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The 64-bit question

Posted on 10 Dec 2002 at 17:57

Both Intel and AMD are releasing new 64-bit processors, but who are they for and why do we need them? Alan Stevens investigates

It's unlikely you spend much time pondering the number of bits a processor can handle. However, recent developments could make it an issue affecting everyone. The 64-bit question has implications for all of computing, but will the impact be as great as 32-bit?

Of course, 64-bit processors are nothing new - they've been around in RISC (Reduced Instruction Set Computer) servers and workstations for years, and more recently in games consoles. However, the landscape is changing, chiefly through the involvement of mass-market chipmaker Intel and its rival AMD, both of which announced new 64-bit chips in 2002. If history is anything to go by, this would imply an impending commoditisation of the technology, leading not just to more affordable 64-bit servers, but also 64-bit desktops, notebooks and PDAs over the next few years.

But is that really on the cards? Do we need 64-bit everywhere anyway? There are also software implications to consider - are 64-bit applications any better than 32-bit, do they run any faster, and can you run existing 32-bit programs on the chips now starting to appear? Moreover, is any 64-bit software actually available for these processors?

Questions like these need to be answered to get beyond the hype and commercial forces currently driving 64-bit technology. In this feature, I'll be looking at the latest 64-bit processor developments and putting them into perspective for those of us living in the real world. As such, a good place to start is with a short layman's guide to what 64-bit computing is all about and what sort of applications it's good for. Then I'll look in more depth at what the new chips from Intel and AMD have to offer, along with the software implications, and where the major system vendors look set to take 64-bit over the next few years.

More bang for your bits
Potentially, there are many things 64-bit processors should do better than their 32-bit counterparts. That said, most advances hinge on the ability to work with larger numbers, which, not surprisingly, can be up to 64-bits long. This allows, among other advantages, for a higher level of accuracy when it comes to big floating-point calculations. But this would seem to be of little value outside the realms of scientific apps - such as mapping of the human genome - and unimportant for corporate transaction processing or servicing web and email servers.

Of wider importance is the ability to address a larger amount of memory. The amount varies depending on the implementation and operating system, but Windows' limit for a 32-bit processor is currently 4GB. With a 64-bit processor, however, you can, in theory, directly address up to 8TB - 2,000 times as much.

While 4GB of memory should be more than enough for desktop applications, in a server that amount is soon used up. The extra space possible with 64-bit addressing would enable much larger SQL databases to be loaded and run in memory, and whole websites to be resident in RAM. As RAM is so much faster than disk, the potential benefits are easy to grasp - programs will run faster, more users will be supported on the same hardware, more complex transactions accommodated and so on.

Properly exploited 64-bit addressing may benefit scientific and technical computing as well as the big transaction-processing systems deployed by large enterprises. As a consequence of design, other features of 64-bit processors can fulfil the larger transaction requirements of enterprises right down to those deployed in smaller companies and on the desktop.