Why is it that most Single-board computers are based off the ARM chipset instead of x86-x64?

Question

I'm not sure if anyone has really noticed or paid attention, but i have noticed ever since the single board computer has taken off (like the Raspberry pi) that they are mostly ARM based, why is that? I think it would be a lot easier if they were x86-x64 based, because it would be easier to use programs that you are used to using instead of finding ARM versions.

rew · Answer

Many embedded processors are ARM processors. They are better suited for embedded stuff. One of the things is that they get more computing work done per unit of energy consumed. Secondly, there are many "system on a chip" (SOC for short) ARM processors. Like the BCM2735. That integrates lots of peripherals into the chip so that you don't need extra chips. So take a look at the raspberry pi zero... You have a single board computer there with HDMI output, a storage interface and half a gigabyte of RAM. All in that single black blob in the middle! Intel has been trying to get "in on the action" for over a decade now. They haven't been really successful, because their processors require too much support hardware around them, meaning the boards get big and expensive. So for example: https://azerty.nl/0-843-709774/intel-next-unit-of-computing-board-de3815tybe-moederbord-ucff-intel-atom-e3815-usb-3-0-gi… which doesn't even have RAM but is 4x more expensive than a raspberry pi. And it requires a bigger powersupply. (in my quick search for something like this, I found a EUR 73 board, but that was just the breakout for another intel board....) The cheapest Intel CPUs come in at around EUR 40. extreme low-end ones maybe half that.... An ARM CPU can be bought for 32 cents! Ok, that's a low-end ARM V6...... hmm... just like the raspberry pi (1). OK, that one doesn't have everything the raspberry pi CPU has, but it can be bought for way less than $1 in low quantities. At higher quantities the raspberry pi CPUs apparently also cost only $1-$2. The RAM is probably similar, and they sell at $5 (for the zero).

clem57 · Answer

I think this sums up the differences best Intel x86 Microprocessors vs. ARM Microprocessors . This part shows best the reasons: Licensing makes it possible for a company to develop a custom solution for their hardware, which in turn results in better power efficiency and lower costs. Because Intel does not license x86, anyone who wants a x86 processor must buy a full processor from Intel (or AMD or VIA). ARM processors can be custom-tailored to a specific product. This is why ARM Holdings, the company that licenses the ARM instruction set, often boasts that ARM processors are more popular than x86. They are, by unit volume, correct. There are far more ARM processors put into products because ARM processors can be custom-tailored to fit so many different roles, embedded into places where we don't even think of them, such as automotive technology. Clem

lex_b · Answer

Enrico, What you, "think" is correct, actually isn't. I am hardware and software engineer that works on desktop, servers, super computers and embedded systems. The only thing that is different on the embedded ARM series CPUs versus x86 / x86_64 that you need to be concerned with is the different instruction set and registers. Since a good C/C++/C# cross compiler from GNU or LLVM, there's not too much trouble creating drivers, operating system images, support libaries and ultimately the applications sitting on top of all of this. The only real difference from a programmer's point of view (meaning not doing anything in assembly language) from C/C++/C# is setting the compiler flags to optimize for size vs. speed. The ARM series of CPUs and APUs have two byte ordering modes, big and little endian. Every little SBC I've seen have been hardwired for little endian mode, just like the x86 and x86_64 are (which they don't have the ability to switch back and forth). The advanced CPU and APU architecture of the SBC allows for some really cool capabilities with very little memory. The vast majority of why PCs are slow slow are all the hardware and software interrupts. The embedded ARM solutions only have as many interrupts as they need absolutely which is far less than the PC. Programming these SBCs are very similar to the desktop except you don't have to guess the hardware or try to search for it, you already know what is there, the drivers very rarely need to be changed unless their buggy or seen to be dangerous in regards to security of personal information. From an operating systems standpoint already running and you have a keyboard with a mouse connnected. Running the Python or Perl scripting languages run just the same as on the desktops or servers, let alone on the embedded system. The reason why the operating system images on the desktop and servers are so big is because you have all these different configurations with different chipsets for LAN, audio cards / chips, graphics cards / chip, different CPUs with slightly different instruction sets. Of course, the applications are built for compatibility or absolute speed (this takes up a lot of space on the disk and in RAM). Most embedded systems are capable of OpenGL 4.x but many focus on OpenGL ES version 1.0 ~3.2, which is a more stripped down version of OpenGL core profile, as the core profile is a stripped down version of the compatibility profile (full specification). To be honest with you, the ARM CPU and APUs that have 8 or 10 core in embedded systems are actually a lot more powerful than the 8 and 10 cores on the Intel and AMD side, even at a lower frequency and use a lot less power. The Qualcomm Snapdragon 600 embedded and 800 mobile series are quite remarkable acheivements. My favorite is the Snapdragon 835. I also use the ARM Cortex A-73 in embedded systems and a design as a desktop with slots I can plug accessories I'm developing into the system. The desktop computer I've developed uses standard PCIe 3.0 x16 slots, of course I have other chips handling that I/O and interface logic but the embedded system chips can be used just the same as standard desktop chips are used.

rew · Answer

I have a few hundred ARM cpus where Licence + cost-to-make-a-chip is below $0.32. I bought them because I couldn't believe they could make them for that kind of money.

johnbeetem · Answer

Douglas Wong wrote:

Intel did license their technology - How many companies make a variant of 8051?
ARM must have been a much lower cost license....

I recall that Intel did try to license Atom several years ago to compete with ARM in the embedded space. I don't recall exactly why it was a disaster, but I think it was primarily that Atom was much more expensive than ARM for similar performance. I think Atom's power consumption was competitive, but still not as good as ARM which has pushed low power ab ovo.

ARM license fees have traditionally been very low. They prefer volume over high per-unit cost. Intel remembers that IIRC the brand-new 8080 sold for $300 in single units and prices their chips accordingly. Intel is a much bigger company with much higher overhead. ARM began with basically no money and basically no staff so they have always been very frugal.