Virtual computer memory

Those computer users who are luckyfind the glory of the heyday of systems based on 8086-compatible processors, know very well how important the amount of installed memory was at that time. The account went literally to kilobytes: in order to exceed the base 640 kb and reach the "fantastic" 736 kb, a special external expansion module was purchased, representing a weighty board in a relatively large package. However, computer technology quickly evolved and soon a psychological barrier of 1 megabyte was passed. Modules of RAM became much more compact, in addition, there were processors that use it in full. Do not lag behind and applications. A significant event was the release of Windows version 3, which used virtual memory. However, these were only timid steps in the direction that would later become the standard for all operating systems.

What is virtual memory? Imagine two identical computers running Windows 3, only one has 1 MB of memory, and in the other - 2 MB. Selecting software applications on the basis of volume - is to condemn programmers to hard labor, because they will have to optimize their products under 1, 2, etc. megabyte. To create a program designed for a standard minimum of 640 KB means to abandon some of the possibilities by "driving" the application into the framework. And to focus on 2 MB - means to lose potential buyers who have only 1 MB of computers. This was understood in Microsoft, so a mechanism called "virtual memory" was proposed. Programmers now do not need to know how much is installed in each computer. Of course, some limitations, however, are taken into account, but in general, the operating system took care of how to "make friends" with the resource-demanding application and components of the computer. Of course, no miracles happen in this case. The very principle of work is extremely simple.

Take for example the case when on a computer with1 MB is launched application developed under 2 MB. Part of the volume is taken by the system itself, so only 500 kb (conditionally) is available from 1 MB. Run the application. If virtual memory is not enabled or disabled, then the program takes up all 500 KB and stops working, giving a message about the error that occurred. But everything is completely different if the mechanism is turned on: the 500 KB are occupied, if the next memory request occurs, the data block is written to a special file on the disk, freeing up the volume in the RAM. For the application, the mechanism is "transparent". In fact, virtual memory is part of the operational memory, but it is not located on the chips, but on the disk. Such a decision proved so successful that work is still under way to improve it. So, in the newest Windows 8, a swapfile was added to the already familiar paging file pagefile, intended only for metro applications.

Sometimes users can see the systemmessage that the virtual memory is running low. How to explain this in the light of all of the above? All the more incomprehensible, given that the free disk space on the hard drive can still remain. One of the most probable reasons for this lies in the incorrect settings of the virtual memory mechanism. Although by default the system selects the automatic control mode for the size of the paging file, manual adjustment is possible with the indication of rigid frames. Whether you need to do this or not - each user decides on their own, but if an error occurs due to lack of volume, you will have to raise the permitted upper limit. This is configured in the speed settings (you can get through the properties of "My Computer" or from the control panel).