Now we will try to find out what RAM (random access memory) is, and also consider the main types of modern, and not very, computer RAM.

Random Access Memory (RAM) - a part of a computer system that temporarily stores data and instructions necessary for the processor to perform various operations. Data transfer to RAM processor is made directly, or through ultra-fast memory. In simpler terms, these are the elements of the “stuffing” of the system unit, which serve to store programs launched by the user, and to provide the processor with quick access to them. Now let's go directly to the types of memory. PC RAM can be divided into two types: SRAM (static type) and DRAM (dynamic type). Below is more about each of them:

(Dynamic Random Access Memory) - a dynamic type of memory, this is the very rectangular strips of RAM that we insert into the slots on the motherboard. To store a bit or trit bit, a circuit is used that consists of one capacitor and one transistor (in some variations, there are two capacitors). This type of memory solves, firstly, the problem of high cost (one capacitor and one transistor are cheaper than several transistors) and, secondly, compactness (where one trigger, that is, one bit, is placed in SRAM, eight capacitors and transistors can fit), this type of memory has a number of disadvantages:

• such memory is slower than SRAM memory, which means that the access time to the information it contains also increases;
• the second disadvantage is the discharge of the capacitors that make up the DRAM: in order not to lose the contents of the memory, the charge of the capacitors must be "regenerated" after a certain time interval. Regeneration is performed by the central microprocessor or memory controller. Since all memory operations are periodically suspended to regenerate memory, the performance of this type of RAM is significantly reduced.

SRAM (Static Random Access Memory) - a static type of memory, which is usually based on triggers, this type of RAM does not need regeneration and the advantage of this type of memory is speed. Since the flip-flops are assembled on gates, and the gate delay time is very small, the switching of the trigger state is very fast, but the disadvantage of this type of memory is its high cost. Also, a group of transistors included in the trigger takes up much more space than capacitors, so the amount of such memory is limited. This type of memory is used to organize ultra-fast memory ( memory cache), the cache, in turn, is used in processors, hard drives, and in other devices.

The most important characteristic on which memory performance depends is its bandwidth. Modern memory has a bus width of 64 bits (or 8 bytes), so the bandwidth of DDR800 memory is 800 MHz x 8 Bytes = 6400 MB per second. Hence, another designation of this type of memory follows - PC6400. Recently, two-channel and three-channel memory connections are often used, in which its bandwidth doubles and triples, respectively. Thus, in the case of two DDR800 modules, we will get the maximum possible data exchange rate of 6.4 GB / s and 12.8 GB / s, but this is just in theory, in practice, things are different and the gain from such modes is quite insignificant.

Now let's talk more about the types of dynamic RAM:

DDR- used in very old systems and due to its antiquity has a number of shortcomings in the structure of the modules, and has a low data transfer rate.

DDR2- this type of memory is gradually losing relevance these days, but is still used by many computers. The data transfer rate of DDR2 is an order of magnitude higher than that of DDR (the slowest DDR2 model is equal in speed to the fastest DDR model).

DDR3- the most common type of memory today. If we take into account the data transfer rate, it is again higher than the previous generation memory (The slowest DDR3 model in terms of data transfer rate is equal to the fastest DDR2 model).

DDR4- a new type of RAM, which differs from previous generations in higher frequency characteristics and low voltage. Will support frequencies from 2133 to 4266 MHz.

Table 1: Specifications of RAM according to JEDEC standards

The maximum memory performance is also affected by such important parameters as "memory timings".

Timing- this is the delay between the individual operations performed by the controller when accessing the memory. If we consider the composition of memory, we get: its entire space is represented as cells (rectangles), which consist of a certain number of rows and columns. One such "rectangle" is called a page, and the collection of pages is called a bank. To access a cell, the controller sets the bank number, page number in it, row number and column number, all requests take time, in addition, a rather large cost is spent on opening and closing the bank after the read / write operation itself. Each action takes time, it is called timing.

If your computer has become slower, additional RAM may be a solution to this problem. In this case, you need to figure out what RAM is and why it is needed, find out its parameters, and also read the recommendations for installing and replacing this module.

What is RAM?

RAM stands for Random Access Memory. It is also called:

1. RAM (Random Access Memory);
2. random access memory;
3. Or just RAM.

Photo: Random Access Memory

RAM is a computer's volatile memory that has random access. During the operation of the computer, it is there that all intermediate, input and output data that the processor processes are stored. All data on RAM can be accessed and will only be saved when the device is powered on. Even with a short power outage, information can be distorted or completely destroyed.

Data is exchanged between Random Access Memory and the processor:

• directly;
• through registers in the ALU;
• through the cache.

OP is:

RAM usage

Operating systems for processing information, as well as storing data that are often used, use RAM. If modern devices did not have Random Access Memory, then all operations would be much slower, since it would take much more time to read information from a permanent memory source.

Also, multi-threading would be impossible. Thanks to the presence of OP, all applications and programs start and work faster. At the same time, nothing makes it difficult to process all the data that is in the queue. Some operating systems, such as Windows 7, have the ability to store files, applications, and other information that the user uses frequently in memory.

Thus, there is no need to waste time while they start to boot from disk, as the process will begin immediately.

As a rule, because of this, Random Access Memory will be constantly loaded by more than 50%. This information can be viewed in the task manager. Data tends to accumulate and those applications that are used less often will be replaced by more necessary ones.

Currently, the most common is dynamic random access memory (DRAM). It is used in many devices. At the same time, it is relatively inexpensive, but it is slower than static (SRAM).

SRAM has found its application in controllers and video chips, and is also used in processor cache memory. This memory has a higher speed, but it takes up a lot of chip space. In turn, manufacturers decided that volume is much more important than accelerated work, so DRAM is used in computer peripherals. In addition, dynamic memory is much cheaper than static memory. At the same time, it has a high density. Due to this, more memory cells are placed on exactly the same silicon crystal. The only downside is that it's not as fast as SRAM.

It should be borne in mind that all the information contained in the OP can only be accessed when the device is turned on. After the user exits the program, all data will be deleted. Therefore, before exiting the application, you must save any changes or additions that have been made.

OP consists of several cells. This is where all the data is located. With each saved change, last information is deleted and a new one is written in its place. The number of cells depends on the amount of Random Access Memory. The larger this volume, the higher the performance of the entire system.

To find out the computer's RAM, you must perform the following steps:

• for Windows XP:

1. hover over the shortcut "My Computer";
2. then you need to press the right mouse button;
3. select "Properties";
4. go to the "General" tab;

• for Windows 7:

Install

Additional OP will help to significantly improve the performance of the device. It can be installed on both a desktop computer and a laptop.

Installing RAM on a computer

First you need to find out what type of OP is required. Its appearance depends on the motherboard. In order to find out which type is compatible with the motherboard, you should check the documents for the device or visit the manufacturer's website. When choosing RAM, it is recommended to purchase 2 or 4 modules. Thus, if you need 8 GB of RAM, then it is better to buy 2 x 4 GB or 4 x 2 GB. At the same time, it is worth paying attention to their throughput and speed. All data must be the same. Otherwise, the system will tune to the most minimal parameters. This may result in performance degradation.

Photo: RAM installed

To install RAM, follow these recommendations:

1. you need to disconnect the monitor, mouse, printer and keyboard from the device;
2. make sure that there is no static charge;
3. remove the old modules - for this you need to open the clamps located on both sides and remove the module;

Important! The new OP module should be held in such a way that it does not touch the chips that are on the side and bottom contacts.

1. RAM must be inserted in such a way that the groove exactly matches the protrusion located in the connector;
2. press on the board and fix it, while the clamps should close;
3. build a computer;
4. turn on the device;
5. check for OP.

Installing RAM on a laptop

For this you need:

1. correctly determine the type of OP;
2. eliminate static charge;
3. disconnect the laptop from the power supply and remove the battery;
4. remove the desired panel on the bottom surface of the laptop;

Important! Most laptops do not require paired modules.

Type and volume

Currently, there are several types of OP. It:

• DDRRAM;
• DDR2 RAM;
• DDR3 RAM.

They differ from each other in the design of the bar, as well as in performance.

Important! It is worth noting that the modules are completely incompatible with each other, as they have different connectors for mounting.

Most modern laptops have DDR2 or DDR3 OP installed. Legacy models work with DDR. The amount of RAM directly affects the speed and performance of the computer.

Now on the market there are modules with a volume of:

1. 512 MB;
2. 1 GB;
3. 2 GB;
4. 4 GB;
5. 8 GB

Before purchasing additional modules it is worth considering that a 32-bit operating system will only be able to recognize 4 GB. Therefore, there is no need to spend money on boards with a large volume due to the fact that it will not be used anyway. But if the operating system has 64 bits, you can install 8, 16 or even 32 gigabytes of memory for it.

Video: increase RAM

Frequency and other parameters

Among the main parameters of Random Access Memory, the following should be highlighted:

1. DDR - 2.2 Volts;
2. DDR2 - 1.8 Volts;
3. DDR3 - 1.65 Volts.

• module manufacturer. Preference should be given to well-known brands and models that have the most positive reviews. This will help eliminate the possibility of buying a defective part, and the warranty period will be longer.

What does RAM look like in a computer?

The OP of the computer is a plate consisting of several layers of textolite. It has:

• printed circuit board;
• soldered memory chips;
• there is also a special connector for connection.

Where is RAM located? OP is located directly on the motherboard.

There are slots for modules, usually 2 or 4 of them. They are located next to the processor.

Photo: storage device on the motherboard

OP for PC and laptops

RAM designed for a laptop has several differences from the RAM that is used in a PC, namely:

1. the modules differ in their size - the plate for a laptop is much shorter than the standard one for a computer;
2. the bar also features unique connectors.

Therefore, the module used for PC cannot be installed in a laptop.

RAM is one of the most important parts in a computer. It is responsible for the speed of launching various programs and applications, as well as for the temporary storage of information. In addition, it is used to connect external devices and hard drive with processor.

Tyumen State Oil and Gas University

Department of Automation and Control

Guidelines for laboratory work No. 1.4

"RAM"

Tyumen 2005

Objective : Learning the types of RAM.

RAM: basic concepts

RAM This is the work area for the computer's processor. It stores programs and data during operation. RAM is often thought of as temporary storage because data and programs are stored in it only when the computer is turned on or until the reset button is pressed. Before turning off or pressing the reset button, all data that has been changed during operation must be saved to a storage device that can store information permanently (usually a hard disk). When the power is turned on again, the saved information can be loaded into memory again.

RAM devices are sometimes called random access storage devices. This means that access to data stored in RAM does not depend on the order of their location in it. When talking about computer memory, they usually mean RAM, primarily memory chips or modules that store active programs and data used by the processor. However, sometimes the term memory also applies to external storage devices such as disks and tape drives.

Over the years, the definition of RAM (Random Access Memory) has evolved from a common abbreviation to a term that refers to the main working memory space created by Dynamic RAM (DRAM) chips and used by the processor to execute programs. One of the properties of DRAM chips (and, consequently, RAM in general) is dynamic data storage, which means, firstly, the possibility of repeatedly writing information to RAM, and secondly, the need for constant updating of data (i.e., essentially overwriting them) approximately every 15 ms. There is also the so-called static random access memory (Static RAM - SRAM), which does not require constant updating of data. It should be noted that data is stored in RAM only when the power is on.

Term RAM often refers not only to the chips that make up the memory devices in the system, but also includes concepts such as logical mapping and placement. Logical mapping is a way of representing memory addresses on actually installed chips. Location is the location of information (data and commands) of a certain type at specific addresses in the system's memory.

While a program is executing, its data is stored in RAM. Random access memory (RAM) chips are sometimes referred to as volatile memory: after the computer is turned off, the data stored in them will be lost if they were not previously stored on a disk or other external memory device. To avoid this, some applications automatically back up data.

The files of a computer program, when it is launched, are loaded into RAM, in which they are stored while working with the specified program. The processor executes the software-implemented instructions contained in the memory and stores their results.

RAM stores the codes of the keys pressed when working with text editor, as well as the magnitude of mathematical operations. When you execute the Save command, the contents of RAM are saved as a file on your hard drive.

The physical RAM in a system is a set of chips or modules containing chips that are usually connected to the system board. These chips or modules may have different characteristics and must be compatible with the system in which they are installed in order to function correctly.

There are three main types of storage devices used in modern computers.

ROM (read Only Memory). Read-only memory is a ROM that is not capable of performing a data write operation.

DRAM (dynamic Random Access Memory). Dynamic memory with random access order.

SRAM(Static RAM). Static RAM.

RAM (RAM, RAM - Random Access Memory- eng.) - relatively fast the volatile random-access memory of a computer, in which most of the data exchange operations between devices take place. It is volatile, that is, when the power is turned off, all data on it is erased.

RAM is a repository of all information flows that need to be processed by the processor or they wait in RAM for their turn. All devices communicate with RAM through the system tire, and with it, in turn, are exchanged through the cache or directly.

Random Access Memory- memory with random (direct) access.

This means that, if necessary, the memory can directly refer to one required block, without affecting while the rest. Speed random access does not change from location necessary information which is a huge plus.

RAM, compares favorably from volatile memory, with almost zero impact of the number of read/write operations on service life and durability. Subject to all the subtleties in production, RAM very rarely fails. In most cases, damaged memory begins to make mistakes that lead to system crash or instability of many computer devices.

RAM can be either a separate module that can be changed and additional ones added (for example, a computer), as well as a separate unit of a device or chip (as in or the simplest SoC).

RAM usage .

Modern operating systems actively use RAM to store and process important and frequently used data in it. If RAM were not used in electronic devices, then all operations would be much slower and for reading from a permanent memory source ( ROM), would require a significant more time. Yes and more or less multithreaded processing would be nearly impossible.

RAM usage, allows applications to run and run faster. Data can be processed and wait in line without hindrance thanks to addressability(all machine words have their own addresses).

Operating system Windows 7 for example, it can store frequently used files, programs, and other data in memory. This allows you to start programs not to wait until they are loaded from a slower disk, but immediately begin execution. Therefore, do not be afraid if the task manager shows that your RAM loaded with more than 50% . When you run an application that requires large memory resources, older data will be forced out of it in favor of more necessary ones.

Most devices use dynamic random access memory DRAM (Dynamic Random Access Memory ), which has a low price but is slower static SRAM (Static Ramdom Access Memory ). More expensive static memory has found its way into fast processors and controllers. Due to the fact that static memory takes up much more space on a chip than dynamic memory, in times of rapid development of computer peripherals and operating systems, manufacturers went for a larger volume rather than a higher speed path, which was more justified.

The most popular and productive memory in personal computers, since the 2000s, has rightfully become DDR SDRAM.

Remarkably, there is no backward compatibility support for any of the versions. The reason lies in the different frequencies and principles of operation of memory controllers for different versions.

Therefore, it is impossible to insert, for example, memory DDR3 into the memory slot DDR2, thanks to a notch elsewhere.

Subsequent versions DDR2 SDRAM and DDR3 SDRAM, received a significant jump in the growth of the effective frequency. But the real increase in speed was only when switching from DDR1 on the DDR2 by keeping the delay time at an acceptable level, with a significant increase in the frequency of work. DDR3 the memory cannot boast of the same and with a doubling of the frequency, the delays also almost double. Accordingly, there is no gain in speed in real conditions. But there is a significant plus from the transition to new versions, which always works - this is a decrease energy consumption and heat dissipation, which favorably affects the stability and the possibility of overclocking. Modern versions DDR3 rarely get hotter 50 degrees Celsius.

My respect, dear readers, friends, enemies and other personalities!

Today I want to talk with you about such an important and useful thing as RAM, in connection with which two articles have been published at once, one of which talks about memory in general (tobish below in the text), and the other (in fact, the article is located directly below this one, just published separately).

Initially, it was one material, but in order not to make another multi-letter page-sheet, and simply for reasons of separation and systematization of articles, it was decided to split them into two.

Since the crushing process was carried out on the fly and almost at the last moment, there may be some flaws in the text that you should not be afraid of, but you can report them in the comments in order, in fact, to correct them on the fly as well.

Well, now, let's get started.

introductory

Before each user sooner or later (or never) the question arises of upgrading his faithful "iron horse". Some immediately change the "head" - the processor, others - conjure over the video card, however, the easiest and cheapest way is to increase the amount of RAM.

Why the easiest?

Yes, because it does not require special knowledge of the technical part, the installation takes little time and creates almost no difficulties (and it is also the least expensive of all that I know).

So, in order to learn a little more about such a simple and at the same time effective upgrade tool as RAM (hereinafter referred to as OP), for this we turn to our dear theory.

General

RAM (Random Access Memory), also known as RAM ("Random Access Memory" - random access memory), is an area of ​​​​temporary data storage, with the help of which the functioning of software. Physically, RAM in a system is a set of chips or modules (containing chips) that are usually connected to the system board.

During operation, the memory acts as a temporary buffer (it stores data and running programs) between disk drives and the processor, due to the significantly faster read and write data.

Note.
Very beginners often confuse RAM with hard disk memory (ROM - Read Only Memory), which is not necessary, because. it's perfect different types memory. RAM (by type it is dynamic - Dynamic RAM), in contrast to the constant - volatile, i.e. it requires power to store data, and when it is turned off (switching off the computer), the data is deleted. An example of non-volatile ROM memory is flash memory, in which electricity is only used for writing and reading, while no power source is needed to store data itself.

In its structure, memory resembles a honeycomb; consists of cells, each of which is designed to store honey a certain amount of data, usually one or four bits. Each cell of this has its own unique "home" address, which is divided into two components - the address of the horizontal row (Row) and the vertical column (Column).

Cells are capacitors capable of storing electrical charge. With the help of special amplifiers, analog signals are converted into digital ones, which in turn form data.

To transfer the address of the row to the memory chip, a certain signal is used, which is called RAS ( Row address strobe), and for the column address - the signal CAS ( Column address strobe).

How does RAM work?

The work of RAM is directly related to the work of the processor and external devices of the computer, since it is the latter that “trust” their information to it. Thus, the data first gets from the hard disk (or other media) to the RAM itself and only then is processed by the central processor (see image).

Data exchange between the processor and memory can occur directly, but more often it still happens with the participation of cache memory.

Cache memory is a place of temporary storage of the most frequently requested information and is a relatively small area of ​​fast local memory. Its use can significantly reduce the time of information delivery to the processor registers, since the speed of external media (RAM and disk subsystem) is much worse than the processor one. As a result, forced downtime of the processor is reduced, and often completely eliminated, which increases the overall performance of the system.

The RAM is controlled by the controller, which is located in the chipset of the motherboard, or rather in that part of it called the North Bridge (North Bridge) - it connects the CPU (processor) to nodes using high-performance buses: RAM, graphics controller (see image) .

Note.
It is important to understand that if during the operation of the RAM data is written to any cell, then its contents, which were before the arrival of new information, will be irretrievably lost. Those. at the command of the processor, data is written to the specified cell, while erasing what was previously written there.

Let's consider another important aspect the work of the RAM is its division into several sections using special software (software) that is supported by operating systems.

Now you will understand what I mean.

More

The fact is that modern RAM devices are large enough (hello two thousandth, when 32 MB was enough) so that data from several simultaneously working tasks can be placed in it. The processor can also handle multiple tasks at the same time. This circumstance contributed to the development of the so-called dynamic memory allocation system, when dynamic (variable in size and location) sections of RAM are allocated for each task processed by the processor.

The dynamic nature of the work allows you to manage the available memory more economically, timely "withdrawing" extra memory sections from some tasks and "adding" additional sections to others (depending on their importance, the amount of information being processed, the urgency of execution, etc.). The operating system is responsible for the "correct" dynamic allocation of memory in a PC, while the application software is responsible for the "correct" use of memory.

It is quite obvious that application programs must be able to work under the control of the operating system, otherwise the latter will not be able to allocate RAM to such a program or it will not be able to “correctly” work within the allocated memory. That is why it is not always possible to run under a modern operating system, previously written programs that worked under obsolete systems, for example, under early versions of Windows (98 for example).

Also (for general development) you should know that memory support depends on the bit depth of the system, for example, the Windows 7 operating system, with a bit depth of 64 bits, supports up to 192 GB of memory (the younger 32-bit colleague "sees" no more than 4 GB). However, if this is not enough for you, please, 128-bit claims support for truly colossal volumes - I don’t even dare to voice this figure. A little more about bit depth.

Why is this RAM needed?

As we already know, the exchange of data between the processor and memory occurs most often with the participation of cache memory. In turn, it is controlled by a special controller, which, analyzing the program being executed, tries to foresee what data and commands are most likely to be needed by the processor in the near future, and pumps them up, i.e. the cache controller loads the necessary data from the RAM into the cache memory, and returns, when necessary, the data modified by the processor to the RAM.

After the processor, RAM can be considered the fastest device. Therefore, the main data exchange occurs between these two devices. All information in a personal computer is stored on a hard disk. When the computer is turned on, drivers are written to the RAM from the screw, special programs and elements of the operating system. Then those programs are written there - applications that we will run, when the latter are closed, they will be erased from it.

The data written in the RAM is transferred to the CPU (it is also the processor mentioned more than once, it is also the Central Processing Unit), processed there and written back. And so constantly: they gave the processor a command to take the bits to such and such addresses (such as: process them and return them to their place or write them to a new one) - he did just that (see image).

All this is good as long as there are enough memory cells (1). And if not?

Then the swap file (2) comes into play. This file is located on the hard disk and everything that does not fit into the RAM cells is written there. Since the speed of the screw is much lower than RAM, the operation of the paging file greatly slows down the system. In addition, it reduces the durability of the hard drive itself. But that's a completely different story.

Note.
All modern processors have a cache (cache) - an array of ultra-fast RAM, which is a buffer between the relatively slow system memory controller and the processor. This buffer stores the blocks of data that the CPU is currently working with, which significantly reduces the number of processor accesses to extremely slow (compared to the speed of the processor) system memory.

However, the cache memory is ineffective when working with large amounts of data (video, sound, graphics, archives), because such files simply do not fit there, so you have to access the RAM all the time, or the HDD (which also has its own cache) .

Module layout

By the way, let's look at what the module itself consists of (what elements).

Since almost all memory modules consist of the same structural elements, for clarity we will take the SD-RAM standard (for desktop computers). The image specifically shows a different design of these (so that you know not only the "template" version of the module, but also a very "exotic").

So, SD-RAM standard modules (1): DDR (1.1); DDR2 (1.2 ).

Description:

1. Memory chips (microcircuits)
2. SPD (Serial Presence Detect) is a non-volatile memory chip that stores the basic settings of any module. During system startup, the motherboard BIOS reads the information displayed in the SPD and sets the appropriate timings and RAM frequency;
3. "Key" - a special slot on the board, by which you can determine the type of module. Mechanically prevents incorrect installation of dies in slots intended for RAM;
4. SMD components of modules (resistors, capacitors). Provide electrical decoupling of signal circuits and power management of chips;
5. Manufacturer's stickers - indicate the memory standard, nominal frequency and base timings;
6. RSV - printed circuit board. The remaining components of the module are soldered on it. The overclocking result often depends on the quality: the same chips can behave differently on different boards.

Afterword

Actually, these are the basics of the basics and the basic basis, and therefore, I hope that the article was interesting to you both from the point of view of broadening your horizons, and as a brick in personal knowledge about a personal computer :).

Everything on the sim. As always, if you have any questions, comments, additions, etc., then you can safely run to the comments below. And yes, don't forget to read the material.