At the unveiling of the iPhone 5S in September, Apple senior vice president Philip Schiller repeated one term again and again: 64 bit.
The phone's new processor, he said, "is 64 bits. This is the first ever in a phone." In October, Mr. Schiller boasted that the iPad Air would also hop from 32 bit to "desktop class" 64 bit. So what does 64 bit mean?
It has to do with the way a processor in a computer accesses the RAM (the memory). RAM can only handle so much data at once and labels each piece of information with an address. These addresses are written in bits – essentially 1s and 0s. In a 32-bit system, each label is 32 1s and 0s long. That many bits has worked well for decades because the system can juggle as many as 4 billion addresses before running out of new numbers.
In PC-shopping terms, that means a 32-bit computer can handle as many as 4 gigabytes of RAM – but no more than that. If you want more memory, you'll need to bump up to a 64-bit system, which can handle longer and therefore more RAM addresses.
A 64-bit computer can work with as many as 17 billion gigabytes of RAM – way more than you'll need anytime soon. Many new laptops and desktops still don't come with more than 4 gigabytes of RAM.
Simply running at 64 bits doesn't ensure better performance. The Nintendo 64 played video games in 64 bits back in 1996, even though the games on that system were demonstrably less powerful than many games on Apple's old phones. In reality, performance comes from the interplay between the speed of a processor, the memory capacity, the graphics card, the operating system, and whether the software is written to take advantage of each. That's why Apple released its 64-bit software on the same day that the iPhone 5S arrived in stores.
Microsoft has had a 64-bit version of Windows since 2001, well before most machines could take advantage of it. While Apple pushed its top-of-the-line phone, tablet, and software up to 64 bits all at once, the PC industry has slid toward wider adoption over many years. Windows 8.1, which debuted in October, still comes in 32- and 64-bit flavors.
If you're in the market for a new PC, don't assume a 64-bit machine is worth the extra money. Processor-heavy programs such as Photoshop and video-editing software would love access to more RAM, but most applications run fine on fewer than 4 gigabytes. Plus, software written for 32-bit systems usually work on 64-bit machines, but some things (such as security software and old printers) will not.
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