If you have an iPad, iPhone, a Galaxy Tab or
pretty much any other mobile device today, it's very likely it's powered by a
chip from ARM. Now the company is eager for a much bigger slice of the
Computing pie.
The
ARM 1 CPU in an Acorn ARM Evaluation System
The first ARM processor was born from the
design efforts for the Acorn Archimedes personal computer. Like its predecessor
the BBC Micro, also made by Acorn Computers, the Archimedes found a niche for
itself in the education market in the UK. That niche switched over to more
capable and more widespread Apple and IBM-compatible computers as the 1980's
ended, leaving Acorn Computers and its processor design high and dry.
Fortunately, Apple and a few other investors joined with Acorn to establish
Advanced RISC Machines or ARM to further promote the technology, with Apple
even using it for its groundbreaking Newton personal digital assistant.
ARM is a chip company that doesn't make
chips. It designs instruction set architectures, processors and GPU cores for a
variety of applications and licenses them to other companies which can
manufacture those designs or modify them further. Unlike in the desktop arena,
its chips don't get much attention by the general public. Companies like Apple,
Samsung, NVIDIA and Tl license ARM processor cores such as the Cortex A8 and
Cortex A9 and integrate them into their own designs for the systems-on-chip
(SoC) that run on tablets and smartphones, combining those cores with their own
imaging and signal processors, memory and network controllers and wireless
radios.
ARMv7
Others like Qualcomm license a particular
instruction set architecture such as ARMv7 and design their own processors like
the Snapdragon that are compatible with it. The beauty of licensing is that
applications that target one instruction set and processor family are broadly
compatible with similar licensed SoCs - witness the number of Android devices
running on cheap-as-chips Rockchips processors to the top of the line Samsung
Exynos. If you wrote something for a Cortex A9, chances are it would also work
with an A9-based chip from another manufacturer.
The hallmark of ARM cores has been power
efficiency because of its small instruction set and reduced transistor count.
The latest smartphones sport dual-core, even quad-core processors running at
over 1 GHz yet can run for hours on batteries. For example, NVIDIA's Tegra 3
SoC combines four A9 cores with a hidden, low power A7 core and a GPU core in
just a few square millimeters - the big quads are activated when a complex web
page needs to be rendered or a game is running, but for common system tasks
they're turned off and the tiny A7 takes over while sipping electrons. For
watching high-resolution videos, the GPU itself can handle all the decoding
while the rest of the system is shut down. The ability to run at full speed
without a heatsink and fan while consuming just one to two watts makes SoCs
like these invaluable, sandwiched in the tiny spaces in today's thin mobile
devices.
The combination of low power and high
performance are making ARM processors look attractive outside the mobile
industry too. For server farms, computers that sit around without doing any
work cost money in terms of electricity and cooling, so having an army of slower,
more frugal processors continuously crunching on distributed tasks like web
serving or database processing (the typical Linux/Apache/MySQL/Python LAMP
stack) can make economic sense against speedy processors that consume twenty
times more power at idle.
The
Armada XP
ARM SoCs for servers such as the Marvell
Armada include memory, PCI-E and SATA bus and Ethernet network controllers on
the processor, saving even more power compared to discrete components on
typical server motherboards. The existing 32-bit architecture might be good
enough for phones but it's not enough for servers that handle lots more memory,
hence the introduction of the new ARMv8 64-bit architecture. ARM itself hasn't
finished designing a 64-bit core but its partner Applied Micro has - the X-gene
SoC is supposed to idle at a tiny 300mW, run at full power at 2W per core and
includes such server goodies as hardware virtualisation and ECC memory support.
Of course, this also means ARM SoCs can go
into laptops. Imagine one that can comfortably run common applications like Web
browsers and office suites while lasting an entire day on battery power... not
so farfetched when anorexic tablets already surpass the ten-hour mark, but
that's with lean mobile operating systems optimised for low power consumption.
I wouldn't mind trading pure processing power - which is rarely used anyway -
for sheer longevity. Ubuntu Linux has an ARM version for testing and the
upcoming Windows 8 supports an ARM tablet variant, so we could be seeing
netbooks or even laptops running desktop-grade operating systems on ARM by the
end of the year.
I can't wait to get one under my, well,
arm.
