The Raspberry Pi celebrates its fourth birthday

The single-board Raspberry Pi came on the UK market about four years ago. At the time, its maker, Eben Upton, thought that around 10,000 of these little computers could be sold. In fact, more than eight million were sold in the 48 months following the first delivery, on February 29, 2012. In the meantime, the number of Rasp Pi owners has only grown [1]. This makes the small computer one of the most successful computers of all time.

Teaching Aid

In 2006, Upton became convinced of the need to teach young people programming skills. At the time he was finishing his PhD at the University of Cambridge and mentoring computer science prospective students. As a schoolboy in the 1980s, Upton had learned computer programming skills using the BBC Micro that was widely available in British schools at that time.

Once he started mentoring, Upton noticed huge gaps in knowledge among the students seeking admission to the Cambridge computer science department. Although they had basic knowledge in web design and HTML, they did not know how a computer functioned or how it looked on the inside. Also, the students were unable to handle either low-level assembly languages or higher-level programming languages.

Upton believed that the excellent academic standards of the Cambridge computer science major could only be preserved if students had more knowledge and experience in computer science. It took three years of work with other concerned colleagues before the Raspberry Pi Foundation came into being. As stated in its incorporation documents, the primary purpose of the foundation is to impart programming skills and additional capabilities for the field of information technology.

From the beginning, it was clear to Upton and his colleagues that theoretical knowledge would not suffice. Information technology needed to be made appealing to young people. Upton hit upon the idea of a small computer that would be similar to the home computers of the 1980s and the early 1990s. He thought students would be interested in tinkering with the devices.

Thus, the device had to be small, efficient, robust, and easily affordable. The group around Upton also recognized the importance of multimedia capabilities in the hardware. Young people had become accustomed to online multimedia content and would reject a computer that existed merely to be programmed on a console.

At the Wrong Time

Upton and his colleagues worked on developing prototypes from 2006 to 2008. Unfortunately, the protypes all failed during testing. Some were not powerful enough; others had a price tag high enough to drive away many teenagers. In spite of these early setbacks, Upton created the non-profit Raspberry Pi Foundation. The founders included David Braben, from the computer manufacturer Frontier Developments; Jack Lang, a business angel and former Acorn colleague; Pete Lomas, from component manufacturer Norcott Technologies; and Robert Mullins and Alan Mycroft, both from the University of Cambridge.

In 2011, when Upton was employeed by the chip manufacturer Broadcom, he finally made a breakthrough in the development. Broadcom was introducing the chipset BCM2835 for use with smartphones. This chip set was extraordinarily compact in size, while offering the required performance potential to serve as the basis for a small computer. The BCM2835 became the heart of the Rasp Pi Models A, B, B+, Zero, and the Compute module.

The Foundation developed a prototype of the future small computer based on the BCM2835. About the same size as a credit card, the prototype came with all of the necessary connections. The prototype was made possible because of the highly integrated construction technique of the BCM2835. The system on a chip (SoC) contained its own CPU taken from the ARMv6 family, as well as all of the peripherals. This meant that an entire computer could be built from this one chip along with a few other components. The $35 price reflected the simplicity.

The GPIO (General Purpose Input/Output) header is the central element of the single-board computer. These inputs and outputs can be programmed as desired. They let the Rasp Pi control external components from which the Pi can receive signals for internal processing. The GPIO header makes it possible to come up with completely new applications for the little computer in addition to the multimedia and general use for school children.

The foundation arranged for production of 50 prototypes and tested them with various operating systems and desktop environments. It became apparent that the hardware could handle a mature interface like LXDE under Debian Squeeze, which later became Wheezy. Thanks to the implemented GPU, it was even possible to view videos in 1080p resolution without any stuttering. With the success of these tests, the small computer went into production after slight modifications.