RAM modules can be of various types. RAM

There are several common types of memory modules used in modern computers and computers that were released a few years ago but still work in homes and offices.
For many users, distinguishing them both in appearance and performance is a big problem.
In this article we will look at the main features of different memory modules.

FPM

FPM (Fast Page Mode) is a type of dynamic memory.
Its name corresponds to the principle of operation, since the module allows faster access to data that is on the same page as the data transferred during the previous cycle.
These modules were used on most 486-based computers and early Pentium-based systems around 1995.

EDO

EDO (Extended Data Out) modules appeared in 1995 as a new type of memory for computers with Pentium processors.
This is a modified version of FPM.
Unlike its predecessors, EDO begins fetching the next block of memory at the same time it sends the previous block to the CPU.

SDRAM

SDRAM (Synchronous DRAM) is a type of random access memory that works so fast that it can be synchronized with the processor frequency, excluding standby modes.
The microcircuits are divided into two blocks of cells so that while accessing a bit in one block, preparations are in progress for accessing a bit in another block.

If the time to access the first piece of information was 60 ns, all subsequent intervals were reduced to 10 ns.
Starting in 1996, most Intel chipsets began to support this type of memory module, making it very popular until 2001.

SDRAM can operate at 133 MHz, which is almost three times faster than FPM and twice as fast as EDO.
Most computers with Pentium and Celeron processors released in 1999 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.
Now this is the main memory standard, but it is already beginning to give way to DDR2.

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.

This memory, like DDR, transfers two sets of data per clock cycle.
The main difference between DDR2 and DDR is the ability to operate at significantly higher clock speeds, thanks to improvements in design.
But the modified operating scheme, which makes it possible to achieve high clock frequencies, at the same time increases delays when working with memory.

DDR3

DDR3 SDRAM (double data rate synchronous dynamic random access memory, third generation) is a type of random access memory used in computing as RAM and video memory.
It replaced DDR2 SDRAM memory.

DDR3 has a 40% reduction in energy consumption compared to DDR2 modules, which is due to the lower (1.5 V, compared to 1.8 V for DDR2 and 2.5 V for DDR) power supply voltage of the memory cells.
Reducing the supply voltage is achieved through the use of a 90-nm (initially, later 65-, 50-, 40-nm) process technology in the production of microcircuits and the use of Dual-gate transistors (which helps reduce leakage currents).

DIMMs with DDR3 memory are not mechanically compatible with the same DDR2 memory modules (the key is located in a different location), so DDR2 cannot be installed in DDR3 slots (this is done to prevent the mistaken installation of some modules instead of others - these types of memory are not the same according to electrical parameters).

RAMBUS (RIMM)

RAMBUS (RIMM) is a type of memory that appeared on the market in 1999.
It is based on traditional DRAM, but with a radically changed architecture.
The RAMBUS design makes memory access more intelligent, allowing pre-access to data while slightly offloading the CPU.

The basic idea used in these memory modules is to receive data in small bursts but at a very high clock speed.
For example, SDRAM can transfer 64 bits of information at 100 MHz, and RAMBUS can transfer 16 bits at 800 MHz.
These modules did not become successful as Intel had many problems with their implementation.
RDRAM modules appeared in the Sony Playstation 2 and Nintendo 64 game consoles.

Translation: Vladimir Volodin

More and more details are appearing on the Internet about Intel's Comet Lake-S processors.

Intel LGA1200 socket for PC processors

The release of 10th generation Intel Core Comet Lake processors for desktop PCs and motherboards based on 400 series chipsets (Z490, W480, Q470 and H410) is expected in the second half of 2020.

Greetings, dear readers! Today I will talk about the types of computer RAM. There are many varieties of it - enough to get confused in the parameters.

From this article you will learn:

A brief excursion into history

A long time ago, when computers were large, programs were small, and viruses did not exist at all, SIMM modules of several modifications were used: 30, 68 and 72 pins. They worked in conjunction with processors from 286 to 486 inclusive.

Now it is extremely difficult to find such a computer in working condition: there is no modern software for it. Programs that could theoretically be launched turn out to be too cumbersome in practice.

DIMM

The main difference from its predecessor is that the contacts located on both sides of the strip are independent, unlike the paired contacts on SIMM. SDRAM technology is already involved here - synchronous dynamic random access memory.
Mass production of this type of memory began in 1993. Such modules were intended primarily for the Intel Pentium or Celeron processor on a 64-bit data bus.

SO-DIMM memory modules are more compact as they are used in laptops.

DDR

More precisely, this type of memory is correctly called DDR SDRAM. It appeared on the market in 2001 and was used as RAM and video memory. The difference from its predecessor is the double frequency, since the bar is capable of transmitting data twice in one clock cycle.

This is the first type of memory module that can operate in dual-channel mode.

You can find out more about what dual-channel mode is.

And so yes, DDR SDRAM and its descendants are produced in the DIMM form factor, that is, they have independent contacts on both sides.

DDR2

This type of memory was able to compete with its predecessor already in 2004 and occupied a leading position until 2010. The sticks were produced in DIMM form factors for desktop computers and SO-DIMM for portable ones.

Compared to its predecessor, this type of memory has:

• Greater throughput;
• Less energy consumption;
• Improved cooling thanks to design.

The disadvantages include higher RAM timings. What it is .

DDR3

Like its predecessor, they are produced in the form of a 240-pin strip, but are incompatible due to different connectors (I’ll talk about this in more detail later).

The memory type is characterized by an even higher frequency and lower power consumption, as well as an increase in pre-swapping from 4 to 8 bits. There is a DDR3L modification with an operating voltage reduced to 1.35 V. By the way, about frequency. There are several modifications: 1066, 1333, 1600, 1866, 2133 or 2400 with the corresponding data transfer speed.
Produced since 2012. Computers using this type of memory are still in use today. The volume of installed modules is from 1 to 16 GB. In the SO-DIMM form factor, the “ceiling” is 8 GB.

DDR4

The fourth generation doubled the number of internal banks, thereby increasing the transfer speed of the external bus. Mass production began in 2014. The top models have a throughput of up to 3,200 million transmissions per second, and are available in modules ranging from 4 to 128 GB.

They already have 288 contacts. The physical dimensions of the part are the same, so the connectors are packed more tightly. Compared to DDR3, the height has been slightly increased.
SO-DIMMs have 260 pins located closer together.

What's next?

An interesting trend: with each next generation of memory, the timings increase, which engineers try to compensate for by increasing the operating frequency and data transfer speed. So effective that the next generation turns out to be faster than its predecessors.

That is why I once again draw your attention to the fact that when choosing components, try to “dance” from the DDR4 standard as the newest and most progressive.

Memory type compatibility

There is a misconception that, due to the interface features, it is impossible to insert a memory stick into unsuitable slots. I will say this: a strong enough guy (and even some girls) will insert anything anywhere - not only RAM, but also an Intel processor into an AMD slot. True, there is one BUT: such an assembly, alas, will not work.

Other users who carefully assemble computers usually cannot insert the RAM into the wrong slot. Even if the planks have the same dimensions, this will not allow making a so-called key. There is a small protrusion inside the slot that prevents mounting the wrong type of RAM. The appropriate strip has a small cutout in this place, so you can insert it without any problems.

How to determine the model

The utilities built into Windows allow you to find out only minimal information - the amount of installed memory. It is impossible to find out what type it is this way. Third-party software will come to the rescue, providing complete information about the system - for example, Everest or AIDA64.

The memory type is also specified in the BIOS. Where exactly this information is indicated and how to call the BIOS depends on its modification. In most cases, it is enough to hold down the Del button when starting the computer, but exceptions are possible.

Naturally, the marking is indicated on the RAM itself, or rather on the glued nameplate. To get to the bar, you will have to disassemble the case and dismantle it. In the case of a laptop, this simple task turns into a fascinating quest with detailed disassembly instructions.

Here, in fact, is all about the types of RAM, which is enough to know to independently select components. And if you are building a gaming computer, I recommend that you read the information.

Thank you for your attention and see you next time! Don't forget this blog and share posts on social networks.

RAM modules are made on the basis of rectangular printed circuit boards with single-sided or double-sided arrangement of chips. They differ in form factor and have different designs: SIMM (Single In-line Memory Module - memory module with single-row contacts); DIMM (Dual In-line Memory Module - memory module with double-row contacts); SO DIMM (Small Outline DIMM - small DIMM size). The contacts of the memory module connectors are coated with gold or an alloy of nickel and palladium.

ModulesSIMM is a board with flat contacts along one side; They are installed into the motherboard connector at an angle and then rotated to the working (vertical) position using latches. There are two types of SIMMs: 30-pin, 9-bit (8 data bits and 1 parity bit); 72-pin, 32-bit (no parity) or 36-bit (parity). Therefore, the 32-bit bus required the use of four banks of 30-pin SIMMs or one 72-pin module; for a 64-bit bus - two banks of 72-pin modules.

ModulesDIMM There are two types: 168-pin (for installing SDRAM chips) and 184-pin DIMMs (for DDR SDRAM chips). They are identical in installation dimensions, inserted vertically into the motherboard connector and secured with latches. During the transition period, motherboards were equipped with connectors for both types of DIMM modules, but currently SIMM and 168-pin DIMM modules are outdated and not used in PCs.

ModulesSO DIMM with 72- and 144-pin connectors are used in portable PCs. They are installed into the motherboard in the same way as SIMM modules.

Currently, the most popular DIMM modules are DDR SDRAM, DDR2 SDRAM and DDR3 SDRAM chips.

DIMMs based on DDR SDRAM chips are available with 184 pins (Fig. 1).

Rice. 1. 184-pin DIMM board:

1 - DDR SDRAM chips; 2 - buffer memory and error control chip; 3 - cutouts for mounting the board; 4 - key; 5 - connector

The key on the memory module is a cutout in the board, which, in combination with a corresponding protrusion in the motherboard connector, prevents the module from being installed the wrong way around. In addition, the key for incompatible RAM modules may have different placement (move between contacts in one direction or the other), indicating the supply voltage rating (2.5 or 1.8 V) and protecting against electrical damage.

Memory chips such as DDR2, DDR3, which replace DDR, are produced in the form of 240-pin DIMM modules.

Modern memory modules for PCs are supplied in 512 MB, 1.2 and 4 GB versions.

At the time of this writing, the market is dominated by third-generation DDR memory modules, or DDR3. DDR3 memory has higher clock speeds (up to 2400 megahertz), lower power consumption by approximately 30-40% (compared to DDR2) and correspondingly lower heat dissipation.

However, you can still find DDR2 memory and outdated (and therefore terribly expensive in places) DDR1 memory. All these three types are completely incompatible with each other, both electrically (DDR3 has lower voltage) and physical (see image).

The necessary and sufficient amount of RAM depends on the operating system and application programs that determine the intended use of the PC. If you plan to use the computer for office or “multimedia” purposes (Internet, working with office applications, listening to music, etc.), 1024 MB of memory (1 GB) will be enough for you. For demanding computer games, video processing, sound recording and mixing of musical compositions at home - at least 2 GB (2048 MB) of RAM. Preferably 3 gigabytes. It should also be noted that 32-bit versions (x86) of Windows do not support more than 3 gigabytes of RAM. We also note that the Windows Vista and Windows 7 operating systems require at least 1 GB of RAM to work comfortably with them, and up to 1.5 gigabytes when all graphic effects are enabled.

Characteristics and markings of RAM

Consider the markings

4096Mb (2x2048Mb) DIMM DDR2 PC2-8500 Corsair XMS2 C5 BOX

1024Mb SO-DIMM DDR2 PC6400 OCZ OCZ2M8001G (5-5-5-15) Retail

Volume

The first designation in the line is the size of the memory modules. In particular, in the first case it is 4 GB, and in the second case it is 1 GB. True, 4 GB in this case is implemented not by one memory stick, but by two. This is the so-called Kit of 2 - a set of two planks. Typically, such kits are purchased to install strips in dual-channel mode in parallel slots. The fact that they have the same parameters will improve their compatibility, which has a beneficial effect on stability.

Type of shell

DIMM/SO-DIMM is a type of memory stick housing. All modern memory modules are available in one of the two specified designs.

Memory type

Memory type is the architecture by which the memory chips themselves are organized. It affects all technical characteristics of memory - performance, frequency, supply voltage, etc.

Data transfer frequencies for memory types:

DDR: 200-400 MHz

DDR2: 533-1200 MHz

DDR3: 800-2400 MHz

The number indicated after the memory type is the frequency: DDR400, DDR2-800.

Memory modules of all types differ in supply voltage and connectors and cannot be inserted into each other.

The data transfer frequency characterizes the potential of the memory bus to transfer data per unit time: the higher the frequency, the more data can be transferred.

However, there are other factors, such as the number of memory channels and memory bus width. They also affect the performance of memory subsystems.

New generations of processors stimulated the development of faster SDRAM (Synchronous Dynamic Random Access Memory) with a clock frequency of 66 MHz, and memory modules with such chips were called DIMM (Dual In-line Memory Module).
For use with Athlon processors, and then with Pentium 4, the second generation of SDRAM chips was developed - DDR SDRAM (Double Data Rate SDRAM). DDR SDRAM technology allows data to be transferred on both edges of each clock pulse, which provides the ability to double memory bandwidth. With the further development of this technology in DDR2 SDRAM chips, it was possible to transmit 4 pieces of data in one clock pulse. Moreover, it should be noted that the increase in performance occurs due to optimization of the process of addressing and reading/writing memory cells, but the clock frequency of the memory matrix does not change. Therefore, the overall performance of the computer does not increase by two or four times, but only by tens of percent. In Fig. The frequency principles of operation of SDRAM microcircuits of various generations are shown.

The following types of DIMMs exist:

• 72-pin SO-DIMM (Small Outline Dual In-line Memory Module) - used for FPM DRAM (Fast Page Mode Dynamic Random Access Memory) and EDO DRAM (Extended Data Out Dynamic Random Access Memory)

• 100-pin DIMM - used for SDRAM (Synchronous Dynamic Random Access Memory) printers

• 144-pin SO-DIMM - used for SDR SDRAM (Single Data Rate...) in laptop computers

• 168-pin DIMM - used for SDR SDRAM (less commonly for FPM/EDO DRAM in workstations/servers

• 172-pin MicroDIMM - used for DDR SDRAM (Double date rate)

• 184-pin DIMM - used for DDR SDRAM

• 200-pin SO-DIMM - used for DDR SDRAM and DDR2 SDRAM

• 214-pin MicroDIMM - used for DDR2 SDRAM

• 204-pin SO-DIMM - used for DDR3 SDRAM

• 240-pin DIMM - used for DDR2 SDRAM, DDR3 SDRAM and FB-DIMM (Fully Buffered) DRAM

• 244-pin Mini-DIMM – for Mini Registered DIMM

• 256-pin SO-DIMM - used for DDR4 SDRAM

• 284-pin DIMM - used for DDR4 SDRAM

To prevent installation of the wrong type of DIMM module, several slots (keys) are made in the module’s textolite board among the contact pads, as well as on the right and left in the area of ​​the module fixation elements on the system board. To mechanically identify different DIMM modules, a shift in the position of two keys in the module’s textolite board, located among the contact pads, is used. The main purpose of these keys is to prevent the installation of a DIMM module with an inappropriate supply voltage for memory chips into the socket. Additionally, the location of the key or keys determines the presence or absence of a data buffer, etc.

DDR modules are marked PC. But unlike SDRAM, where PC indicated the operating frequency (for example, PC133 - the memory is designed to operate at a frequency of 133 MHz), the PC indicator in DDR modules indicates the maximum achievable bandwidth, measured in megabytes per second.

DDR2 SDRAM

Standard name	Memory type	Memory frequency	Bus frequency	Data transfer per second (MT/s)
PC2-3200	DDR2-400	100 MHz	200 MHz	400	3200 MB/s
PC2-4200	DDR2-533	133 MHz	266 MHz	533	4200 MB/s
PC2-5300	DDR2-667	166 MHz	333 MHz	667	5300 MB/s
PC2-5400	DDR2-675	168 MHz	337 MHz	675	5400 MB/s
PC2-5600	DDR2-700	175 MHz	350 MHz	700	5600 MB/s
PC2-5700	DDR2-711	177 MHz	355 MHz	711	5700 MB/s
PC2-6000	DDR2-750	187 MHz	375 MHz	750	6000 MB/s
PC2-6400	DDR2-800	200 MHz	400 MHz	800	6400 MB/s
PC2-7100	DDR2-888	222 MHz	444 MHz	888	7100 MB/s
PC2-7200	DDR2-900	225 MHz	450 MHz	900	7200 MB/s
PC2-8000	DDR2-1000	250 MHz	500 MHz	1000	8000 MB/s
PC2-8500	DDR2-1066	266 MHz	533 MHz	1066	8500 MB/s
PC2-9200	DDR2-1150	287 MHz	575 MHz	1150	9200 MB/s
PC2-9600	DDR2-1200	300 MHz	600 MHz	1200	9600 MB/s

DDR3 SDRAM

Standard name	Memory type	Memory frequency	Bus frequency	Data transfer per second(MT/s)	Peak Data Rate
PC3-6400	DDR3-800	100 MHz	400 MHz	800	6400 MB/s
PC3-8500	DDR3-1066	133 MHz	533 MHz	1066	8533 MB/s
PC3-10600	DDR3-1333	166 MHz	667 MHz	1333	10667 MB/s
PC3-12800	DDR3-1600	200 MHz	800 MHz	1600	12800 MB/s
PC3-14400	DDR3-1800	225 MHz	900 MHz	1800	14400 MB/s
PC3-16000	DDR3-2000	250 MHz	1000 MHz	2000	16000 MB/s
PC3-17000	DDR3-2133	266 MHz	1066 MHz	2133	17066 MB/s
PC3-19200	DDR3-2400	300 MHz	1200 MHz	2400	19200 MB/s

The tables indicate exactly the peak values; in practice they may be unattainable.
To comprehensively evaluate the capabilities of RAM, the term memory bandwidth is used. It takes into account the frequency at which data is transmitted, the bus width and the number of memory channels.

Bandwidth = Bus frequency x channel width x number of channels

For all DDR, the number of channels = 2 and the width is 64 bits.
For example, using DDR2-800 memory with a bus speed of 400 MHz, the bandwidth will be:

(400 MHz x 64 bit x 2)/ 8 bit = 6400 MB/s

Each manufacturer gives each of its products or parts its internal production marking, called P/N (part number).
For memory modules from different manufacturers it looks something like this:

• Kingston KVR800D2N6/1G
• OCZ OCZ2M8001G
• Corsair XMS2 CM2X1024-6400C5

On the website of many memory manufacturers you can study how their Part Number is read.

Kingston Part Number	Description
KVR1333D3D4R9SK2/16G	16GB 1333MHz DDR3 ECC Reg CL9 DIMM (Kit of 2) DR x4 w/TS