Desktop computer workstations with 64-bit processors are now commonly found in advertisements presented to home and small office computer buyers. Dell is offering 64-bit desktop systems with Intel Xeon and AMD Athlon 64 CPUs. Apple has had 64-bit Power Mac G5 systems for years and now also offers an Intel Xeon-based Mac Pro with four 64-bit cores. Do-it-yourselfers can easily buy 64-bit motherboards for Intel and AMD 64-bit processors from hundreds of vendors on the Web.

There are also 64-bit versions of Mac OS X (10.5), Linux, and Microsoft Windows XP and Windows Vista to run on 64-bit hardware. Software developers are now writing true 64-bit programs that can make full use of the resources of 64-bit operating systems, and not simply rebuilding 32-bit programs with a 64-bit compiler. Power, speed, and capacity for the future are all part of the 64-bit promised for consumers.

But, despite the increasing available of 64-bit technology, do you really need a 64-bit desktop computer?

Computers with 64-bit architectures have existed for decades, starting with the IBM 7030 introduced back in 1961. Most 64-bit computers are used for working on extremely large amounts of data and for implementing high-performance database systems. The primary benefit of a 64-bit computer is the ability to store and move extremely large amounts of data in memory and very quickly. Conventional 32-bit systems can only store and move about 3GB of data in memory, while 64-bit systems can move many thousands of times that amount of data. It much faster to work on data while it is entirely in memory, and that is a reason why the scientific and engineering communities love 64-bit computers and the massive amounts of memory they support.

The largest amount of RAM supported by a 32-bit processor is 4GB, and the largest 32-bit unsigned integer value they can store is 4,294,967,295. In comparison, the largest amount of RAM supported by a 64-bit processor is 16EB (Exabytes), and the the largest usable 64-bit unsigned integer value is 18,446,744,073,709,551,615. Despite this unimaginable amount of memory addressing capability, 64-bit operating systems and hardware architectures typically limit the amount of usable RAM to between 16GB and 1 Terabyte (1024 GB). Even with this imposed limitation, it will be a long time before even Google finds a way to put a full Terabyte of RAM to good use.

Although 64-bit computing is where humanity seems to be headed, you do need to consider if now is the time for you to make the move to 64-bits. Consider the following problems currently faced by the owners of 64-bit computers:

• Very expensive to buy a 64-bit system
• Very expensive to own a 64-bit system
• Cannot use all of the same hardware peripherals as on a 32-bit computer
• A 64-bit program does not seem to run any faster than its 32-bit equivalent
• 32-bit programs seem to run slower on a 64-bit computer than they do on a 32-bit computer

The first big problem with 64-bit computing is the expense. 64-bit systems are much more expensive than their 32-bit counterparts. The processors, motherboards, enclosures, and power supply units are all top-of-the line. The cost really soars when you consider that you will be also buying very fast hard drives and much more and faster RAM for your high-performance 64-bit system. You will also find that, unless you want to run a free distribution of Linux, 64-bit operating system software and applications can be very expensive too.

After your first month of 64-bit computing, you may notice that you need to run the air condition in your room a lot more. You’ll also notice that your monthly electrical bill has also increase somewhat. It seems those 64-bit dual- and quad-core systems require more power and more cooling too. You will soon find that there is nothing cheap about 64-bit computing.

The next problem is the lack of hardware drivers for 64-bit operating systems. There is no 32-bit emulation mode for hardware drivers. Each driver must be re-written as needed to fully port it to a 64-bit architecture. Many consumer hardware manufacturers still don’t consider the 64-bit market large enough to bother with providing 64-bit drivers for their devices, so your favorite USB-enabled toys may not work on your new 64-bit system.

One common assumption is that 64-bit systems are faster than 32-bit systems simply because they have twice the bits. A processor is described as being “32-bit” or “64-bit” based on the size of its registers. A register is an area in the processor where an instruction may read or write an integer or floating-point value. The registers in a 64-bit processor are not only twice the size as those in a 32-bit processor, but there are also more of them. It is the register size and the number of registers that allows a 64-bit processor to be a more superior number cruncher, but not necessarily faster, than a 32-bit processor. When comparing processors, it primarily the clock rate of the processor and the amount of on-chip cache it supports that determines its performance, not the size of its registers.

Finally, not only will your 32-bit programs not run any faster on a 64-bit computer, they may actually run a little slower. In a 64-bit operating system, 32-bit programs cannot run in 64-bit native mode, and instead must run in a 32-bit emulation environment. This environment allows the 32-bit programs to operate as they would in a 32-bit operating system. Running in emulation mode is slower than running in native mode, which only 64-bit programs can do, and does not allow 32-bit programs complete access to the system. Only a program written and compiled for a 64-bit OS can potentially have full access to all of the resources of the 64-bit system. In the emulation environment, a 32-bit program might be given a full 4GB of RAM to use, but that’s about it.

In summary, here is what 64-bit computers are really useful for doing:

• Storing and moving many gigabytes of data in memory
• Crunching very large integer or floating point values
• Very high performance, high volume database systems
• Virtualization, in which separate program runs in their own, gigabyte-sized virtual memory space

Unless you really need a computer for one or more of these uses, you do not need a 64-bit computer.

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This entry was posted on Sunday, May 13th, 2007 at 5:11 pm and is filed under JDMurray. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.