32 Bit Vs. 64 Bit Linuxby Chris Hoffman
The majority of new computers support 64-bit software, but software incompatibility has held 64-bit operating systems back. Now 64-bit operating systems are becoming more widely used, with even Windows 7 being embraced in 64-bit form. 64-bit operating systems are better able to utilize larger amounts of RAM and are faster at certain types of processor-intensive tasks, but there are some lingering issues around compatibility with 32-bit third-party software, particularly Web browser plug-ins.
64-bit operating systems require 64-bit processors, whereas 32-bit operating systems run on both, 64-bit processors are backwards compatible with 32-bit software. New processors from AMD and Intel released in the past few years support 64-bit and are advertised prominently as 64-bit processors. Recently purchased computers are generally 64-bit capable. Consult your computer's documentation for more information.
64-bit Linux operating systems are capable of accessing more than four gigabytes of RAM memory. This is a concern with newer computers including more than four gigabytes of RAM. While 32-bit operating systems have implemented a solution known as "Physical Address Extension," or PAE, that allows them to access up to 64 gigabytes of RAM, the RAM above the four gigabyte point functions slower when accessed with PAE.
CPU-intensive tasks such as encoding video and audio files and crunching numbers perform faster on 64-bit processors if the software doing the number-crunching is compiled for 64-bit and properly coded to take advantage of the improvements. Accessing memory above four gigabytes of RAM is always faster. Users won't generally see a performance difference with general desktop usage, but certain specific tasks perform noticeably faster.
If you're not sure whether your currently installed version of Linux is 32-bit or 64-bit, check which it is with a single command. Open a Terminal by clicking "Applications," "Accessories" or "System Tools" and "Terminal." Type "uname -m" into the Terminal window and press "Enter." If the output is "i386" or "i686," you're using a 32-bit version of Linux. If the output is "x86_64," you're using a 64-bit version.
The majority of Linux applications are compatible with 64-bit. Since most Linux applications are open-source software, they are recompiled by each distribution in 64-bit form. Software incompatibility is only a concern with third-party, closed-source software. Many older closed-source games, for example, are only available as 32-bit software. Luckily, 64-bit operating systems are backwards compatible and run 32-bit software alongside 64-bit software. Depending on your Linux distribution, compatibility libraries are included with the default installation or must be installed afterward; consult your distribution's documentation for more information.
Web Browser Plug-in Compatibility
The greatest software incompatibility issue with 64-bit Linux distributions is Web browser-plug-ins. Web browsers included with 64-bit Linux distributions are 64-bit software, and thus can only load 64-bit Web browser plug-ins. Unfortunately, most commonly used Web browser plug-ins are only available as 32-bit software. Adobe Flash does not support 64-bit Linux, nor does Sun's Java browser plug-in. Many users install 32-bit Web browsers so that they can use these browser plug-ins. Many Linux distributions also include NSPluginWrapper, a compatibility layer that allows plug-ins such as Adobe Flash to work in 64-bit Web browsers. However, this potentially introduces instability.
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