So-called "maker culture" has become increasingly in vogue, and even championed by sci-fi author Bruce Sterling. While the general public loves devices made by Apple that you can only customise within very strict boundaries, there's still a huge number who want to tinker and try out the possibilities. For those of us in the second camp, nothing could be more exciting than the Raspberry Pi. Created by a group with its roots in the Cambridge University Computer Lab, the Pi is an almost complete computer, but packed into a single circuit around the size of a credit card, and costing a mere $35, or $25 for a cut-down version. We took a look at the more expensive $35 Model B.
The Raspberry Pi is not quite as general-purpose as an Arduino, the Open Source controller board that powers so many guerrilla gadget projects. But on the other hand it's also easier for the average person to set up. The Model B comes with virtually everything an average computing device might need, and an amazing amount of connectivity considering its size. A Broadcom "system on a chip" combines a 700MHz ARM 11 processor, Broadcom VideoCore IV GPU and 256MB of RAM into one tiny piece of silicon. There are two USB ports, 10/100 Ethernet, HDMI and composite RCA video out, an audio minijack, and an SD Card reader. The Model A merely loses a USB and the Ethernet port, but drops from 3.5W to 2.5W power consumption, so is even better suited to embedded applications than the Model B.
What you don't get is any form of power source, non-volatile storage, nor chassis. Power comes in via a standard 5V micro USB connection, so any mobile phone charger would do. We’re starting to see a range of third-party chassis options, but many of these are made to order using 3D printers aimed at rapid prototyping rather than manufacture, and we're not enormously convinced by the majority of them. The one we opted for ourselves was from ModMyPi (www.modmypi.com), which comes in a range of colour options, but ours hadn't arrived at the time of writing. Part of the fun of the Pi, however, is what you build it into. Got an old toy you would like to become your new computer? If the Pi fits, all it takes is a little handiwork and ingenuity to make a pretty novel computing device.
The storage options are relatively limited, though. There's no SATA or PATA connection for attaching a hard disk. You will most definitely need to add a SD card, as this will be where the operating system loads from, although you can also add a USB hard disk which the SD loader points to for the majority of the OS files. But there's no rule as to what you must run on this hardware. This is where things start to get interesting, and the true magic of the Pi emerges.
There are currently three official Raspberry Pi Linux distributions for varying levels of expertise, including one aimed at embedded applications. However, we loaded the experimental Raspberry Pi Fedora Remix onto ours, as this distribution includes a lot of useful software. Loading an operating system involves using an image writing application to copy across the distribution to the SD card via another system. You then install the card into the Raspberry Pi and power it up, with monitor, keyboard, mouse and networking attached, to complete the setup routines.
The other piece of the Pi that promises exciting customisation options is the 26-pin GPIO header. This can be used to enable the Pi to control or receive input from a variety of external peripherals, including LEDs and switches, or any other supplementary circuitry that requires input or output within the appropriate voltage range, for which details can be found on the Raspberry Pi website. You can then program the Pi's software to control and react to these pins. An enthusiast community has already built up around this aspect of the Pi, and this is a large part of what the device was meant to do. Its low price makes it ideal as the controller for a variety of devices, using well documented Linux-based programming environments. There's a DSI connector as well, for attaching Raw LCD panels, and a CSI MIPI camera interface, although at present there is no software support for either of these.
However, even if you don't want to plumb the depths of electronic device control possibilities offered by the Raspberry Pi's GPIO, the device on its own can still make a handy and extremely cheap computer, with a host of uses. You could make it a simple Web terminal, or use it for general office tasks with some Open Source software. The Fedora Remix distribution we were using contained AbiWord word processing, Gnumeric spreadsheet and GIMP image editing apps, as well as Firefox 3.6, so could be used for general everyday office work straight away, although it's a little sluggish if you're used to a recent PC or Mac. And, of course, there's a wealth of packages available for install - or you can program your own. It could be a simple network video player to attach to a TV. Development work on a special Raspberry Pi version of media centre environment XBMC called Raspbmc is currently under development, and reached beta release in May 2012.
It's worth mentioning, however, that the Raspberry Pi is not a very quick computer. Its 700MHz ARM 11 is around half as fast as some current mobile phones. Versions of the sixth-generation ARM 11 powered the original iPhone and iPhone 3G, HTC Wildfire, Kindle 2 and Nokia N8. But ARM is now on its seventh-generation Cortex models, and support for this older sixth generation has been removed from some Linux distributions, in particular Ubuntu. Nevertheless, it's still up to some pretty useful tasks. The VideoCore GPU supports hardware encoding and decoding of 1080p video as well as OpenGL ES 2.0 and hardware-accelerated Open VG. Raspberry Pi describes the overall performance as a Pentium II 300 with Xbox 1 graphics.
The Raspberry Pi is a unique, revolutionary device, and as such there really is nothing on the market to compare it with. Even the cheapest desktop is both larger and more expensive, although obviously quite a bit more powerful. Yes, the Raspberry Pi has limited processing capability, but its low price and tiny size make it unbelievably flexible for tinkering. If you break it, replacement won't exactly be expensive. It's another great British computing innovation, carrying on the tradition of the BBC Micros that its Model A and B names refer to.
Note: Since launch, the Raspberry Pi is now priced in dollars, which the company explains as being because the component parts are priced in dollars. So the price in Sterling will vary with the current exchange rate.