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A SIMM (single in-line memory module) is a module containing one or several random access memory ( RAM) chips on a small circuit board with pins that connect to the computer motherboard. Since the more RAM your computer has, the less frequently it will need to access your secondary storage (for example, hard disk or CD-ROM), PC owners sometimes expand RAM by installing additional SIMMs. SIMMs typically come with a 32 data bit (36 bits counting parity bits) path to the computer that requires a 72-pin connector. SIMMs usually come in memory chip multiples of four megabytes.

The memory chips on a SIMM are typically dynamic RAM (DRAM) chips. An improved form of RAM called Synchronous DRAM (SDRAM) can also be used. Since SDRAM provides a 64 data bit path, it requires at least two SIMMs or a dual in-line memory module ( DIMM).

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What is SIMM (single in-line memory module)? - Definition from WhatIs.com

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A SIMM (single in-line memory module) is a module containing one or several random access memory ( RAM) chips on a small circuit board with pins that connect to the computer motherboard.

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A DIMM (dual in-line memory module) is a double SIMM (single in-line memory module). Like a SIMM, a DIMM is a module that contains one or several random access memory ( RAM) chips on a small circuit board with pins that connect it to the computer motherboard.

A SIMM typically has a 32 data bit (36 bits counting parity bits) path to the computer that requires a 72-pin connector. For synchronous dynamic RAM ( SDRAM) chips, which have a 64 data bit connection to the computer, SIMMs must be installed in in-line pairs, since each one supports a 32-bit path. A single DIMM can be used instead. Originally, a DIMM had a 168-pin connector to support 64-bit data transfer.

As faster dynamic random access memory ( DRAM) was developed, DIMM circuit boards evolved. Modern DIMMs based on double data rate fourth generation (DDR4) SDRAM chips use 288-pin connectors to attach to the computer motherboard to enable the increase in data throughput. As clock speeds of the RAM chips increased, the 64-bit path handled increasing amounts of data.

Another evolution in DIMMs is the use of cooling fins or structures attached directly to the DIMM. The increase in chip density in typical 8 gigabyte (GB) or 16 GB DIMMS, and the increase in clock speed, led to an increase in heat production. This was made worse by the fact that DIMMs based on DDR4 RAM chips can be produced in capacities up to 64 GB.

Cooling structures on the DIMM help vent that heat into the computer enclosure and away from the motherboard and CPU.

SO-DIMM

While the standard DIMM is in the form of a rectangular stick approximately 5.5 inches in length, the small outline dual in-line memory module (SO-DIMM) is about half that size at 2.74 inches long. Both types of DIMMs are most commonly 1.2 inches tall, but both are made in a very low profile (VLP) format that is only 0.8 inches tall.

SO-DIMM form factor

SO-DIMM is mainly used for portable computing devices such as laptops and tablets. It differs from standard DIMM in that the DDR4 SO-DIMM has 260 pins versus 288 pins for the DRR4 DIMM.

Standard DIMMs are used in PCs and servers. The VLP DIMM was developed to meet the space requirements of blade servers.

DIMM trends and future outlook

The next type of memory that will be used in a DIMM is DDR5. In March 2017, the microelectronics standards organization, the JEDEC Solid State Technology Association, announced that it would publish the DDR5 specifications in 2018. Data transfer rates are expected to be double those of DDR4, which currently tops out at 25 gigabytes per second (GBps). JEDEC also stated that DDR5 will lower power consumption from DDR4 for an equivalent amount of RAM.

Other types of memory could make DDR5 obsolete shortly after it becomes generally available. At the same time it announced the timeframe for DDR5, JEDEC announced that it is continuing to work on the latest standards for nonvolatile DIMM ( NVDIMM), or nonvolatile memory used as system memory, like SDRAM.

DIMM form factor

Intel has released the first product in its Optane line, a nonvolatile memory system based on a technology known as phase-change memory. Intel's Optane may see enough adoption to possibly become the de facto technology before any NVDIMM based on the JEDEC standard hits the market.

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Margaret Rouse asks:

What do you think will happen to the in-line memory module in the near future?

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What is DIMM (dual in-line memory module)? - Definition from WhatIs.com

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A DIMM (dual in-line memory module) is a double SIMM (single in-line memory module). Like a SIMM, a DIMM is a module that contains one or several random access memory ( RAM) chips on a small circuit board with pins that connect it to the computer motherboard.

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RAM ( pronounced ramm) is an acronym for , a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is found in servers, PCs, tablets, smartphones and other devices, such as printers.

Main Types of RAM

There are two main types of RAM:

1. DRAM (Dynamic Random Access Memory)

2. SRAM (Static Random Access Memory)

DRAM (Dynamic Random Access Memory) - The term dynamic indicates that the memory must be constantly refreshed or it will lose its contents. DRAM is typically used for the main memory in computing devices. If a PC or smartphone is advertised as having 4-GB RAM or 16-GB RAM, those numbers refer to the DRAM, or main memory, in the device.

More specifically, most of the DRAM used in modern systems is synchronous DRAM, or SDRAM. Manufacturers also sometimes use the acronym DDR (or DDR2, DDR3, DDR4, etc.) to describe the type of SDRAM used by a PC or server. DDR stands for double data rate, and it refers to how much data the memory can transfer in one clock cycle.

In general, the more RAM a device has, the faster it will perform.

SRAM (Static Random Access Memory) - While DRAM is typically used for main memory, today SRAM is more often used for system cache. SRAM is said to be static because it doesn't need to be refreshed, unlike dynamic RAM, which needs to be refreshed thousands of times per second. As a result, SRAM is faster than DRAM. However, both types of RAM are volatile, meaning that they lose their contents when the power is turned off.

The Difference Between Memory, RAM and Storage

Sometimes, people get confused about the difference between memory and storage, in part because both can be measured in megabytes ( MB), gigabytes ( GB) and terabytes ( TB).

In common usage, the term RAM is synonymous with main memory. This is where a computing system stores data that it is actively using. Storage systems, such as hard drives, network storage devices or cloud storage, are where a system saves data that it will need to access later.

Computing systems can retrieve data from RAM very quickly, but when a device powers down, all the data that was in memory goes away. Many people have had the experience of losing a document they were working on after an unexpected power outage or system crash. In these cases, the data was lost because it was stored in system memory, which is volatile.

By contrast, storage is slower, but it can retain data when the device is powered down. So, for example, if a document has been saved to a hard drive prior to a power outage or system crash, the user will still be able to retrieve it when the system is back up and running.

Storage is usually less expensive than RAM on a per-gigabyte basis. As a result, most PCs and smartphones have many times more gigabytes of storage than gigabytes of RAM.

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What is RAM - Random Access Memory? Webopedia Definition

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RAM ( pronounced ramm) is an acronym for , a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is found in servers, PCs, tablets, smartphones and other devices, such as printers.

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CPU Basics: Multiple CPUs, Cores, and Hyper-Threading Explained

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CPU Basics: Multiple CPUs, Cores, and Hyper-Threading Explained

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The central processing unit (CPU) in your computer does the computational work-running programs, basically. But modern CPUs offer features like multiple cores and hyper-threading. Some PCs even use multiple CPUs. We're here to help sort it all out.

RELATED: Why You Can't Use CPU Clock Speed to Compare Computer Performance

The clock speed for a CPU used to be enough when comparing performance. Things aren't so simple anymore. A CPU that offers multiple cores or hyper-threading may perform significantly better than a single-core CPU of the same speed that doesn't feature hyper-threading. And PCs with multiple CPUs can have an even bigger advantage. All of these features are designed to allow PCs to more easily run multiple processes at the same time-increasing your performance when multitasking or under the demands of powerful apps like video encoders and modern games. So, let's take a look at each of these features and what they might mean to you.

Hyper-Threading

Hyper-threading was Intel's first attempt to bring parallel computation to consumer PCs. It debuted on desktop CPUs with the Pentium 4 HT back in 2002. The Pentium 4's of the day featured just a single CPU core, so it could really only perform one task at a time-even if it was able to switch between tasks quickly enough that it seemed like multitasking. Hyper-threading attempted to make up for that.

A single physical CPU core with hyper-threading appears as two logical CPUs to an operating system. The CPU is still a single CPU, so it's a little bit of a cheat. While the operating system sees two CPUs for each core, the actual CPU hardware only has a single set of execution resources for each core. The CPU pretends it has more cores than it does, and it uses its own logic to speed up program execution. In other words, the operating system is tricked into seeing two CPUs for each actual CPU core.

Hyper-threading allows the two logical CPU cores to share physical execution resources. This can speed things up somewhat-if one virtual CPU is stalled and waiting, the other virtual CPU can borrow its execution resources. Hyper-threading can help speed your system up, but it's nowhere near as good as having actual additional cores.

Thankfully, hyper-threading is now a "bonus." While the original consumer processors with hyper-threading only had a single core that masqueraded as multiple cores, modern Intel CPUs now have both multiple cores and hyper-threading technology. Your dual-core CPU with hyper-threading appears as four cores to your operating system, while your quad-core CPU with hyper-threading appears as eight cores. Hyper-threading is no substitute for additional cores, but a dual-core CPU with hyper-threading should perform better than a dual-core CPU without hyper-threading.

Multiple Cores

Originally, CPUs had a single core. That meant the physical CPU had a single central processing unit on it. To increase performance, manufacturers add additional "cores," or central processing units. A dual-core CPU has two central processing units, so it appears to the operating system as two CPUs. A CPU with two cores, for example, could run two different processes at the same time. This speeds up your system, because your computer can do multiple things at once.

Unlike hyper-threading, there are no tricks here - a dual-core CPU literally has two central processing units on the CPU chip. A quad-core CPU has four central processing units, an octa-core CPU has eight central processing units, and so on.

This helps dramatically improve performance while keeping the physical CPU unit small so it fits in a single socket. There only needs to be a single CPU socket with a single CPU unit inserted into it-not four different CPU sockets with four different CPUs, each needing their own power, cooling, and other hardware. There's less latency because the cores can communicate more quickly, as they're all on the same chip.

Windows' Task Manager shows this fairly well. Here, for example, you can see that this system has one actual CPU (socket) and four cores. Hyperthreading makes each core look like two CPUs to the operating system, so it shows 8 logical processors.

Multiple CPUs

RELATED: Why You Can't Use CPU Clock Speed to Compare Computer Performance

Most computers only have a single CPU. That single CPU may have multiple cores or hyper-threading technology-but it's still only one physical CPU unit inserted into a single CPU socket on the motherboard.

Before hyper-threading and multi-core CPUs came around, people attempted to add additional processing power to computers by adding additional CPUs. This requires a motherboard with multiple CPU sockets. The motherboard also needs additional hardware to connect those CPU sockets to the RAM and other resources. There's a lot of overhead in this kind of setup. There's additional latency if the CPUs need to communicate with each other, systems with multiple CPUs consume more power, and the motherboard needs more sockets and hardware.

Systems with multiple CPUs aren't very common among home-user PCs today. Even a high-powered gaming desktop with multiple graphics cards will generally only have a single CPU. You'll find multiple CPU systems among supercomputers, servers, and similar high-end systems that need as much number-crunching power as they can get.

The more CPUs or cores a computer has, the more things it can do at once, helping improve performance on most tasks.Most computers now have CPUs with multiple cores-the most efficient option we've discussed. You'll even find CPUs with multiple cores on modern smartphones and tablets. Intel CPUs also feature hyper-threading, which is kind of a bonus. Some computers that need a large amount of CPU power may have multiple CPUs, but it's much less efficient than it sounds.
Image Credit: lungstruck on Flickr, Mike Babcock on Flickr, DeclanTM on Flickr

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CPU Basics: Multiple CPUs, Cores, and Hyper-Threading Explained

# data[].attributes.attachment_link.description
The central processing unit (CPU) in your computer does the computational work-running programs, basically. But modern CPUs offer features like multiple cores and hyper-threading. Some PCs even use multiple CPUs. We're here to help sort it all out.