What is computer memory and what is it for?
Gone are the days when the computer was considered exclusively a toy for particularly wealthy people. Today, it is a common work tool that almost everyone faces in everyday life or at work every day.
Unfortunately, not everyone has at least an initial level of computer literacy. This is especially pronounced at the moment when you need to upgrade your PC. Often, people do not even know what RAM is, although in many cases it is its replacement (or increase in volume) that can give the old computer noticeably more "agility". And therefore in this article we will write down what this component is responsible for, how to choose it, and also touch on some other nuances.
So what is RAM? In the literature, it is denoted by the abbreviation of RAM (random access memory), more often the English version - RAM.This component is necessary for the temporary storage of data, which ensures the normal functioning of the software. Typically, its chips are connected to the motherboard through the appropriate connectors, but often they are simply unsoldered on it.
In general, the main task of the RAM is to be a buffer between the processor and the hard disk while the computer is running, retaining all the “intermediate” data and contributing to the high speed of the system (Intel RAM is especially good in this respect).
Often, newbies do not at all make a distinction between RAM and permanent (that is, hard disk). You need to clearly understand that the RAM is volatile, all data from its microcircuits are deleted when the computer is turned off. It should be noted that this does not happen with hard drives. To some extent, a separate subspecies are flash drives, since there is no energy at all to store the recorded information.
We figured out what RAM is. But how is it arranged and how is it characterized? In fact, the structure of RAM is similar to a set of honeycombs. Each cell stores some amount of data (1-4 bits).Note that each "cell" has its own personal address. It is divided into data on the location of the horizontal construction (Row) and vertical position (Column).
Simply put, each cell is a capacitor that can store an electrical discharge for a certain time. Thanks to special algorithms, the data recorded in this way are converted to a format that the computer can understand. In addition, to transmit the address of a row and / or a vertical column of a cell, a signal of the RAS and CAS type is used, respectively. However, all this refers to such matters, about which the usual user is not necessary to know.
How does all this work?
If you read carefully, you already realized that first the necessary information is downloaded from the hard disk, “stored up” in the RAM modules, and then processed by the central processor. All these devices can exchange data directly, but where it happens more often with the participation of cache memory.
It has both processors and hard drives. Cache is designed to store especially frequently used information. Its presence can significantly accelerate the speed of the entire system as a whole,since the speed of the hard disk and RAM is much lower than that of the CPU itself. If the volume of this drive is sufficient, it is possible to completely get rid of the forced downtime and inactivity of the equipment.
The very same RAM is controlled by a separate controller, which is located on the north bridge of the motherboard. In addition, it also depends on the connection of the CPU to other devices that use "fat" tires for data transfer (all the same RAM, graphics subsystem).
When the RAM is working and information is being recorded in a cell, all the data that was there before will be lost irretrievably. It should be noted that modern operating systems support partitioning of RAM into several sections at once, this provides a markedly increased speed of work. How does all this function?
The fact is that modern RAM devices have a large volume, and therefore they can contain data from several processes working simultaneously.Of course, the CPU is also capable of processing several hundred tasks at a time. To ensure that the normal operation of the computer, a system for dynamic memory allocation was developed. In this case, for each task that is currently “under consideration” of the central processor, its own dynamically changeable block of RAM is allocated.
What are such difficulties for?
Such a unit helps to manage the available RAM much more economically, since the most important and priority tasks are allocated more space. It should be noted that truly high-quality dynamic distribution is available only to users of the latest operating system versions.
In addition, the old distribution methods used in the days of Windows 98 or earlier systems make the programs of those years completely inoperative on modern versions of the OS. Even if you have “on board” RAM of gigabyte 4, the RAM of the new generation simply will not understand the old instructions.
Possible modes of operation
Note that RAM can operate in the following modes:
- Single chanell.Single channel, asymmetric mode. It is included in two cases: when the system has only one memory plate, or if the user has installed several chips from different manufacturers, differing from each other in their parameters. It is important to note that the system in the second case will focus on the weakest RAM module, operating at its frequency.
- Dual Mode. Two-channel, symmetric mode. To do this, exactly the same rams of RAM are installed in two slots, as a result of which the data transfer rate can increase significantly. Accordingly, to activate this mode, the chip must be placed in 1 and 3 and / or 2 and 4 slots. Note that the 2nd generation RAM (DDR2) can only work in this mode (most often).
- Triple mode. Three-channel mode in recent times is quite rare. In general, it is a variation of the previous mode, but is used only on those motherboards, on which there are three connectors for installing RAM modules. It should be noted that in practice such a mode is very often inferior to the dual-channel version (any test of the RAM will indicate this).
- Flex Mode (flexible).This is a very interesting mode that allows you to "squeeze" the maximum performance from two different memory plates (it is important that they be the same in frequency). The modules are installed in the same manner as the two-channel version.
What happens after turning on the computer?
As we have said, the exchange of information between the most important devices of the computer takes place using the cache memory. It, in turn, is controlled by a special controller and program for RAM. What are they needed for? The fact is that it is these components that determine the priority of tasks, choosing those programs whose information you need to write to the cache, as well as applications that can “get along” with ordinary RAM.
When you turn on the computer, all the necessary data, elements of the operating system itself and programs that should start automatically immediately after the computer starts, are immediately recorded in the RAM from the hard disk. Of course, that before this is carried out a quick test of RAM (to identify the most serious faults). After that, the data is processed by the central processor.The scheme is repeated cyclically, all the time until you turn off the computer.
All is well, but what happens if the amount of RAM installed in the system is not enough for the software and the system to work?
And if the volume is not enough?
It is then that the paging file comes in, with which all users of not very powerful, outdated machines are probably familiar. This file is located on the system hard drive, and there all the data is recorded that banally does not fit the RAM, the price of which is quite high (from one and a half thousand for 2 GB), so many people face this problem.
You yourself can understand that the performance of the entire operating system suffers greatly in this case due to the slow speed of the hard disk. In addition, due to constant calls to the hard drive, the latter wears physically much faster.
On the contrary, when you have a lot of RAM, you can greatly gain in performance. To do this, you need a special program for RAM, which will create a virtual hard disk right in it. It can transfer all applications that require high performance.
Physical selection of memory modules
For general development, it doesn’t hurt to find out which modules the RAM chip consists of. So, here are all its main components:
- Directly blocks of memory.
- SPD is a special non-volatile chip, in which the standard parameters of a specific module are sewn. When the computer is turned on, the motherboard's BIOS reads values from this chip, based on which timings and other important parameters are set. This is especially important if RAM is discussed for a laptop, which can often be in “suspended animation” for days.
- "Key". This is the name of the slot at the bottom of the board, from which you can determine its type (DDR2, DDR3). Its main purpose is that it mechanically prevents the installation of an inappropriate type of RAM for this board.
- SMD components. These include sets of resistors and capacitors. It is not difficult to guess that they are responsible for the power supply and power supply of the memory modules.
- Stickers. These are the basic settings from the manufacturer, which are necessary for the correct operation of some specific components.
- PCB, that is, directly printed circuit board.It is on it that all the above components are unwelded. Not only the speed of the RAM itself, but also the operability of the entire system and computer (so to speak, “maximum” RAM) depends on its quality, the status of the layout of the tracks and processing.
Criteria for memory selection
If you have mastered the previous part, we invite you to read about the criteria for selecting RAM. First of all, you need to pay attention to what type of memory your motherboard supports (DDR1 / 2/3). You can figure it out in three ways:
- Read information from your board manufacturer.
- Open the system unit and see the model name.
- If there are no such possibilities, you can study the manual for your processor: surely all compatible motherboards are listed there, so you can certainly find out the truth.
However, if you have a normal internet connection, you can do even easier: click on the "Run" item in the "Start" menu, and then enter the dxdiag command there. After a while, the diagnostic utility window will appear. The “Computer Model” item is important to you, in which the motherboard model is registered.
Then you should read the information from the processor manufacturer, find your model there and find out which types of RAM are most appropriate for using on a specific computer. In general, after that you can go to the store, where the right RAM is waiting for you. Its price, by the way, is quite high. So, even for a couple of gigabytes on an outdated DDR2 module, you can give up to two thousand rubles. However, DDR3 is still much cheaper.
It should be noted that some confuse the form factor of different types of RAM. So, the memory for a laptop is called SO-DIMM, whereas in desktops full-size DIMM memory is used. As a rule, the first type is also installed in monoblocks and (rarely) in compact PCs. Do not confuse when buying!
This is what RAM is and why it is needed in a computer.