System-on-Chip, and what it promises
By Dr Shawn Tan November 28, 2013
- An SoC integrates different functionalities and powerful capabilities into a single silicon device
- Many advantages to this, including size and price, but this means less ability to mix and match
AT a recent dinner with several friends, I was asked what Snapdragon was. I was tempted to answer: “Trademark,” but decided against making that wisecrack. My friends had a vague idea that it had to do with the microprocessor in their phones, but was that not an ARM processor?
I think that some people out there might also be a little confused about it. Seeing that microprocessors are my little hobby, I tried to answer their question.
The technical term for the Qualcomm Snapdragon is a system-on-chip or system-on-a-chip (SoC). It is somewhat similar to products like the Apple A6, Samsung Exynos or TI OMAP devices also found in modern smartphone devices. There are a lot of SoC devices out there.
An SoC is essentially an electronic device that contains a number of other electronic devices that were traditionally found in separate chips that took up a lot of space on a circuit board. With the magic of modern technology, we can now integrate a lot of different functionality and powerful capabilities into a single silicon device.
Hence the term system-on-chip.
Integrating multiple chips into one saves on-board space that is already very limited in our increasingly smaller phones. This means that we can all look forward to having physically smaller devices as more and more functionality gets integrated into an SoC.
Furthermore, integration improves communication capacities between the different devices, keeping all circuit paths on-chip instead of on-board. Although electrons move very quickly, it still takes a finite amount of time for them to move from one place to another. So, shorter circuit paths will improve speeds and give us a better user experience.
In addition, integration also improves power consumption by having less circuitry overall. By squeezing everything onto a single chip and allowing all the different parts to communicate directly with each other, it reduces the amount of power needed for everything, which gives us better battery life.
Let us not forget that integration also means economies of scale and brings down the cost of manufacturing. Instead of manufacturing multiple devices using different technologies and processes, a fully integrated device could be manufactured at one time, using a single manufacturing process.
Therefore, SoCs are the way to smaller, faster and cheaper gadgets.
A typical SoC would contain one or more microprocessors with a number of other peripherals or devices all tightly integrated within it. These microprocessors do not even need to be of the same type or architecture, but are commonly so for convenience. Some makers couple big microprocessor cores with little cores in order to improve power efficiency.
It is not uncommon these days to find a modern smartphone with quad-core microprocessors and graphics processors integrated into the same SoC. This is where companies like ARM come in – to supply the microprocessors that power most mobile computing devices today.
A microprocessor is essentially the brains of all modern computing devices. But for a brain, it is actually pretty dumb. It is essentially an over-powered calculator, merely capable of performing billions of computations each second and moving bits of data around.
But through the modern sorcery of software, all this calculating and moving bits around actually give us our videos, music, games, the Internet and all other manner of modern entertainment, information and communication capabilities.
So, what about Intel?
Intel is definitely a major supplier of microprocessors, especially for the desktop, laptop and server markets. However, Intel microprocessors have traditionally been sold as standalone microprocessors and not fully integrated SoCs.
Only recently has Intel released a line of Atom-based SoC for use in smartphones and tablets, which has found use by several manufacturers. It is a late entry into the mobile phone market, which is the traditional stronghold of ARM microprocessors. This is the reason why most phones run on an ARM microprocessor.
So, how does all this change our lives?
Since nearly all mobile phone SoC use ARM microprocessors, their computational capabilities are fairly similar with all else being equal. However, the difference in the types of devices integrated into the SoC by different makers mean that different devices will have different features and capabilities.
However, unlike traditional PC markets, all this tight integration means that the consumer loses the option to mix-and-match capabilities. We cannot pick and choose different microprocessor, graphics, radio and other capabilities. Consumers are only left with using the set of capabilities that the device makers have decided to put in.
One does sometimes wonder if the world would be a different place if the smartphone market developed like the PC market – where one could assemble custom hardware and load it with any software they liked instead. Wouldn't it be great if someone out there provided the tools for consumers to easily assemble their own SoC?
It seems that in our pursuit of having smaller, faster and cheaper devices, we may have sacrificed some personal freedom. If that does not matter, then it’s a non-issue.
But if it matters, supporting product ideas like Project Ara, Phonebloks and Neo900 would be a good start as it would tell device makers that consumers want more freedom. And to take things further, supporting open-source SoC efforts like ORPSoC, Milkymist and T3RAS would be even better.
Disclosure: Milkymist was originally powered by my AEMB2 microprocessor and T3RAS is the upcoming SoC from my company.
Dr Shawn Tan is a chartered engineer who has been programming since the late 1980s. A former lecturer and research fellow, he minds his own business at Aeste while reading Law. He designs open-source microprocessors for fun. He can be reached via Twitter as @sybreon.
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