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ARM — Heretic In the Church of Intel, Moore's Law
ericatcw writes "For 30+ years, the PC industry has been as obsessed with under-the-hood performance: MIPs, MHz, transistors per chip. Blame Moore's Law, which effectively laid down the Gospel of marketing PCs like sports cars. But with mobile PCs and green computing coming to the fore, enter ARM, which is challenging the Gospel according to Moore with chips that are low-powered in both senses of the word. Some of its most popular CPUs have 100,000 transistors, fewer than a 12 MHz Intel 286 CPU from 1982 (download PDF). But they also consume as little as a quarter of a watt, which is why netbook makers are embracing them. It's 'megahertz per milli-watt,' that counts, according to ARM exec Ian Drew, who predicts that 6-10 ARM-based netbooks running Linux and costing just around $200 should arrive this year starting in July."
ARM chips are nice, but they are not as fast as Atoms and their low power usage does not guarantee long battery life. It needs to perform at least on the level of a Dothan 600MHz before I'm interested - web surfing is already a pain at that level of performance.
They are the only chips that you can program and keep your sanity.
The ARM code is just beautyful design, one weeps with joy after struggling through x86 hell.
And computing/electric power ratio is fantastic.
ARM has a couple processors already that are pretty high on the performance measurement. For instance the Arm Cortex A9 has a dual issue pipeline, and limited support for out of order processing (similar to the original Pentium processor in that regard). This chip also can contain up to 4 cores, and have up to a 2MB L2 cache. I think they can run up to about 1GHz. They also have full support for floating point and all that good stuff. I'm pretty sure ARM is also working on developing an true OoO processor that will likely be running in the GHz range which would likely be ideal for a netbook.
Remember, with a netbook, you don't gain much by lowering the CPUs power consumption to less than 5 watts or so. The reason for this is simple, the display, ram, hard drives and everything else consume enough power that it won't really help battery life very much. I can imagine though that a quad core ARM A9 at 1GHz would make for a really nice netbook. Having multiple cores is nice on those for web browsing (playing flash in the background of your tabs, etc), and also for many media tasks. It would also be great if they included a graphics chip (or gpu as part of a SoC system) that could handle h.264 decoding for the netbook.
Phil
The trick is that the ARM instruction set is *WAY* more efficient than the x86. The fact that the current ARM's are basically in order units is less important due to the design of the instruction set.
A minor correction here: The ARM instruction set is simpler and is much less feature rich than x86. This, combined with self imposed limitations (mostly around in-order execution) ARM (the company) is able to design CPUs with a much lower transistor count than x86 chip designers are capable of managing.
Not having a huge instruction decoder, having to do instruction reordering, or basically doing any of the things that makes x86 so damn fast, and staying a generation or two behind on manufacturing techniques to avoid leakage issues, enables ARM CPUs to have their amazing power profile.
The instruction set is kind of a mess really. It has been hacked onto a number of times, with the latest additions really showing signs of having wedged into the existing instruction encoding space. With features like the original (crappy) thumb, and now the fixed "Thumb2" (which we are all supposed to be calling Thumb and ignore the old Thumb, or something like that), and the fark-up that is ARM's floating point support (They have 3 implementations, 2 of which are still in use, and those two versions respond dramatically different to some basic key floating point operations), the ARM instruction set isn't nice per say, but ARM did the right thing and by keeping their eye on power consumption always.
(For those who are getting linguistically confused: ARM the name of the company, the name of their CPU line AND the name of their instruction set. Oh it is also the name of their reference manual, the ARM-ARM.)
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