Eben Upton, designer of the Raspberry Pi, noticed the slide in skill levels when he was working at Cambridge University’s Computer Laboratory in2006. Students applying to study computer science started to have less expe-rience of programming than students of the past did. Upton and his university colleagues hatched the idea of creating a computer that would come withall the tools needed to program it, and would sell for a target price of $25. It had to be able to do other interesting things too so that people were drawn to use it, and had to be robust enough to survive being pushed in and out of school bags hundreds of times.
There are two versions of the Raspberry Pi: the Model B (which was released first) and the Model A. The differences between the two are that the Model B has two USB sockets (whereas the Model A only has one), the Model B has an Ethernet socket, and editions of the Model B released after October 2012 contain twice the memory (512MB, compared to 256MB on the Model A and the first batches of the Model B). The Model A sells for $25, whereas the Model B sells for around $35.
The Raspberry Pi was made possible in part by the advances in mobile com-puter chips that have happened in recent years. At its heart is a Broadcom BCM2835 chip that contains an ARM central processing unit (CPU) and a Videocore 4 graphics processing unit (GPU). The CPU and GPU share the memory between them. The GPU is powerful enough to be able to handle Blu-ray quality video playback. Instead of running Windows or Mac OS, the Raspberry Pi uses an operating system called Linux.
...You don’t have to pay to use Linux, and you’reallowed to share it with other people too. Unless you already use Linux, you won’t be able to run the software youhave on your other computers on your Raspberry Pi, but a lot of software for Linux is free of charge.
...It has a General Purpose Input/Output (GPIO) port 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 V, we show you how to build some electronic games controlled by the Raspberry Pi.
For something that costs so little, the Raspberry Pi is amazingly powerful,but it does have some limitations. Although you probably use it as a desktop computer, its power is closer to a mobile device (like a tablet) than a modern desktop PC. By way of example, the Raspberry Pi Foundation says the Pi’s overall performance is comparable with a PC using a 300 MHz Pentium 2 processor, which you might have bought in the mid to late nineties, except that the Raspberry Pi has much better graphics. The memory of the Raspberry Pi is more limited than you’re probably used to, with just 512MB or 256MB available. You can’t expand that with extra memory in the way you can a desktop PC. The graphics capabilities lag behind today’s market somewhat too: The Raspberry Pi Foundation says the Pi’s graphics are roughly the same as the original Xbox games console, which was released 10 years ago.