models usually remain in production while there is demand, and you can buy secondhand versions online from websites such as eBay. Generally speaking, the newer the model, the faster its performance. Memory upgrades have made a difference, as well as the use of more powerful processors, as the Pi has evolved. There are plenty of uses for the Pi that don't need especially fast performance, though, so you might find that an older Pi is perfect for your project. The older models are described in this list:
❯❯ Raspberry Pi 1 Model B with 256MB memory: Although it’s called Model B, this was the first Raspberry Pi to be released, in February 2012. The Raspberry Pi Model B features an Ethernet connection for the Internet and two USB ports. It uses an SD card for storage.
❯❯ Raspberry Pi 1 Model B with 512MB memory: Released in October 2012, the Raspberry Pi Model B had twice the memory capacity. This improved the speed of some software, especially applications that used images heavily.
❯❯ Raspberry Pi 1 Model A: The Model A, released in February 2013, is a stripped-down version of the Model B. It has just one USB port and doesn’t have an Ethernet port for connecting to the Internet. It has 256MB of memory.
❯❯ Raspberry Pi 1 Model B+: The Model B+, released in July 2014, has been described by the Raspberry Pi Foundation as “the final evolution of the original Raspberry Pi.” It runs all the same software as the previous versions of the Raspberry Pi, but it has four USB ports, more GPIO pins for connecting electronics projects to the Pi, and lower power consumption and better audio than the Model B. In common with the Model B, it has 512MB of memory. Although all previous versions use SD cards for data storage, the Model B+ introduced the smaller MicroSD cards, which are now standard on the Raspberry Pi.
❯❯ Raspberry Pi 2 Model B: Launched in February 2015, this model doubled the memory on the Model B+ to 1GB. It increased performance, compared to the Model B+, while retaining its physical features. Over the years the Pi's performance has been improved through new software releases as well as updates to the hardware. The Pi 2 represents an immediately noticeable speed-up, compared to the Model B+.
In this book, we offer guidance on older models where possible but will assume you're using at least a Model B+ for the projects. For best performance, we recommend using a current model, if possible.
You’ll also see the Raspberry Pi Compute Module in the online stores alongside the Raspberry Pi, but this is something quite different. It’s aimed at engineers creating industrial applications (known as embedded systems) or products based on Raspberry Pi technology. We only mention it here in case you wonder what it is: It’s not covered further in this book, and it’s almost certainly not what you want to buy for your first Raspberry Pi.
Instead of running Windows or Mac OS, the Raspberry Pi uses an operating system called Linux. It’s a leading example of open source, a completely different philosophy to the commercial software industry. Rather than being created within the heavily guarded walls of a company, with its design treated as a trade secret, Linux is built by companies and expert volunteers working together. Anyone is free to inspect and modify the source code (a bit like the recipe) that makes it work. You don’t have to pay to use Linux, and you’re allowed to share it with other people, too.
You probably won’t be able to run the software you have on your other computers on your Raspberry Pi. It won’t run Windows or Mac software, and not all Linux software works on the Raspberry Pi. But a lot of Linux software that is compatible with the Raspberry Pi is available and is free of charge.
Figuring Out What You Can Do with a Raspberry Pi
The Raspberry Pi is a fully featured computer, and you can do almost anything with it that you can do with a desktop computer.
It has a graphical windows desktop to start and manage programs (see Chapter 4) as well as a shell for accepting text commands. (See Chapter 5.) You can use it for browsing the Internet (see Chapter 4), or for word processing and spreadsheets (see Chapter 6), or for editing photos. (See Chapter 7.) You can use it for playing back music or video (see Chapter 8) or for playing games. (See Chapter 19.) You can use the built-in software to write your own music, too. (See Chapter 14.) It’s the perfect tool for homework, but it’s also a useful computer for writing letters, managing your accounts, and paying bills online.
The Raspberry Pi is at its best, however, when it’s being used to learn how computers work, and how you can create your own programs or electronics projects using them. It comes with Scratch (see Chapter 9), which enables people of all ages to create their own animations and games while learning some of the core concepts of computer programming along the way.
It also comes with Python (see Chapter 11), a professional programming language used by YouTube, Google, and Industrial Light & Magic (the special effects gurus for the Star Wars films), among many others.
It has GPIO pins on it that you can use to connect up your own circuits to the Raspberry Pi, so you can use your Raspberry Pi to control other devices and to receive and interpret signals from them. In Part 5, we show you how to build some electronic projects controlled by the Raspberry Pi.
Getting Your Hands on a Raspberry Pi
One of the great things about the Raspberry Pi is that it's established a community of businesses that have created products for it, or have shared in its success by selling it. You can now buy the Raspberry Pi from a wide range of electronics companies for hobbyists. Global retailers include Pimoroni (www.pimoroni.com), The Pi Hut (https://thepihut.com), and Adafruit (www.adafruit.com). It's also available from the Raspberry Pi's distributors, RS Components (www.rs-components.com) and Element14 (www.element14.com).
You might also be able to buy it from your local computer or electronics store, although you'll probably find it's only available as part of a kit there. Shops often bundle the Raspberry Pi with other items you need to use it. It can be convenient to get everything at once, but it might not represent the cheapest way to get started.
Determining What Else You Need
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