Types of ddr RAM. RAM details


The component market is constantly updated with new developments and innovations with enviable regularity, which is why many users, whose funds clearly do not allow them to acquire new hardware in a timely manner, have doubts about the power and performance of their computer as a whole. At all times, the discussion of a lot of questions on technical forums about the relevance of their components never subside. Moreover, the questions concern not only the processor, video card, but even RAM. However, even despite all the dynamics of the development of computer hardware, the relevance of technologies of previous generations is not lost as quickly. This also applies to components

DDR2 memory: from the first days on the market to the decline of popularity

DDR2 is the second generation of random access memory (from the English Synchronous Dynamic random access memory - SDRAM), or, in a formulation familiar to any user, the next generation of RAM after DDR1, which has become widespread in the segment of personal computers.

Having been developed back in 2003, it has fully gained a foothold in the market. new type I was able to do this only at the end of 2004 - only at that time chipsets with DDR2 support appeared. Actively advertised by marketers, the second generation was presented as an almost twice as powerful alternative.

What is worth highlighting first of all from the differences is the ability to operate at a significantly higher frequency, transmitting data twice in one clock cycle. On the other hand, a standard negative aspect of raising frequencies is an increase in delay time during operation.

Finally, by the mid-2000s, the new type had fundamentally infringed on the position of the previous, first one, and only by 2010 DDR2 was in a meaningful way replaced by the new DDR3.

Device Features

Distributed DDR2 RAM modules (in common parlance, called “dies”) had some distinctive features and varieties. And although the new one was not frankly striking for its time with an abundance of variations, even the external differences immediately caught the eye of any buyer at first glance:

  • Single-sided/double-sided SDRAM module on which chips are located on one or two sides, respectively.
  • DIMM is the current standard form factor for SDRAM (synchronous dynamic random access memory, which is DDR2). Massive use in general-purpose computers began in the late 90s, which was mainly facilitated by the appearance of the Pentium II processor.
  • SO-DIMM is a shortened SDRAM module form factor developed by in a special way For laptop computers. SO-DIMM DDR2 dies for laptops had several significant differences from standard DIMMs. This is a module with smaller physical dimensions, lower power consumption and, as a result, lower performance level compared to a standard DIMM factor. An example of a DDR2 RAM module for a laptop can be seen in the photo below.

In addition to all the above features, we should also note the rather mediocre “shell” of the dies of those times - almost all of them, with rare exceptions, were then represented only by standard boards with microcircuits. Marketing in the computer hardware segment was just beginning to take off, so there were simply no samples on sale with the most common radiators for modern RAM modules. various sizes and design. Until now, they perform primarily a decorative function rather than the task of removing generated heat (which, in principle, is not typical for DDR type RAM).

In the photo below you can see what DDR2-667 RAM modules with a heatsink look like.

Compatibility Key

DDR2 memory, by its design, is extremely important difference from previous DDR - no backward compatibility. In the second-generation samples, the slot in the contact area of ​​the strip with the RAM connector on the motherboard was already located differently, which made it physically impossible to insert a DDR2 stick into a connector designed for DDR without breaking one of the components.

Volume parameter

For serial motherboards (any motherboard for home/office use), the DDR2 standard could offer a maximum capacity of 16 gigabytes. For server solutions, the volume limit reached 32 gigabytes.

It is also worth paying attention to one more technical nuance: the minimum volume of one die is 1 GB. In addition, there are two more variants of DDR2 modules on the market: 2Gb and 8Gb. Thus, in order to get the maximum possible supply of RAM of this standard, the user will have to install two 8 GB sticks or four 4 GB sticks, respectively.

Data transmission frequency

This parameter is responsible for the ability of the memory bus to pass as much as possible more information per unit of time. A higher frequency means more data can be transferred, and here DDR2 memory has significantly outperformed the previous generation, which could operate in the range from 200 to 533 MHz maximum. After all minimum frequency DDR2 strips are 533 MHz, and top-end copies, in turn, could boast of overclocking to 1200 MHz.

However, with the increase in memory frequency, the timings naturally increased, on which memory performance not least depends.

About timings

Timing is the time interval from the moment of requesting data to reading it from RAM. And the more the frequency of the module increased, the longer the RAM needed to complete operations (not to the point of colossal delays, of course).

The parameter is measured in nanoseconds. The most influential factor on performance is latency timing (CAS latency), which in the specifications is designated as CL* (any number can be specified instead of *, and the lower it is, the faster the memory bus will operate). In some cases, the timings of the bars are indicated by a three-character combination (for example, 5-5-5), but the most critical parameter will be the first number - it always indicates memory latency. If the timings are indicated in a four-digit combination, in which the last value is strikingly greater than all the others (for example, 5-5-5-15), then this indicates the duration of the total working cycle in nanoseconds.

An old man who never loses his shape

With its appearance, the second generation caused a lot of noise in computer circles, which ensured its considerable popularity and excellent sales. DDR2, like the generation before it, could transfer data on both slices, but a faster bus with the ability to transfer data significantly increased its performance. Besides positive thing there was also higher energy efficiency - at the level of 1.8 V. And if this hardly had any effect on the overall picture of the computer’s energy consumption, then it had a purely positive effect on the service life (especially with intensive work of the hardware).

However, technologies would cease to be such if they did not develop further. This is exactly what happened with the advent of the next generation DDR3 in 2007, whose task was to gradually but surely oust the aging DDR2 from the market. However, does this “obsolescence” really mean a complete lack of competition with new technology?

One on one with the third generation

In addition to traditional backward incompatibility, DDR3 introduced a number of several technical innovations to RAM standards:

  • The maximum supported volume for serial motherboards increased from 16 to 32 GB (at the same time, one module could reach 16 GB instead of the previous 8).
  • More high frequencies data transmission, the minimum of which is 2133 MHz and the maximum is 2800 MHz.
  • Finally, reduced power consumption is standard for each new generation: 1.5 V versus 1.8 V for the second generation. In addition, two more modifications were developed based on DDR3: DDR3L and LPDDR3, consuming 1.35 V and 1.2 V, respectively.

Along with the new architecture, timings have also increased, but the drop in performance from this is offset by higher operating frequencies.

How the buyer decides

The buyer is not a development engineer; In addition to the technical characteristics, the price of the product itself will be no less important to the buyer.

At the start of sales of a new generation of any computer hardware, its cost will usually be higher. The same new type of RAM initially comes to the market with a very large price difference compared to the previous one.

However, the increase in performance between generations in most applications, if not absent at all, is simply ridiculous, clearly not worthy of large overpayments. The only right moment to switch to a new generation of RAM is the maximum drop in its price tag to the level of the previous one (this always happens in the SDRAM sales segment, it was the case with DDR2 and DDR3, the same thing has now happened in the case of DDR3 and the new DDR4). And only when the price of overpayment between the latest and previous generations is the bare minimum (which is adequate for a small increase in performance), then only in this situation can you think about replacing RAM.

In turn, for owners of computers with DDR2 memory, it is most rational to acquire a new type of RAM only with a thorough upgrade from an appropriate one that supports this newest type, and a new motherboard (and even today it makes sense to upgrade to the level of components that support DDR4 memory: its current price is on par with DDR3, and the increase between the fourth and second generations will be much more noticeable than between the third and second).

Otherwise, if such an upgrade is not planned by the user at all, then it is quite possible to get by with the same DDR2, the price of which is now relatively low. It will only be enough to increase, if necessary, the total amount of RAM with similar modules. The permissible limits of this type of memory, even today, more than cover all the needs of most users (in most cases, installing an additional DDR2 2Gb module will be enough), and the performance lag with the next generations is completely uncritical.

Minimum prices for RAM modules (only samples of proven brands Hynix, Kingston and Samsung are taken into account) may vary depending on the region of residence of the buyer and the store he has chosen.

My respects dear site visitors. In the last article I wrote about. Now, having learned what it is and what and how it serves, many of you are probably thinking about purchasing a more powerful and productive RAM for your computer. After all, increasing computer performance with additional memory RAM is the simplest and cheapest (unlike, for example, a video card) method of upgrading your pet.

And... Here you are standing at the display case with packages of RAMs. There are many of them and they are all different. Questions arise: Which RAM should I choose?How to choose the right RAM and not make a mistake?What if I buy a RAM and then it doesn’t work? These are completely reasonable questions. In this article I will try to answer all these questions. As you already understand, this article will take its rightful place in the series of articles in which I wrote about how to choose the right individual components computer i.e. iron. If you haven't forgotten, it included the following articles:
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This cycle will continue, and in the end you will be able to assemble for yourself a super computer that is perfect in every sense 🙂 (if finances allow, of course :))
In the meantime learning how to choose the right RAM for your computer.
Go!

RAM and its main characteristics.

When choosing RAM for your computer, you should definitely start from your motherboard and processor because RAM modules are installed on the motherboard and it also supports certain types of RAM. This creates a relationship between the motherboard, processor and RAM.

Find out about what RAM does your motherboard and processor support? You can go to the manufacturer’s website, where you need to find the model of your motherboard, as well as find out which processors and RAM it supports. If you don’t do this, it will turn out that you bought a super modern RAM, but it is not compatible with your motherboard and will gather dust somewhere in your closet. Now let's move directly to the main technical characteristics of RAM, which will serve as unique criteria when choosing RAM. These include:

Here I have listed the main characteristics of RAM that you should pay attention to first when purchasing it. Now we will reveal each of them in turn.

Type of RAM.

Today, the most preferred type of memory in the world is memory modules DDR(double data rate). They differ in release time and, of course, technical parameters.

  • DDR or DDR SDRAM(translated from English. Double Data Rate Synchronous Dynamic Random Access Memory - synchronous dynamic memory with random access and double data transfer speed). Modules of this type have 184 contacts on the strip, are powered by a voltage of 2.5 V and have a clock frequency of up to 400 megahertz. This type of RAM is already obsolete and is used only in old motherboards.
  • DDR2- widespread in given time memory type. It has 240 contacts on the printed circuit board (120 on each side). Consumption, unlike DDR1, is reduced to 1.8 V. The clock frequency ranges from 400 MHz to 800 MHz.
  • DDR3- the leader in performance at the time of writing this article. It is no less common than DDR2 and consumes 30-40% less voltage compared to its predecessor (1.5 V). Has a clock frequency of up to 1800 MHz.
  • DDR4- a new, super modern type of RAM, ahead of its counterparts in terms of performance ( clock frequency) and voltage consumption (and therefore characterized by lower heat generation). Support for frequencies from 2133 to 4266 MHz is announced. On this moment These modules have not yet entered mass production (they promise to release them into mass production in mid-2012). Officially, fourth generation modules operating in DDR4-2133 at a voltage of 1.2 V were presented at CES, by Samsung January 04, 2011.

Amount of RAM.

I won’t write much about memory capacity. Let me just say that it is in this case that size matters :)
Just a few years ago, RAM of 256-512 MB satisfied all the needs of even cool gaming computers. Currently for normal functioning separately only operating system Windows 7 requires 1 GB of memory, not to mention applications and games. There will never be extra RAM, but I’ll tell you a secret that 32 bit windows Uses only 3.25 GB of RAM even if you install all 8 GB of RAM. You can read more about this.

Dimensions of the planks or the so-called Form factor.

Form - factor- This standard sizes RAM modules, type of design of the RAM strips themselves.
DIMM(Dual InLine Memory Module - a double-sided type of module with contacts on both sides) - mainly intended for desktop desktop computers, A SO-DIMM used in laptops.

Clock frequency.

This is pretty important technical parameter random access memory. But the motherboard also has a clock frequency, and it is important to know the operating bus frequency of this board, since if you bought, for example, a RAM module DDR3-1800, and the motherboard slot (connector) supports the maximum clock frequency DDR3-1600, then the RAM module as a result will operate at a clock frequency of 1600 MHz. In this case, all sorts of failures, errors in the operation of the system, etc. are possible.

Note: Memory bus frequency and processor frequency are completely different concepts.

From the tables above, you can understand that the bus frequency, multiplied by 2, gives the effective memory frequency (indicated in the “chip” column), i.e. gives us the data transfer speed. The name tells us the same thing. DDR(Double Data Rate) - which means double the data transfer rate.
For clarity, I will give an example of decoding in the name of the RAM module - Kingston/PC2-9600/DDR3(DIMM)/2Gb/1200MHz, Where:
—Kingston- manufacturer;
- PC2-9600— name of the module and its capacity;
- DDR3(DIMM)— memory type (form factor in which the module is made);
— 2Gb— module volume;
- 1200MHz— effective frequency, 1200 MHz.

Bandwidth.

Bandwidth- a memory characteristic on which system performance depends. It is expressed as the product of frequency system bus on the amount of data transmitted per clock cycle. Throughput (peak data rate) is a comprehensive measure of capability RAM, it takes into account transmission frequency, bus width and the number of memory channels. The frequency indicates the potential of the memory bus per clock cycle - at a higher frequency, more data can be transferred.
The peak indicator is calculated using the formula: B=f*c, Where:
B is the bandwidth, f is the transmission frequency, c is the bus width. If you use two channels to transmit data, we multiply everything received by 2. To get a figure in bytes/s, you need to divide the result by 8 (since there are 8 bits in 1 byte).
For better performance RAM bus bandwidth And processor bus bandwidth must match. For example, for Intel processor core 2 duo E6850 with a system bus of 1333 MHz and a bandwidth of 10600 Mb/s, you can install two modules with a bandwidth of 5300 Mb/s each (PC2-5300), in total they will have throughput system bus (FSB) equal to 10600 Mb/s.
Bus frequency and bandwidth are denoted as follows: “ DDR2-XXXX" And " PC2-YYYY". Here "XXXX" denotes the effective memory frequency, and "YYYY" the peak bandwidth.

Timings (latency).

Timings (or latency)- these are time delays of the signal, which, in the technical characteristics of the RAM, are written in the form “ 2-2-2 " or " 3-3-3 " etc. Each number here expresses a parameter. In order it is always " CAS Latency"(working cycle time), " RAS to CAS Delay" (time full access) And " RAS Precharge Time» (pre-charge time).

Note

So that you can better understand the concept of timings, imagine a book, it will be our RAM that we access. Information (data) in a book (RAM) is distributed among chapters, and chapters consist of pages, which in turn contain tables with cells (as in Excel tables). Each cell with data on the page has its own vertical (columns) and horizontal (rows) coordinates. To select a row, the RAS (Raw Address Strobe) signal is used, and to read a word (data) from the selected row (i.e., to select a column), the CAS (Column Address Strobe) signal is used. The full reading cycle begins with the opening of the “page” and ends with its closing and recharging, because otherwise the cells will be discharged and the data will be lost. This is what the algorithm for reading data from memory looks like:

  1. the selected "page" is activated by applying the RAS signal;
  2. data from the selected line on the page is transmitted to the amplifier, and a delay is required for data transmission (it is called RAS-to-CAS);
  3. a CAS signal is given to select a (column) word from that row;
  4. data is transferred to the bus (from where it goes to the memory controller), and a delay also occurs (CAS Latency);
  5. the next word comes without delay, since it is contained in the prepared line;
  6. after access to the row is completed, the page is closed, the data is returned to the cells and the page is recharged (the delay is called RAS Precharge).

Each number in the designation indicates how many bus cycles the signal will be delayed. Timings are measured in nanoseconds. The numbers can have values ​​from 2 to 9. But sometimes a fourth one is added to these three parameters (for example: 2-3-3-8), called “ DRAM Cycle Time Tras/Trc” (characterizes the performance of the entire memory chip as a whole).
It happens that sometimes a cunning manufacturer indicates only one value in the RAM characteristics, for example “ CL2"(CAS Latency), the first timing is equal to two clock cycles. But the first parameter does not have to be equal to all timings, and may be less than others, so keep this in mind and do not fall for the manufacturer’s marketing ploy.
An example to illustrate the impact of timings on performance: a system with memory at 100 MHz with 2-2-2 timings has approximately the same performance as the same system at 112 MHz, but with 3-3-3 timings. In other words, depending on latency, the performance difference can be as much as 10%.
So, when choosing, it is better to buy memory with the lowest timings, and if you want to add a module to an already installed one, then the timings of the purchased memory must match the timings of the installed memory.

Memory operating modes.

RAM can work in several modes, if of course such modes are supported by the motherboard. This single channel, two-channel, three-channel and even four-channel modes. Therefore, when choosing RAM, you should pay attention to this module parameter.
Theoretically, the speed of operation of the memory subsystem in dual-channel mode increases by 2 times, in three-channel mode - by 3 times, respectively, etc., but in practice, in dual-channel mode, the performance increase, unlike single-channel mode, is 10-70%.
Let's take a closer look at the types of modes:

  • Single channel mode(single-channel or asymmetric) – this mode is activated when only one memory module is installed in the system or all modules differ from each other in memory capacity, operating frequency or manufacturer. It doesn’t matter what slots or memory you install into. All memory will run at the speed of the slowest memory installed.
  • Dual Mode(dual-channel or symmetrical) – the same amount of RAM is installed in each channel (and theoretically doubles maximum speed data transmission). In dual-channel mode, memory modules work in pairs: 1st with 3rd and 2nd with 4th.
  • Triple Mode(three-channel) – the same amount of RAM is installed in each of the three channels. Modules are selected according to speed and volume. To enable this mode, modules must be installed in slots 1, 3 and 5/or 2, 4 and 6. In practice, by the way, this mode is not always more productive than the two-channel one, and sometimes even loses to it in data transfer speed.
  • Flex Mode(flexible) – allows you to increase the performance of RAM when installing two modules of different sizes, but the same operating frequency. As in dual-channel mode, memory cards are installed in the same connectors of different channels.

Generally, the most common option is dual-channel memory mode.
To operate in multi-channel modes, there are special sets of memory modules - the so-called Kit memory(Kit set) - this set includes two (three) modules, from the same manufacturer, with the same frequency, timings and memory type.
Appearance of KIT kits:
for dual channel mode

for three-channel mode

But the most important thing is that such modules are carefully selected and tested by the manufacturer itself to work in pairs (triples) in two- (three-) channel modes and do not imply any surprises in operation and configuration.

Manufacturer of modules.

Now on the market RAM Such manufacturers as have proven themselves well: Hynix, amsung, Corsair, Kingmax, Transcend, Kingston, OCZ…
Each company has its own for each product marking number, from which, if deciphered correctly, you can find out a lot of useful information about the product. Let's try to decipher the module marking as an example Kingston families ValueRAM(see image):

Explanation:

  • KVR– Kingston ValueRAM i.e. manufacturer
  • 1066/1333 – operating/effective frequency (Mhz)
  • D3- memory type (DDR3)
  • D (Dual) – rank/rank. A dual-rank module is two logical modules soldered onto one physical channel and alternately using the same physical channel (needed to achieve the maximum amount of RAM when limited quantities slots)
  • 4 – 4 DRAM memory chips
  • R – Registered, indicates stable operation without failures or errors for as long a continuous period of time as possible
  • 7 – signal delay (CAS=7)
  • S– temperature sensor on the module
  • K2– set (kit) of two modules
  • 4G– the total volume of the kit (both slats) is 4 GB.

Let me give you another example of marking CM2X1024-6400C5:
From the labeling it is clear that this is DDR2 module volume 1024 MB standard PC2-6400 and delays CL=5.
Stamps OCZ, Kingston And Corsair recommended for overclocking, i.e. have the potential for overclocking. They will have small timings and a clock frequency reserve, plus they are equipped with radiators, and some even coolers for heat removal, because When overclocking, the amount of heat increases significantly. The price for them will naturally be much higher.
I advise you not to forget about fakes (there are a lot of them on the shelves) and buy RAM modules only in serious stores that will give you a guarantee.

Finally:
That's all. With the help of this article, I think you will no longer be mistaken when choosing RAM for your computer. Now you can choose the right RAM for the system and increase its performance without any problems. Well, for those who will buy RAM (or have already bought it), I will dedicate the following article, in which I will describe in detail how to install RAM correctly into the system. Do not miss…

Modern market computer components It is developing so rapidly that even advanced users do not have time to understand the differences between one or another technology before a new one appears. The situation is exactly the same with RAM modules. Recently, everyone was discussing the advantages of the “troika” over the standard “two,” as both the “four” and the improved “troika” with the letter L have already appeared. Only a very knowledgeable person on this topic. But you need to figure out what the difference is between DDR3 and DDR3L. Let's start from the beginning.

The essence of the DDR3 standard

Unlike the outdated “two”, in the third version the capacity of the microcircuits has been increased. Now it is 8 bits. This could not but have a positive impact on productivity. The minimum volume of modules has also increased - now it is 1 gigabyte. Less is simply impossible. The difference between DDR3 and DDR3L, which we will look at below, is insignificant. There is more difference between a "two" and a "three". And it is visible to the naked eye. By the way, energy consumption has also decreased, which has made this type memory more suitable for mobile computers(laptops).

"Troika" is not a new standard. Therefore, there is nothing to be particularly happy about here. DDR4 is much more powerful. But, nevertheless, it is this type of memory that is most common in our time. DDR3 and DDR3L, the difference in which is not so significant, are the same type of modules. But it is worth understanding what distinguishes them, at least for self-education. Well, now let’s look at the characteristics of the “troika” with the letter L.

DDR3L. What's new?

Essentially, everything in this memory is standard. As in a regular "troika". But there is one significant difference - energy consumption. In 3L it is equal to 1.35 V. For comparison, a regular “three” consumes 1.50 V. This is quite significant when we talk about laptops, netbooks and ultrabooks, that is, mobile computers. In their case, power consumption plays a decisive role, since they need to operate on battery power for quite a long time. This is the difference between DDR3 and DDR3L. The difference is not that noticeable, but significant.

IN Lately Manufacturers of mobile computers use only energy-efficient "troika" modules. Therefore, it has become possible to make laptops last longer on battery power than was previously the case. Although the indicators are not very different. DDR3 and DDR3L, the difference in which is discussed here, are currently the most acceptable options for personal computers and laptops. Now let's look at the most popular models.

Kingston 4GB DDR3 PC3-10600

This module is perfect for medium-sized laptops price segment. It operates at a frequency of 1333 megahertz, the operating voltage is 1.35 V. This is both DDR3 and DDR3L, the difference between which is not particularly significant, in one bottle. The volume of this RAM is 4 gigabytes, which is quite enough for work and graphic applications. Multimedia will also work great. This module looks ideal in terms of price-quality ratio.

As usual, Kingston pleases users with fast and high-quality RAM. But don't forget about practicality. The fact is that this RAM costs quite a lot compared to its technical characteristics. Therefore, its purchase seems questionable from a practicality point of view. You need to think twice before buying this memory module. Otherwise, this is an excellent and durable RAM, of which there are few in the world. modern market.

Samsung 4GB DDR3 PC3-12800

Another module from the very middle price segment. This RAM already runs at 1600 megahertz and can even be used for gaming. A tandem of two such memory modules is especially productive. There are DDR3 and DDR3L "strips", but there is a difference between them. Like all equipment from this company, memory modules are of the highest quality and unsurpassed reliability. Currently, these are one of the best modules in the modern computer components market.

Samsung is well known quality smartphones and other devices. But its specialists could have made the RAM modules better. There is not even a shadow of the legendary Korean quality in them. But the memory works well. Although it doesn't look particularly strong or reliable. By the way, she takes acceleration very painfully. Right up to the saddest consequences. So there is no point in subjecting her to such a procedure. So let's continue. DDR3L and DDR3. What's the difference between them?

Crucial 4GB DDR3 PC3-12800

Another budget 3L standard RAM module. Its operating frequency is 1600 megahertz. The operating voltage is 1.35 V. This is standard for energy-efficient memory. This memory module is nothing more outstanding. It’s just that in dual-channel mode it works much better than its predecessors. Two such modules can significantly improve the performance of any laptop. And this is their main merit. This one is inexpensive. That's why it is the most common.

This is a legendary manufacturer of RAM modules. Everyone remembers its high-performance models for gaming computers. But even in the budget segment, Crucial did not lose face. The modules turned out to be productive, reliable and energy efficient, which is important for laptop owners. It's nice that the legendary manufacturer has finally turned to face laptop lovers.

Conclusion

So, we looked at DDR3 and DDR3L memory types. The difference in them, although insignificant, is there. And if you ever want to change the RAM in your laptop, be sure to purchase an energy-efficient type. Today, any computer component manufacturer produces such RAM. The most popular and reliable models are listed above. But that's not all.

Here once again I was asked how to appearance you can determine the type of RAM. Because This question comes up periodically, I decided that it was better to show it once than to explain it a hundred times, and write an illustrated mini-review of types of RAM for PCs.

Not everyone is interested in this, that’s why I’m hiding it under the cat. Read

The most common types of RAM that have been and are used in personal computers commonly called SIMM, DIMM, DDR, DDR2, DDR3. You are unlikely to see SIMMs and DIMMs anymore, but DDR, DDR2 or DDR3 are now installed in most personal computers. So, in order

SIMM

SIMM for 30 contacts. Used in personal computers with processors from 286 to 486. Now it is already a rarity. SIMM for 72 contacts. This type of memory was of two types: FPM (Fast Page Mode) and EDO (Extended Data Out).

The FPM type was used on computers with 486 processors and the first Pentiums until 1995. Then EDO appeared. Unlike its predecessors, EDO begins fetching the next block of memory at the same time it sends the previous block to the CPU.

Structurally they are identical, they can only be distinguished by markings. Personal computers that supported EDO could also work with FPM, but the opposite was not always the case.

DIMM

That's what they called the type SDRAM memory(Synchronous DRAM). Since 1996, the majority Intel chipsets began to support this type of memory module, making it very popular until 2001. Most computers with Pentium processors and Celeron used this type of memory.

DDR

DDR (Double Data Rate) was a development of SDRAM. This type of memory module first appeared on the market in 2001. The main difference between DDR and SDRAM is that instead of doubling the clock speed to speed things up, these modules transfer data twice per clock cycle.

DDR2

DDR2 (Double Data Rate 2) is a newer variant of DDR that should theoretically be twice as fast. DDR2 memory first appeared in 2003, and chipsets supporting it appeared in mid-2004. The main difference between DDR2 and DDR is the ability to operate at a significantly higher clock frequency, thanks to improvements in design. In appearance it differs from DDR in the number of contacts: it has increased from 184 (for DDR) to 240 (for DDR2).

DDR3

Like DDR2 memory modules, they are available in 240-pin printed circuit board(120 contacts on each side of the module), however, they are not electrically compatible with the latter, and for this reason they have a different “key” arrangement.

And finally, there is another type of RAM - RIMM (Rambus). Appeared on the market in 1999. It is based on traditional DRAM, but with a radically changed architecture. This type of RAM did not take root in personal computers and was used very rarely. Such modules were used back in game consoles Sony Playstation 2 and Nintendo 64.

SIMM for 30 contacts.


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