Microprocessors are mainly of two types—those which work on a PC and those which work on handheld devices. This is not a strict difference; the ones that work on PCs could also work on tablets with necessary tweaks and changes. However, it all depends on the architecture used.
The operating systems you know, such as Android, Apple iOS, Windows, BlackBerry, all depend on the architecture of the processor used on the system. The two main architectures out there are ARM and Intel X86. X86, which we will not deal with here, is for PCs running mainly Microsoft Windows operating systems, the desktop versions of course.
The ARM architecture developed and maintained by UK company, ARM Holdings, ltd., is an architecture mainly for mobile computing: tablets and smartphones. And a number of mobile operating systems (perhaps all of which you know) use ARM architecture. This is not a proprietary technology, but a standard. That means, companies can license ARM architecture and build processors of their own to use with tablets.
Many companies have licensed ARM architecture, and they include biggies like Texas Instruments (TI), AMD, HP Digital Equipment Corporation, NVidia, Qualcomm, Samsung, Panasonic, LG, etc. Android, iOS, BlackBerry, Bada, WebOS, and almost all of the mobile operating systems we know use ARM architecture processors.
Tablet processors are generally known as System on Chips (SoC) due to the fact that almost all of its functionality is found on a single microprocessor chip.
The main processor brands which are based on ARM include Samsung Exynos, Texas Instruments OMAP, NVidia Tegra, Qualcomm Snapdragon (using slightly different Krait architecture), etc.
ARM Cortex Series
When you buy an Android tablet, one of the first things you look for is the technical specifications. Among them, the processor details are important. ARM Cortex is a series of processor architectures (cores) published by ARM. Independent companies can license these architectures and build their own processors.
Before Cortex brand was released, ARM architectures were named ARM7, ARM9, and ARM11. They are no longer used in any tablet computer. Right now, the ARM Cortex-A8, Cortex-A9, and Cortex-A15 are used by companies. When you buy a tablet, it would be helpful to know which series the processor belongs to.
All of these processor families use ARMv7 instruction set architecture. This is different from the processor architecture, and the upcoming instruction set architecture is ARMv8 that will support 64-bit apps.
a. Cortex-A8
These processors generally give up to 1 GHz of processing power, and they are used in the development of Apple A4, TI OMAP 3, Samsung Exynos 3110, etc. This architecture was used in yesteryear Android tablets including Barnes & Noble Nook Color (TI OMAP), the original Samsung Galaxy Tab (Exynos 3110), etc. Cortex-A8 is already outdated and you should not purchase any tablet with this architecture any more.
b. Cortex-A9
More power-efficient and allowing higher clock speeds (GHz) than Cortex-A8, A9 processors include Samsung Exynos 4 series, NVidia Tegra 2 & 3 series, etc. The Android tablets you can buy running this architecture include Tegra-powered Asus Transformer Pad, Motorola Xoom, Sony Tablet S, etc., and Exynos-powered Samsung Galaxy Note 10.1, Galaxy Note II, etc.
Still, if you ask me, Cortex-A9 is almost getting outdated, and I would purchase a more future-proof processor.
c. Cortex-A15
The answer to the future-proof processor is Cortex-A15. These processors can support RAM up to 1 TB, and processor speeds well exceeding 2 GHz. TI has developed an embedded processor solution called Keystone that runs at clock speeds of nearly 9 GHz based on Cortex-A15 architecture. The main mobile processors working on A15 are Tegra 4, Exynos 5, OMAP 5, etc.
The major Android tablet that you can purchase with this architecture is Google Nexus 10, the tablet developed by Samsung.
d. ARMv8 and Cortex-A50
Soon enough, ARM will transform to the next level of instruction set architecture, ARMv8, and already the processor architecture based on this, Cortex-A50 has been confirmed. The advantage of ARM Cortex-A50 is the ability to work with 64-bit apps.
Right now, there are no tablets or smartphones running Cortex-A50 processors like A57 and A53. However, if you could wait a little bit, you can purchase Android tablets running A50 based processors.
Qualcomm Snapdragon (Krait Architecture)
We have been looking at ARM’s Cortex architecture, and we never mentioned Qualcomm and Snapdragon processors. Qualcomm is one of the major providers of tablet processors. Qualcomm has its own processor architecture known as Krait, loosely based on ARM architecture. It is in fact an improved version of existing ARM Cortex.
Qualcomm Krait powers the processors in the Snapdragon series. Krait stands in between ARM Cortex-A9 and A15. Closely related to A15, and thus regarded to be more advanced than most of the A9 devices out there.
Existing Snapdragon processors are…
a. Snapdragon S4 Play: based on Cortex-A5; old smartphones used to have these processors. No longer used in any tablets out there.
b. Snapdragon S4 Plus: based on dual-core Krait architecture; one of the major Android tablets running S4 Plus is Asus Transformer Pad Infinity (the 3G/4G version, not the Wi-Fi version that runs NVidia Tegra).
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| Well designed Asus Transformer Pad Infinity uses Snapdragon S4 Plus on 3G version |
c. Snapdragon S4 Pro: Pro is based on the same architecture but includes four cores (quad-core). A tablet running this processor is 5-inch HTC J Butterfly.
d. Snapdragon S4 Prime: Quad-core processors mainly used for mobile TV experience. There are no known products based on this processor at present.
In the Consumer Electronics Show in Las Vegas, Qualcomm released the latest edition of its Snapdragon processors, Snapdragon 800 and 600.
The Buying Decision
When you purchase tablets, you should look at the tech specs and specifically the processor details. It doesn’t matter whether the company is Samsung Exynos or NVidia Tegra. The processor architecture has to be current; that means minimum ARM Cortex-A15 or at least Qualcomm Krait.
Cortex-A9 is on the verge of getting outdated. A15 and soon to be released A50 are what you need to look for in the future tablets.
Second most important thing is the processor speed. This is given in Gigahertz (GHz): the higher, the better. Also, the speed of the processor is closely related to how many cores it has (dual-core or quad-core based on current standards). A quad-core chip may perform better than a dual-core one even if the speed is slightly lower. Also, an A15 dual core chip may be faster than A9 quad-core chip.
Conclusion
When you buy a new Android tablet, getting one with the latest CPU specification is pretty important. Since the world of desktop computing has already migrated to 64-bit, it is perfectly logical to expect 64-bit programs also for tablet computing. Thus, the upcoming Cortex-A50 architecture makes sense in tablet computing.
[Images: Popsci.com, Engadget, Asus]