The new Pi appears to be a considerably tastier prospect...
The launch of the Raspberry Pi back in 2012 was something of a phenomenon. The first batch produced sold out in minutes, with demand crashing the website of manufacturer Farnell and retailer RS Components despite the early-morning launch schedule. Since then, the project - founded with the aim of producing low-cost computing hardware for educational and experimental uses - has gone from strength to strength, with the Raspberry Pi Foundation claiming world-wide sales of 4.5 million to date.
In the years since launch, the Foundation has released cut-down variants, models with more efficient power circuitry and enlarged interface capabilities, and even an ultra-compact version designed for industrial use. Each of these, however, used the Broadcom BCM2835 processor of the original launch model. Designed for use in set-top boxes and long-outdated even in 2012, the BCM2835's single-core 700MHz processor and ageing ARMv6 microarchitecture have long been a thorn in the side of anyone trying to use a Pi for CPU-bound tasks.
That's where the Raspberry Pi 2 enters the picture. Launched this week in Model В variant, with a Model A (lacking all but one USB port and without on-board networking) planned for the future, the Raspberry Pi 2 is the first outing for Broadcom's new BCM2836 system-on-chip design. Built specifically to power the next-generation Pi, the BCM2836 ups the clock speed to 900MHz from 700MHz, packs four individual processing cores where the original had but one, and uses the newer ARMv7 micro-architecture. In short, it's a not-inconsiderable upgrade.
The launch couldn't have come at a better time. While the Pi launched into a market where rival development boards cost anything up to ten times the £30 launch price, alternatives appeared thick and fast once the Pi had proven a success. Many of these cost the same as the Pi, or slightly more, yet offer more advanced hardware such as dual- or quad-core processors, high-speed SATA storage connectivity, or USB 3.0 ports. Had the Foundation stuck with the BCM2835, the Pi risked obsolescence despite an enthusiastic community of fans.
If you're not paying attention, it'd be easy to mix the Raspberry Pi 2 in with its predecessor. While the launch of the Raspberry Pi Model B+ (a naming convention borrowed from Acorn's BBC Micro family) brought with it a revised board design with enlarged 40-pin general-purpose input-output (GPIO) header, the Raspberry Pi 2 is largely unchanged. The biggest difference, silk-screened labelling aside, is a shift away from the package-on-package (PoP) format that saw the SoC and RAM sandwiched together on the top side of the board; instead, the Raspberry Pi 2 places the new SoC on the top, while the enlarged 1GB RAM module is slung on the underside of the board.
That change aside, however, the new Raspberry Pi 2 will be immediately familiar to anyone who has used its predecessor. The 40-pin GPIO header, used to interface with external hardware including add-on boards dubbed HATs, is still in-place and offers full compatibility with existing accessories. Unfortunately, this also means there have been no improvements on that front: there's still no analogue-to-digital (A2D) or pulse-width modulation (PWM) capability built in to the board, meaning more advanced hardware interaction will still require the use of an external device.
The Raspberry Pi 2 launch isn't about dramatic redesigns, though. That becomes immediately obvious by looking closer at the software. The ARMv7 micro-architecture of the new chip is backwards-compatible with the ARMv6 original, and the stock Raspbian Linux operating system boots happily on either device with no changes aside from an ARMv7-compatible kernel image already present in the latest release.
Everything else runs without recompilation, and at a considerably improved speed. The new micro-architecture brings with it the promise of wider compatibility with other software packages, too: Canonical's Ubuntu is now supported on the Raspberry Pi 2 in the form of its Snappy Core variant, marking the first Ubuntu release for the platform, while Microsoft has - to the surprise of everyone - announced that it will release a version of Windows 10 for the board later this year completely free of charge.
Even without these new operating systems and the possibilities they bring, the Raspberry Pi 2 proves a tempting upgrade. The Raspberry Pi Foundation claims that the new version is six times faster than its predecessors, and benchmark testing bears that out: using the SysBench CPU test the new model actually came out 6.7 times faster, while a compression test using the multi-threaded PigZ package showed a sevenfold performance boost. For multi-tasking, especially at the desktop, this translates into a far smoother experience with none of the delays and hitching suffered by earlier models. Power draw is the trade-off, measured at nearly double that of a Raspberry Pi Model B+ - but, interestingly, only slightly higher than the original Raspberry Pi Model B.
Not everything will be faster, of course. The Ethernet port, which will be removed from the Raspberry Pi 2 Model A when it launches later this year as a means of cutting costs, remains a 10/100 model connected to the system via a single shared USB channel. While it's fast enough in benchmarking, measuring at the same 89Mb/s throughput as earlier Raspberry Pi models, using the Ethernet port at the same time as one or more of the four USB 2.0 ports results in a considerable reduction in throughput. The USB ports themselves are also still limited to 1.2A total power output, far below the 2A a standards-compliant USB 2.0 implementation should really offer.
These niggles, present in previous releases and uncorrected in the Raspberry Pi 2, are undeniably annoying but far from a deal-breaker. The Pi's low price, launching at £30 and only dropping since, made it the go-to board for education despite its drawbacks; the new Raspberry Pi 2, despite its massively improved processor and doubled memory, launches at the same attention-grabbing price - something that its competitors, without the Foundation's close ties to chip-maker Broadcom, will struggle to beat. Gareth Halfacree
Evolution rather than revolution, but a handy upgrade nonetheless.