Tech Primer

64-bit computing

What is a 64-bit processor?

The bit-rating of a processor determines the largest numerical number it can handle. A 32-bit processor can handle a number up to 232 or 4 GB of RAM memory. In a 32-bit system, this 4GB of RAM is, in turn, divided between applications and the operating system. Of the 4 GB, the operating system can only allocate 2 GB of memory to a given application. Compared to a 32-bit processor, a 64-bit processor can handle more memory (up to 1 terabyte of virtual memory) and larger files. This is far beyond what the memory manufacturers can offer or supply today. Additionally, a 64-bit operating system can allocate an individual memory chunk of 4GB for each application.

What are the potential application areas for 64-bit computing?

64-bit computing has been used over the past decade in supercomputing and database management. It is in the scientific and data management industries that the 4GB memory limitation of a 32-bit system has become a bottleneck. Other sectors where 64-bit CPUs may have a significant impact are 3D animation and graphics, engineering institutions running large projects and financial institutions such as the stock exchanges.

What are the benefits of 64-bit computing?

Companies that need to access huge amounts of data are already using 64-bit servers. This is because a 64-bit server can effectively load large enterprise databases into memory permitting faster searches and retrieval of data. Additionally, using a 64-bit server means that organisations can support more simultaneous users on each server potentially removing the need for extra hardware as one 64-bit server can stand in for several 32-bit servers. The benefits of 64-bit processors are apparent when demanding-applications such as video-rendering, scientific research and massive database searches are run. In short, tasks that require the ability to load massive amounts of data into the system's memory benefit from 64-bit processors.

Are there any issues with 64-bit systems?

A 64-bit processor with a 32-bit operating system will end up wasting processing power. This is a chicken-and-egg situation for both the hardware and software makers. Software companies do not want to write new software until organisations actually start buying 64-bit processor systems. The hardware vendors face a problem as they cannot sell their product unless there are applications running on it. This is not a problem on RISC processors that made the shift to 64-bit a long time ago. It is a problem for non-RISC 64-bit processors. AMD has addressed this problem by designing its processors to handle x86 32-bit operating systems with the addition of 64-bit registers. This allows the processor to run both 32-bit and 64-bit applications. The 64-bit Xeon implements a similar approach.

Any takers for a 64-bit desktop?

As most home users don't have a PC with 1 GB of memory, the market for 64-bit desktops does not seem to exist. However, this has not deterred vendors such as AMD from launching 64-bit desktop processors. AMD is betting that the odd gamer or video editor will be consumers for 64-bit desktops built around its processors. HCL, Zenith and Wipro have launched branded PCs built around AMD's 64-bit processor, the Athlon 64. Most analysts believe that it will take at least three more years before 64-bit desktops start making an impact in the market.

For an 'Introduction to 64-bit Computing and x86-64' check out the following link http://arstechnica.com/cpu/03q1/x86-64/x86-64-2.html