data between the people downloading it (typically servers have problems when new software etc. comes out, as suddenly lots of people try download it at the same time, putting huge demands on the server. With BitTorent, the more people who download something, the more people there are to download it from, so it actually gets quicker to download something the more people that download it!)

Note that when you click on the torrent file on rasperrypi.org, you need to select open rather than save. The torrent file isn’t the image, it is a file that tells the BitTorrent client where to download the image from.

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