Why does the new iPhone have a 64-bit processor?

Why does the new iPhone have a 64-bit processor?

Nov 12th 2013, 23:50 by G.F. | SEATTLE

SINCE its resurgence in the late 1990s, Apple has generally shied away from trumpeting processor speeds, cache sizes or other technical details in its marketing materials, preferring to emphasise what its products can do, rather than what is inside them. It does make exceptions, however, as in the case of the recent launch of the iPhone 5s, its new flagship smartphone. Executives hyped its “64-bit” A7 processor, which they asserted had desktop-computer performance and could complete some tasks twice as quickly as the 32-bit chip in its previous model. Rivals, bloggers and technology-news sites disparaged its claims, saying that there was no good reason to put a 64-bit chip in a smartphone except to claim bragging rights. Anand Chandrasekher, the chief marketing officer of Qualcomm, a rival technology firm, told Techworld: “Predominantly…you need it for memory addressability beyond 4GB [gigabytes]. That’s it. You don’t really need it for performance.” Yet the performance boost is there, as independent benchmark testing confirms. Why has Apple made the jump to 64 bits?A central processing unit (CPU) is the number-crunching brain of any digital device, whether it’s a laptop, phone or Mars rover. A CPU is capable of performing various basic mathematical and logical operations: divide this number by that number, say, or compare two values and jump to a different point in the program depending on the result. As Steve Jobs once observed, all computers do is fetch and shuffle numbers, but do it fast enough and “the results appear to be magic”. One difference between a 32-bit chip and a 64-bit chip is that the latter can fetch or shuffle twice as many bits with each tick of the processor’s clock, thus performing computationally intensive tasks more quickly. Another difference, as Mr Chandrasekher correctly noted, is that a 64-bit chip can more easily support larger amounts of random-access memory (RAM). No single program running on a 32-bit processor can, without a lot of fussing, use more than 4GB of memory, which can be a problem when managing large data sets or handling extremely complex graphics. Such programs tend not to be used on smartphones or tablets, but run instead on desktop, laptop and server computers, which made the jump to 64-bit chips some years ago.

But by putting a 64-bit chip into its latest smartphone (and its new iPads), Apple is recognising that they are increasingly being expected to perform heavyweight computing tasks for which people would previously have used “proper” computers. For many people, tablets have already replaced laptop computers for a wide range of tasks, and the proportion is only likely to grow. (Phones and tablets have become the most popular devices on which to play games, which are also computationally demanding.) The appearance of a 64-bit chip in a smartphone is, in short, yet another example of how phones and tablets are displacing PCs as the most popular and widely used computing devices.

For Apple, which has been the greatest proponent and beneficiary of this trend, being able to brag about the chip in its new iPhone is merely an added bonus. Other manufacturers are sure to follow suit with 64-bit mobile devices. Within the next couple of years, more tablets and smartphones will want to cross the 4GB RAM barrier. Qualcomm, Samsung, Nvidia and others are all expected to release 64-bit mobile processors of their own, in many cases based on the same architecture that Apple has licensed from ARM, a British chip-design firm. Samsung is aiming for 2014, and Qualcomm, which acts as a supplier to handset-makers, will soon be trying to convince them to buy 64-bit chips. Little wonder, then, that Qualcomm’s press relations team quickly repudiated Mr Chandrasekher’s claim that beyond being able to support more RAM, there was “zero benefit” to 64-bit chips. There is—which is why Apple has adopted them.