NonTrial  | 2007-07-01
How much RAM can a computer have?
The primary benefit of moving to 64-bit is the increase in the maximum allocatable system memory (RAM). Windows XP 32-bit, for example, is restricted to a total of 4 GB, which is, by default, equally divided between Kernel and application usage. Using the /3GB switch in the boot.ini file forces Windows to limit the kernel to the upper 1GB and provides up to 3GB for applications. Windows XP x64 can support much more memory. The theoretical memory limit that a 64-bit computer can address is about 16 exabytes (16 billion gigabytes... wow!), Windows XP x64 is currently limited to 128 GB of physical memory and 16 TB of virtual memory. In the future this limit will be increased, basically because hardware capabilities will improve. However, most motherboards compatible with 64-bit processors do not support anywhere close to the maximum limit, and often retain the 4 GB limit. Even though 32-bit applications can be run transparently, the mixing of the two types of code within the same process is not allowed, and this has generated some problems in the world of software development. A 64-bit application cannot link against a 32-bit library (DLL) and similarly a 32-bit application cannot link against a 64-bit library, no matter the fact that both can run at the same time on the same system (64 bit one). This may lead to the need for library developers to provide both 32- and 64-bit binary versions of their libraries, mostly meaning two different versions of the same product, one built for the 32 bit version, one built for the 64 bit. Windows XP x64 Edition includes both 32- and 64-bit versions of Internet Explorer, in order for the third-party browser plugins or ActiveX controls to work on the 64 bit. For the media consumers, there should be noted that older 32-bit drivers and services are not supported by 64-bit Windows, but video and audio codecs such as XviD or OggDS (which are in fact 32-bit DLLs), are supported as long as the media player that uses them is 32-bit as well. So, when the motherboard that can sustain 16 gb of RAM inside the computer, rest assured, I will also switch to the 64 bit computer.