Guide to smartphone hardware (1/7): Processors

With such a huge range of smartphone hardware on the market today from vendors such as Samsung, HTC, Apple, Motorola, LG and more, it can be very confusing to keep up with what exactly is inside each of these devices. There are at least 10 different CPUs inside smartphones, many different GPUs, a seemingly endless combination of display hardware and a huge variety of other bits and bobs.

This multi-part guide is intended to help you understand each and every one of the critical components in your smartphone and how they compare to other hardware on the market. Each section is intended to give you all the necessary information about the hardware, and even more for the tech enthusiasts out there, so expect them all to be lengthy and filled with details.

Over the next several days and weeks we’ll be posting up another part of the guide. In today’s guide I’ll be looking at smartphone processors: the different brands, types, how they perform and the critical differences between them.

System-on-a-Chip

This is a term you’ve probably come across before, and for good reason. When reviewers are talking about the processors inside a smartphone they are usually actually referring to the system-on-a-chip: a combination chipset that features things such as the actual processor cores, the graphics chipset, the RAM and possibly ROM as well, interface controllers for things such as USB and wireless tech, voltage regulators and more.

The idea behind a system-on-a-chip, or SoC, is that all the critical components of a device are located in a relatively small area on the device. This reduces the size of the component board needed inside and also can help make the device itself faster and more battery efficient. They also help reduce costs for assembling the product and can also be cheaper than an equivalent multi-chip set-up.

I’m more specifically looking at the processing cores inside the SoC as well as available SoC packages today, but you can look out for the other parts of this article for more detailed information on the graphics chip, memory and more.

What does ARM have to do with it?

References to ARM when it comes to SoCs can unfortunately be confusing. ARM is essentially three things: a company, a microprocessor architecture and processor core; all of which you may have guessed are related. ARM Holdings plc is the British-based company that, since 1983, has developed the ARM microprocessor instruction architecture which is used inside their ARM processor cores.

Where other companies like NVIDIA, Texas Instruments and Samsung come in is in the production of the SoCs. They take (through licensing) the ARM developed and produced processor core and put it inside their chipsets in combination with whatever GPUs, memory and other things they desire. Qualcomm is a slightly different story, but we’ll get to that later.

This is why two SoCs from different companies can both appear to contain the same processor, such as how both the TI OMAP3630 and Samsung Exynos 3310 use a single-core 1 GHz ARM Cortex-A8 solution. They are different though in their use of other components, such as how the OMAP uses a PowerVR SGX530 GPU but the Exynos features the SGX540.

The ARM1 building in Cambridge, where integral parts of smartphones are developed

The ARM architecture is something that you don’t really have to worry about when looking at a new smartphone as almost all new ARM processors feature their ARMv7 architecture. The older ARMv6 architecture was used on old ARM11 processors, which in turn were used in old SoCs on devices such as the HTC Dream (T-Mobile G1, the first Android phone) and iPhone 3G.

Currently there are two ARM processor types that are widely in use: the ARM Cortex-A8 and ARM Cortex-A9 MPCore; both use the ARMv7 architecture. Without getting extremely technical, the Cortex-A8 is usually found in single-core implementations and the Cortex-A9 in devices with up to 4 cores. The A9 is the newer implementation and as well as being (usually) multi-core, it is slightly faster per MHz than the A8 processors (2.0 DMIPS/MHz vs. 2.5 DMIPS/MHz).

You’ll find the ARM Cortex-A8 processor inside SoCs such as the TI OMAP3 series and Samsung’s SP5C series (Hummingbird/Exynos 3xxx). The Cortex-A9 is found in the TI OMAP4 series, Samsung Exynos 4xxx series, NVIDIA’s Tegra 2/3 and the Apple A5.

ARM also makes the Mali range of graphics processors, which I’ll be looking at in the graphics part of this series.

In the future we’ll be seeing SoCs that feature ARM’s Cortex-A15 MPCore, which is allegedly 40% faster than the Cortex-A9. We should see these in the TI OMAP5 series, Samsung Exynos 5xxx series and the Tegra "Wayne" series in late 2012/early 2013. In the distant future we can also expect ARM cores that use their ARMv8 architecture.

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