ARM Cortex CPU

Featured Editorial: The ARM Processor and How It Became the Powerhouse It Is Today

May 28, 2012 - Written By Tom Dawson

In the last four to five years we’ve seen mobile phones move to smartphones, we’ve seen the introduction of tablets – both mobile platforms that allows to get a little work done and enjoy content in ways never before possible. Something that’s always been of some interest to myself is that this was all made possible by not the giant Intel that for so long now has been on top making desktop and laptop computers more and more powerful but processor designs from a small company founded in Cambridge, England. ARM Ltd.

How Did This “ARM” Get Started, Anyway?

ARM itself – as a computing architecture – was born out of necessity. Acorn Computers had achieved some success with the BBC Micro line of computers, a line of computers that were used in schools here in the UK for years and in great many numbers. However, for Acorn to come close to achieving success in the emerging business PC market they would need more power than the MOS Technology 6502 from the BBC Micro could muster. As such, Acorn Computers came to the conclusion that they would need a new architecture altogether. Engineers at the company started to research how they would go about designing their own processor, as they did this they came across papers from the Berkeley RISC project, after realising the potential of said project had persuaded them that if a class of grad students could get so close, they would have no problem. Acorn Engineers Sophie Wilson and Steve Furber got down to creating the processor, after successful simulations had shown that massive R&D and state-of-the-art technology were not needed to produce something like this, they approached the company’s CEO, Herrman Hauser, who gave the go-ahead for the project A small team was put together to work on the design that Wilson had created. VLS Technology had been chosen to produce the chip – having supplied Acorn with chips in the past.

The first ARM processor, dubbed unceremoniously the ARM1 was produced two years after the Acorn RISC Machine project was founded 1983. However, the first units put into production were the ARM2. This processor featured a 32-bit data bus, 26-bit address bus an 27 32-bit registers. Due to the program counter being limited to 24-bits, program code had to lie in the first 64MB of memory. The humble ARM2 had a transistor count of only 30,000 compared to the 68,000 transistors in the Motorola 68000, The ARM2 used less power and still ran faster than the Intel 80286.

What Happened With This New Stuff Then?

Towards the end of 1980s, Apple and VLSI Technology began working with Acorn on newer, more powerful – yet still power efficient – versions of the ARM core. This work was deemed important enough to spawn a new company dubbed Advanced RISC Machines, this company then became ARM Ltd as its parent company ARM Holdings floated on the London Stock Exchange and the NASDAQ in 1998. This partnership between Apple and ARM led to the new ARM 610 CPU, which Apple would go on to use in their Newton PDA. With relative success now in ARM’s favor, it was unsurprising to see interest from the rest of the tech world. DEC – of VAX fame, sold to Compaq in 1998 and subsequently acquired by our friends at HP in 2002 – licensed the ARM6 Architecture and produced it’s super power efficient range of StrongARM processors, of which ran at a whopping 233Mhz. Intel later came upon work done by DEC thanks to a lawsuit, they then created XScale. This part of Intel produced CPUS that were found in a number of mobile products, most notably some BlackBerries of old along with a whole host of Windows CE PDAs back in the day as well. CPUs from the company were based of the ARMv5TE architecture. However, Intel didn’t seem to see the value in mobile and sold XScale to Marvell in 2006 for a cool $600-million.

Enough of The Old Stuff – What About Today?

Nowadays we’d laugh at a phone that launched with clock speeds under 1Ghz, less than 1GB of RAM, some of us – myself, guilty – complain at the lack of dual-core. It hasn’t always been like that however, as such ARM had to gain a foothold in the mobile world. Of course, ARM had shown that they were more than capable of creating a powerful mobile processor having shipped one with Apple’s Newton in 1993, which at the time, held a good amount of features for a mobile device when laptops needed handles. ARM processors were later featured in phones of old, such as the seminal Nokia 6110 – the first to make us play games on a phone with Snake. The architecture went on to power Gameboys, BlackBerries, Windows Mobile devices and just about any phone or mobile device. This was probably not only due to the platform’s fantastic power efficiency but also it’s flexibility and relative grunt. This has, more recently, allowed manufacturers to produce Systems on Chips – SoCs – that include processors based on ARM, Wi-Fi, GPUs etc all on one die, enabling great power efficiency and the reduction in physical footprints we’ve seen this last half a decade or so.

In more recent years though, Apple uses ARM architecture in their iDevices starting with the iPhone from 2007 which was based on the ARM11 architecture. One of the best Android phones from the last few years – the original Galaxy S – ran an ARM Cortex-A8 based core in the form of Samsung’s Hummingbird which went on to power the Nexus S as well as the Galaxy Tab. Qualcomm of course, use the architecture in their venerable line of Snapdragon SoCs – System on Chip – which powered the brilliant Nexus One and many HTC devices after it. These are all based on the ARMv7 instruction set. nVidia has made a name for itself in the game as well with its Tegra line of SoCs, delivering amazing gaming performance thanks to its GeForce GPU designed for ultra low power use. Advances these companies have made in their licensing of the architecture has led us to this point of Ghz clock speeds, dual and quad-core CPUs. Up until recently, advances in CPUs has been incremental and focussed in small areas, such as graphics with the Tegra line. However, CPUs in our phones and tablets are about to get a lot quicker, for good.

What Can The Future Possibly Hold For Us Now?

Recently we’ve seen what the ARM Cortex-A9 can do in phones such as the Galaxy S III thanks to Samsung’s Exynos 4212 Quad running at 1.4Ghz a core – which in reviews sprouting up all over suggest fantastic speeds. The very same Cortex-A9 core also powers Tegra 3, the powerhouse that makes the Transformer Prime from ASUS such a strong workhorse. However, there’s a new kid on the block that’s almost ready to hit the mainstream properly and that’s ARM’s Cortex-A15 core which they say is up to 40 per cent faster than the previous Cortex-A9. Of course, we’ve already seen this in action thanks to HTC and Qualcomm in the HTC One S outperforming the Tegra 3 quad-core in some tasks, whilst only running at a dual-core configuration. Samsung have plans to bring this awesomeness to market with their incredible Exynos 5250 – said to be easily clocked to 2.0 Ghz.

With ARM’s Cortex A15 enjoying more adoption amongst OEMs it’s going to be another few years of ever increasing speed racing to our pockets and slates. I know that I can’t wait to get my hands on an A15 based product, perhaps it’ll be the One S, or perhaps it’ll be one of the five upcoming Nexus devices – either way, the Cortex A15 core is power that’s here to stay.