The Raspberry Pi celebrates its fourth birthday

The Family Has Grown

The original Rasp Pi was quickly improved. In fact, a number of new models have been released during the past four years. The first Rasp Pi 1 (RPi1) Model B was followed barely a year later by the slimmed-down RPi1 Model A. It used the same CPU and GPU as the Model B, but it offered 256MB instead of 512MB of RAM and one USB port instead of two. Moreover, it did not have a LAN connection. The advantage to this model was that it cost $25 instead of $35 for the Model B.

Some six months later, in April 2014, the Rasp Pi Compute module became available (Figure 1). This special variation of the Model B/B+ with 4GB of eMMC storage was designed as a DDR2 SODIMM storage module. It did not have any connections for peripheral devices.

Figure 1: The Compute module (on the left) is much smaller than the first Rasp Pi (on the right).

This product was aimed at the industrial applications market. With its standardized SODIMM connection, the module is easily integrated via corresponding plugins, which are part of industrial systems [7]. The modules were sold in quantities of 100 at $30 each. A developer kit included an appropriate I/O board with all the necessary connections. This board also ensured that power was supplied to the module.

Just three months later in July 2014, the Raspberry Pi Foundation brought the Model B+ on the market. Unlike its predecessor, it had four USB jacks and a micro SDHC card slot for bulk storage instead of the previously used SDHC mini jack [8], and it had 40 GPIO pins (Figure 2). At first, the Model B+ cost $35 – the same price as the older model, which was still being sold.

Figure 2: The first-generation Model B+ with its four USB ports looks a lot like the current Rasp Pis. © Raspberry Pi Foundation

A short time later in November 2014, the Foundation presented yet another model. This was the A+. The A+ distinguished itself from the earlier Model A with the introduction of the SDHC micro jack and an expanded GPIO header with 40 pins. In this unit, power consumption was lower due to the use of smaller components, and the price was reduced from $25 for the Model A to $20 for the Model A+ [9].

On February 2, 2015, Upton announced that the Rasp Pi 2 (RPi2) Model B was ready for sale [10]. This new system stood for genuine progress. Priced like the first-generation Model B+ at $35, it had a replacement for the aging BCM2835 chipset in the form of the BCM2836 SoC running at 900MHz. Until the release of the second-generation Model B, all of the Rasp Pis were constructed with the BCM2835, which worked at a clock rate of 700MHz.

Moreover, the BCM2836 had a quad-core instead of a single-core CPU and 1GB of RAM. The GPU, audio hardware, and the SDHC micro jack remained unchanged in the new chip, as well as the overall dimensions. Even so, the power requirements increased from 3 to 4 watts.

Due to its quad-core processor, the increase in RAM, and the underlying ARM Cortex A7 architecture, the new Raspberry computer had far greater performance capabilities. Even customary Linux Desktop distributions ran smoothly on this Rasp Pi. As a result, more and more projects have ported their systems to the ARM Cortex architecture. Meanwhile, there are a considerable number of distributions available. In mid-May of 2015, the price for the RPi1 Model B+, which was still in production, was lowered to $25.

On November 26, 2015, Upton announced the immediate release of the Rasp Pi Zero [11]. This new Pi marked a complete break with its predecessors. Its size was greatly reduced, and it was powered again by the BCM2835 SoC, but it sported a stunning $5 price tag (Figure 3). Unlike its larger siblings, this Rasp Pi got rid of connectors. The connector for the camera module, which had been specially developed for the Rasp Pi, the LAN connector, and the plug for audio devices were all gone. Moreover, the board had just a single micro USB connection instead of the typical USB 2.0 jacks. No changes were made to the working memory and the GPU. At 1GHz, the CPU even ran a little bit faster on the Zero than on the RPi1 Model B+.

Figure 3: The Rasp Pi Zero also counts among the ranks of complete computers. The trimmed-down module is targeted mostly at industrial users. © Raspberry Pi Foundation

Eben Upton explained that the motivation for this extremely economical single-board computer was to provide users who couldn't afford other models with an opportunity to learn programming. This target group appears to be larger than previously known. The Rasp Pi Zero experienced delivery delays because of the extraordinary demand and was out of stock shortly after being announced (see the "Rants and Raves: Zero Zero" box).

Rants and Raves: Zero Zero

Have you managed to grab a Pi Zero? If so, then it probably comes directly from the UK. In Germany, it has become impossible to buy one of the $5 Pis. Dealers and large distributors like Farnell element 14 have already removed the Pi Zero from their line of goods.

Even in the birthplace of the Rasp Pi, this little computer is very difficult to get. Usually, it is only available for a few days after an announcement, and then you can only purchase one of them. Additionally, a veritable black market has sprung up, where the Pi Zero is offered for inflated prices – up to $52.

The delivery problems most likely result from the Raspberry Pi Foundation arranging for the Pi Zero to be produced in small batches. The larger Rasp Pis are produced in huge numbers by established companies like RS Components and Farnell. Given the restrictions on production numbers, these companies have declined to get involved with the low-priced Pi Zero because the margins are too small. Insiders complain that the Foundation announced the Pi Zero just to deflect attention from other economical single-board computers like the "$9 computer" CHIP. They had no intention of actually earning money with the tiny device. There are rumblings that each of the Pi Zeros actually cuts into company profits.

In reality, things probably are not that bad. Upton made an announcement in mid-February about attempts to stabilize the production level of the Pi Zero at 50,000 units per month. He reported that he had just issued two orders for a total of 150,000 Pi Zeroes. Nonetheless, the RPi3 continues to be considered a top priority. Thus, it is entirely possible that availability issues will stick around for the Zero.

The latest flagship product for the Raspberry Pi Foundation is the RPi3 Model B, which was released on February 29, 2016 [12]. It has the same dimensions, connections, and $35 price tag as its predecessor. However, the new model comes with a BCM2837 chip set, which contains an ARMv8 quad-core processor (Figure 4).

Figure 4: The RPi2 above and the brand-new RPi3 below appear identical.

This means that the RPi3 is the first member of the Pi family to be able to work with a 64-bit operating system. Additionally, the CPU clock rate has increased to 1.2GHz. It also has modern WiFi capability that uses the 802.11b/g/n standard, and it comes with Bluetooth+4.1 and Bluetooth Low Energy. In spite of the new interfaces and the increased clock rate for the CPU and GPU, the new model does not consume any more power than previous models.

Like the older models, the RPi3 is downward compatible. This ensures that projects developed for the RPi1 or RPi2 work without problems with the newest member of the family. Because it can run 64-bit operating systems, it's likely more alternative system software will appear in the medium term than already has for its predecessors.

A veritable Raspberry ecosystem has sprung up, where accessories of all kinds are developed and sold. The offerings include – among other things – covers for the otherwise naked computer, peripheral devices like WiFi sticks, and power supplies. The commercial counterpart to the Foundation has been quick to put licensing agreements in place with third-party manufacturers (Figure 5).

Figure 5: The distributors RS Components and Farnell plus other license holders offer numerous accessories for each version of the Rasp Pi.


Upton has undoubtedly achieved his goal of helping students in British public schools become interested in computer science and fostering the spirit of discovery. About a third of the little computers produced are sold domestically.

The Rasp Pi has quickly gained fans in the rest of the world, too. In Africa, for example, it's popular because it can be used with a television via its HDMI connector. Additionally, an active scene of Rasp Pi enthusiasts, geeks, and makers has formed around the little computer. Users have put together everything from media centers to drones to 3D print controls to a WiFi grill thermometer.

Industry is starting to see the possibilities offered by the Rasp Pi. Increasingly, it serves in various versions as a control computer in industrial settings, and it plays an important role for the Internet of Things (IoT). The new RPi3 should provide an additional boost, especially with its ability to handle compute-intensive tasks. The high performance CPU will be able to complete tasks that previous models could not assume.

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