The 64-bit future

Apple's announcement of a 64-bit processor has the tech world debating just how far the mobile world is from upgrading its instruction set architecture

September 24, 2013 11:12 am | Updated October 18, 2016 12:56 pm IST

Apple announced an upgrade to the A7 microprocessor for the latest version of the iPhone, popularly called iPhone5. Photo: AP

Apple announced an upgrade to the A7 microprocessor for the latest version of the iPhone, popularly called iPhone5. Photo: AP

Apple Inc, in its not-so-glitzy launch show last week, made a new marketing pitch that wasn’t just about its sleek design or its funky interfaces. It announced an upgrade to the A7 microprocessor for the latest version of the iPhone, popularly called iPhone5.

But what’s new about this microprocessor? Apple is basking in the glory of beating the competition by being the first smartphone maker to announce chips that sport a brand new 64-bit instruction set. The v8 architecture, licensed from ARM Holdings, replaces the v7 used in the A6 processor that powered earlier versions of the iPhone. Apple’s Phil Schiller announced that the new chipset offers "huge benefits" including increased speed on processors and graphics.

‘Marketing hyperbole’

Following the announcements, a section of the tech world dismissed the announcement as marketing hyperbole arguing that 64-bit designs don’t push up mobile speeds in the manner that’s being projected. Others argued that while this may not make much sense or difference today, it’s an investment Apple has made that will reap benefits in the long term. Indeed, Apple’s retooled kernel and operating system and the fact that developers can start writing code in the new ecosystem (based on the 64-bit register system) will give it the first mover’s advantage.

What’s 64 all about?

So must we celebrate the fact that 64-bit computing has finally made inroads into the world of mobile hardware? To answer that let us understand the benefits of this new architecture. The number, ‘64’ in this case, refers to the number of bits of memory addresses a chip can handle. While existing mobile chipsets all handle up to 32 bits, the new architecture can handle twice the number of bits. This means the processor can handle more memory. The real benefits of such a processor can only be realised when RAM capacities are stepped up from the current 1 or 2 GB to 4 GB, which industry experts say is still a very long time away.

Following murmurs about Apple’s impending announcement, other phone makers such as Samsung announced that they were also gearing up to shift to 64-bit instruction architecture. But, getting the entire mobile ecosystem to make the shift is no mean task. This is why even ARM’s v8 chips allow the software to toggle seamlessly between the older 32-bit software and the brand new system.

The real benefits

In an interview with The Hindu , Tom Cronk, executive vice-president and general manager of ARM’s processor division, said that while it was “very exciting” to see their architecture — which took them over six years to develop and prototype — being co-opted into the world of mobile computing, the real benefits lay in the more hardcore applications such as server, enterprise or even high performance computing.

“To be honest, it is arguable if you need 64-bit computing in mobiles just yet. It’s exciting though for us to see our designs or architecture, which we’ve toiled over for the past six years or so, gain wider adoption.”

ARM spent a total of six years on this design, he explains, most of which was spent optimising what ARM calls a “clean sheet design”. “So, the V8 design has two pats to it: a 32-bit instruction set, which is compatible with everything they’ve had and run on before and there’s the 64-bit instruction set, which is a new set. So it can run all the old things, but if you write code for 64 bit it will run on it. You can run either or a combination.”

Mr. Cronk explains that the technical benefits of this architecture are two-fold: it allows you to address a bigger code space, so you can address more memory. The other benefit is that it gives you some more performance. How much more depends on the way you build your chip. But, where you really need this architecture is on other applications such as the server space, for instance, he says. “There you need the extended address range. In the server space we’re already winning designs in some sub-segments but this 64-bit architecture opens up a whole new market for us. It has been a massive accelerator for us.”

Still a single digit presence in the server markets, ARM hopes to speed up its growth trajectory in this important sector with its v8 designs.

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