What is ‘ARM Holdings’ Anyway?
There is so much confusion around the small Cambridge UK company named ARM Holdings – which had close to zero mainstream press prior to Apple building it’s A4 processor. ARM has always been known in tech circles, but now that it’s associated with consumer technology (because of Apple), I must say that almost every article I read about the company makes erroneous statements.
This is swelling over today because of the rumor that Apple may buy ARM. The misinformation is to the point that people are claiming Apple should buy Qualcomm instead of ARM, because the two are competitors – honestly this needs to stop. I thought I would write a quick post on what ARM does (and doesn’t do).
ARM does NOT ‘make’ or sell turnkey processors. What they do is control the instruction set architecture of ARM (more on that below), and license ‘cores’ to vendors. When a vendor manufactures its own processor, ARM gets a very tiny cut of the revenue off each sale (2009 revenue was only $500M).
Processor licensing is done in 2 ways:
1)Hard-core – the route most ARM licensees go. Vendors “drop in” a processor core like the Cortex A8, and build support logic around it, e.g. input/output peripheral and memory controller logic. ARM has literally hundreds of licensees who do this. Designing embedded SoC processors is not easy, but availability of hard-cores makes it much easier.
2) Soft-core – there are a few ARM licensees who customize the architecture further. Think of this as buying the basic blueprint, but then making your own tweaks to make it even better. This comes with a lot of increased responsibility and work. Ironically, Intel used to be a licensee and sold a variant of ARM (XScale) before they quit and dumped it! It’s also thought that Apple negotiated this type of license with ARM just after buying PA Semi, even though the iPad uses a hard-core Cortex A8.
Note for comparison sake that Intel does NOT license its architecture.
ARM is a low power highly efficient RISC (reduced instruction set computer) architecture. By comparison, Intel x86 is known as CISC (complex instruction set computer). ARM is not the only RISC architecture – there is also MIPS, SPARC, PowerPC (formerly used in Macs), and others. Intel’s x86 is the only high profile CISC architecture.
CISC/x86 is comprised of hundreds of instructions (individual commands) at the machine code level (assembly language). RISC-based CPUs (ARM) use much fewer instructions – only dozens.
There are all kinds of business and technical reasons why ARM is ‘better’ for the mobile market. Here is probably the biggest technical reason:
RISC instructions are fixed-length, while CISC instructions vary in length. This means that the fetch/decode process for RISC is more efficient (better use of memory resources etc). The results in a more efficient ‘pipeline’, which means lower power consumption and better battery life.
ARM in relation to Apple and Intel:
It makes more sense for Apple to join the ‘soft core’ license group (and it’s rumored they already have) than to buy ARM. Buying ARM would not give Apple much of anything other than heartburn on what to do with the hundreds of licensees. Apple can already make a modified processor ‘soft core’ and tweak the ARM instruction set, as well as use custom cell logic to do things like power and clock gating (to increase performance per watt of power consumption).
It would make more sense for Intel to buy ARM (from Intel’s standpoint). But this would be an anti-trust case in the making due to past monopolistic behavior and anti-competitive business practices. It would also be absolutely horrible for innovation so let’s hope it never happens. I personally think it could happen, but only after Intel is severely weakened by the mobile revolution and fails to gain traction with its Atom CPUs (say in 5 years). Read this for more on why Intel lost the iPad and has zero share in mobile.