64 bit & 32 bit Operating Systems Explained

You have probably come across the term 32 bit and 64 bit operating systems when either shopping for a new desktop or laptop machine or when looking up your machines specifications. Most people don't know what all these means and what effect having a 32 or 64 bit system has.

Most computers these days come pre-installed with 64 bit version of the operating system, this can also be referred to as x64 systems while the 32 bit versions are also referred to as x86 systems.


Checking which version you have
To figure out which version of Windows you are running, just head into the System properties in Control Panel, or you can take the easy route and right-click on your Computer icon in the start menu or desktop, and choose Properties from the menu. Windows 7 or Vista users will be able to check the System type in the list, while the few XP users with 64-bit will see it on the dialog.

Keep in mind that your CPU must support 64-bit in order to be running a 64-bit operating system—if you're running a modern CPU you should be fine, but some of the budget PCs don't include a 64-bit processor.


Where the difference comes in
In any 32-bit operating system, you are limited to 4096 MB of RAM simply because the size of a 32-bit value will not allow any more. On a 32-bit system, each process is given 4 GB of virtual memory to play with, which is separated into 2 GB of user space that the application can actually use at a time.
Not only does 32-bit have a hard limit for the amount of memory it can address, there's also another problem: your devices, like your video card and motherboard BIOS take up room in that same 4 GB space, which means the underlying operating system gets access to even less of your RAM.
While 32 bits of information can only access 4 GB of RAM, a 64-bit machine can access 17.2 BILLION gigabytes of system memory, banishing any limits far into the future. This also means that your video cards and other devices will not be stealing usable memory space from the operating system. Windows 64-bit Home editions are still limited to 16 GB of RAM for licensing reasons, but the Professional and Ultimate versions can use up to 192 GB of RAM.
The per-process limit is also greatly increased—on 64-bit Windows, instead of a 2 GB limit, each application has access to 8 TB of virtual memory without any special API, a huge factor when you consider applications like video editing or virtual machines that may need to use enormous amounts of RAM.


Do 32-bit Applications Work on 64-Bit?
The vast majority of your 32-bit applications will continue to work just fine on 64-bit Windows, which includes a compatibility layer called WoW64, which actually switches the processor back and forth between 32-bit and 64-bit modes depending on which thread needs to execute making 32-bit software run smoothly even in the 64-bit environment.
There are some exceptions to that rule, however: 32-bit device drivers and low-level system applications like Antivirus, shell extensions that plug into Windows, and some media applications simply won't work without a 64-bit equivalent.


What should you get?
If you are ordering a new PC with 4 GB or more of RAM, you should probably be running a 64-bit version of Windows so you can use all of the available memory, especially if you want a machine with a large video card and RAM for some serious gaming or video editing work.

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