32 Vs. 64: What Bit Windows?

You can run today's versions of Windows on 32-bit processors--a standard that's been around for about 25 years--and on newer, backward-compatible 64-bit processors. Of course, everything has to have an acronym in this industry, so the Windows-compatible 64-bit standard is also known as x64. That's fine, but the 32-bit standard is abbreviated as x86. If you don't understand the history, that's just plain confusing.

Because x64 processors are backwards-compatible, you can install and run 32-bit as well as 64bit versions of Windows onto them. Of course, if you bought an x64 computer from a major manufacturer, it almost certainly came with 64-bit Windows pre-installed.

You cannot install or run 64-bit Windows on a 32-bit PC.

The 64-bit version of Windows has certain advantages. While the 32-bit version is limited to 4GB of RAM--and can't really make use of all that--the 64-bit version can address up to 8TB. While you won't be able to actually install that much RAM (or afford it) for a long time to come, you can buy a 64-bit computer today with 12GB installed.

Speaking of things that aren't quite there yet, 64-bit applications should run faster than their 32-bit equivalents. But as I write this, very few native 64-bit applications exist, and they're not necessarily improvements (most 32-bit applications run just fine in Windows x64). In fact, although Microsoft Office 2010 comes with 32- and 64-bit versions on the same DVD, Microsoft recommends you install only the 32-bit version.

And, of course, 64-bit Windows has its disadvantages:

While most 32-bit applications have no problem in a 64-bit environment, utilities--which tend to work close to the OS's core--are seldom as versatile. For instance, a program that inserts itself into Windows Explorer's context menu has to be rewritten to work with the x64 version of Explorer. More and more utilities today are getting rewritten to work properly in Windows x64.

Another problem: Early, 16-bit Windows (and DOS) programs, written to be compatible with pre-Windows 95 Microsoft operating systems, will not work at all in the 64-bit environment. (They will work in a 32-bit version of Windows running on 64-bit hardware.) That's significant from a historical point of view--for the first time, we have Windows operating systems that won't run the original, IBM-PC version of VisiCalc.