1. Explanation
The installed QQ software is saved in the hard disk, double-click the QQ icon, the operating system will know to run this software, it will find the installed QQ software in the hard disk, and save the data (the installed software is essentially a collection of many data) copied to memory.
#Double-click the QQ icon, this operation is equivalent to a request, passed to the API function of the system;
#QQ does not run in the hard disk, but in the memory, because the reading and writing speed of the memory is much faster than that of the hard disk.
#Read and write speed: memory > solid state drive > mechanical hard drive.
- The mechanical hard disk relies on the motor to drive the platter to rotate to read and write data;
- Memory sticks read and write data through circuits;
- Solid-state drives also read and write data through circuits, but because the control method is different from that of memory, the speed is not as fast as that of memory.
Two, attention
1) Whether running QQ or editing a Word document, the data on the hard disk is first copied to the memory before the CPU can process it. This process is called Load into Memory. To complete this process requires a special program (software), this program is called a loader (Loader).
For example, open a Word document and enter some text. Although what we see is different, the document in the hard disk has not changed. The newly added text is temporarily saved to the memory, and Ctrl+S will save it to the hard disk. Because data is lost when the memory is powered off, if you shut down the Word document after editing it and forget to save it, you will never be able to retrieve the content.
3) If we run more programs, the space occupied will exceed the memory (memory stick) capacity.
For example, the memory capacity of the computer is 2G, but 10 programs are running, and these 10 programs occupy a total of 3G space, which means that it is necessary to copy 3G data from the hard disk to the memory, which is obviously impossible.
==> The Operating System (OS) solves this problem for us: when the space required for the program to run is greater than the memory capacity, the temporarily unused data in the memory will be written back to the hard disk; read it in and write another part of the unused data to the hard disk. In this way, a part of the hard disk space will be used to store temporarily unused data in memory. This part of the space is called virtual memory (Virtual Memory).
4) The read and write speed of the hard disk is much slower than that of the memory, and it will take a lot of time to exchange data repeatedly, so if your memory is too small, it will seriously affect the running speed of the computer, and even "stuck" phenomenon, even if the CPU is strong, There won't be a big change.
#How to pass what the software has to do to the system? Reference: http://www.cnblogs.com/volcao/p/8908141.html