RAM Explained - Random Access Memory

Summary

This video delves into the intricacies of RAM, a critical component of computer systems. It explains that RAM, or Random Access Memory, is temporary storage found on motherboards in DIMMs. The video covers the evolution of RAM, from DRAM to SDRAM, and the advancements in DDR technology, which allows for faster data transfer rates. It also touches on the importance of RAM size for computer performance and the role of ECC memory in error correction, particularly for servers handling critical data.

Takeaways

• 💻 RAM (Random Access Memory) is a form of temporary storage located on the motherboard and is essential for running programs on a computer.
• 📏 DIMMs (Dual Inline Memory Modules) are the physical modules where RAM is stored, and they come in various pin configurations like 168, 184, 240, or 288 pins.
• 🚀 Increasing the amount of RAM in a computer can improve performance by allowing more data to be stored in the faster RAM, reducing reliance on slower hard drives.
• 🔋 RAM requires constant electrical power to store data, and when power is turned off, the data is erased.
• ⚡ DRAM (Dynamic RAM) contains capacitors that must be refreshed constantly to maintain the stored information, hence the term 'dynamic'.
• ⏱️ SDRAM (Synchronous DRAM) operates in sync with the system clock, making it faster than the older DRAM, which operates asynchronously.
• 📊 DDR (Double Data Rate) memory doubles the amount of data transferred per clock cycle compared to non-DDR RAM, improving data transfer speeds.
• 🔄 DDR2 and DDR3 are faster and more power-efficient than their predecessors, with each generation offering improvements in speed and pin configurations.
• 🔧 ECC (Error Correcting Code) RAM is used in servers to detect and correct data errors, ensuring higher reliability in critical systems.
• 🔍 RAM modules are labeled with their speed and bandwidth, such as DDR3-1600 PC3-12800, indicating their data transfer rate and maximum bandwidth.

Q & A

What is RAM and why is it important for a computer?

RAM stands for Random Access Memory and is the primary memory or temporary storage in a computer. It is important because data or programs need to be loaded into RAM before the CPU can access or run them, which is crucial for the computer's performance.

What does DIMM stand for and what is its role in a computer?

DIMM stands for Dual Inline Memory Module. It is the module on which RAM is stored on the motherboard, featuring two independent rows of pins on each side, and it plays a role in the installation and functioning of RAM in a computer.

How many pins does a DIMM memory module typically have?

A DIMM memory module typically has either 168, 184, 240, or 288 pins.

What happens when a computer's RAM is too low to hold all the data the CPU needs?

If the RAM is too low, some data has to be kept on the slower hard drive, causing the computer to perform extra work by accessing the hard drive instead of RAM, which slows down the computer.

How does increasing the amount of RAM in a computer affect its performance?

Increasing the amount of RAM allows more data to be loaded into the faster RAM, reducing the need to constantly access the slower hard drive, resulting in a faster performing computer.

What is the difference between DRAM and SDRAM?

DRAM, or Dynamic Random Access Memory, contains capacitors that need to be constantly refreshed with electricity as they leak charge. SDRAM, or Synchronous Dynamic Random Access Memory, operates in sync with the system clock and is faster than DRAM due to its coordinated signals with the system clock.

What is the significance of the data path in RAM modules?

The data path, such as 64-bit or 32-bit, refers to the number of bits of data transferred at a time or in one clock cycle. A wider data path allows for faster data transfer, improving the computer's performance.

How does the bandwidth of SDRAM modules like PC-100 and PC-133 compare?

The bandwidth of PC-100 is 800 megabytes per second (100 MHz x 8 bytes), while PC-133 has a bandwidth of 1066 megabytes per second (133.3333 MHz x 8 bytes, rounded off to 1066).

What is DDR RAM and how does it differ from non-DDR RAM?

DDR, or Double Data Rate RAM, sends double the amount of data in each clock cycle compared to non-DDR RAM by utilizing both the rising and falling edges of the clock signal, resulting in higher data transfer rates.

How does DDR2 RAM differ from DDR RAM?

DDR2 RAM allows for higher bus speeds and effectively sends twice the amount of data than DDR RAM. It also uses less power and has 240 pins compared to DDR's 184 pins.

What is the purpose of ECC in RAM modules and how can you identify it?

ECC, or Error-Correcting Code, detects and corrects data corruption in memory modules, which is crucial for applications that cannot tolerate data errors, such as servers. ECC modules can be identified by having nine memory chips instead of the standard eight on non-ECC DIMMs.

Outlines

00:00

🖥️ Understanding RAM and Its Functionality

This paragraph introduces Random Access Memory (RAM), explaining its role as primary memory or temporary storage in a computer. It describes how RAM is stored on the motherboard in modules called DIMMs (Dual Inline Memory Modules), and how data or programs must be loaded into RAM from the hard drive before the CPU can access or run them. The paragraph also discusses the importance of having enough RAM to prevent the computer from slowing down, as insufficient RAM forces the system to rely on the slower hard drive. The paragraph concludes with an explanation of how RAM stores data temporarily and the need for constant power to retain information.

05:04

💾 Differences Between DIMMs and SIMMs

This paragraph explains why DIMMs (Dual Inline Memory Modules) are faster than SIMMs (Single Inline Memory Modules). It emphasizes that DIMMs have a 64-bit data path, allowing them to transfer 64 bits of data at a time, compared to SIMMs which have a 32-bit data path. The paragraph also introduces the concept of bits and bytes, explaining that 8 bits equal 1 byte, and describes how SDRAM (Synchronous DRAM) is rated based on its speed, using examples like PC-100 and PC-133. It concludes by discussing how the total bandwidth of RAM is calculated by multiplying its speed by its bus width.

10:08

🚀 Evolution of RAM: DDR, DDR2, DDR3, and DDR4

This paragraph discusses the evolution of RAM technology, starting with DDR (Double Data Rate) memory, which doubles the amount of data transferred in each clock cycle by using both the rising and falling edges of the clock signal. It then introduces DDR2, which is faster and more power-efficient than DDR, followed by DDR3, which offers even greater speed and efficiency. The paragraph highlights the differences in pin configuration among these generations, preventing their use in the same motherboard slots. Finally, it describes DDR4, which offers the highest speed and lowest power consumption among these technologies, and introduces ECC (Error Correcting Code) memory used in servers to prevent data corruption.

Keywords

💡RAM

RAM stands for Random Access Memory and is the primary memory of a computer system. It is temporary storage that holds data and program instructions that the CPU needs to access quickly. The video emphasizes the importance of RAM for the computer's performance, explaining that more RAM allows more data to be loaded quickly, which can result in a faster computer. The script also clarifies that RAM requires constant electrical power to store data, which is why it is called 'volatile' memory.

💡DIMM

DIMM is an acronym for Dual Inline Memory Module, which is the physical module that houses the RAM. The script explains that these modules have a specific number of pins, such as 168, 184, 240, or 288, and are installed in memory slots on the motherboard. DIMMs are crucial for understanding how RAM is physically integrated into a computer system.

💡CPU

CPU, or Central Processing Unit, is the primary component of a computer that performs most of the processing. The video script mentions that the CPU accesses data or runs programs from the RAM. The relationship between RAM and CPU is fundamental to the computer's operation, as the speed and amount of RAM can affect the CPU's efficiency.

💡DRAM

DRAM, or Dynamic Random Access Memory, is a type of RAM that uses capacitors to store bits of data. The script explains that DRAM needs to be constantly refreshed with electricity because the capacitors leak charge over time. DRAM is a key concept in understanding how RAM stores data and why it requires continuous power.

💡SDRAM

SDRAM stands for Synchronous Dynamic Random Access Memory. It is an advancement over DRAM, operating in sync with the system clock, which makes it faster. The script uses SDRAM to illustrate the evolution of RAM technology and how it has improved the speed of data transfer within a computer.

💡Data Path

The term 'data path' refers to the width of the data bus, which is the number of bits of data that can be transferred in one clock cycle. The script explains that a 64-bit data path, as found in DIMMs, can transfer 64 bits of data at a time, which is twice the amount of a 32-bit data path found in older SIMMs, thus making DIMMs faster.

💡Bandwidth

Bandwidth in the context of RAM refers to the maximum rate at which data can be transferred. The script provides examples of how to calculate the bandwidth of different types of SDRAM, such as PC-100 and PC-133, by multiplying the clock speed by the data path width, illustrating the importance of bandwidth in determining the performance of RAM.

💡RDRAM

RDRAM, or Rambus Dynamic Random Access Memory, was a type of memory developed by Rambus Inc. The script mentions RDRAM as an example of a memory technology that was once a breakthrough in speed but eventually fell behind due to advancements in other technologies like DDR. RDRAM is an example of the evolution and competition in RAM technologies.

💡DDR

DDR stands for Double Data Rate, which is a type of SDRAM that can transfer data on both the rising and falling edges of the clock signal, effectively doubling the amount of data transferred compared to SDRAM. The script explains DDR as a significant advancement in RAM technology that improved data transfer rates and contributed to faster computer performance.

💡DDR2, DDR3, DDR4

DDR2, DDR3, and DDR4 are successive generations of DDR RAM, each offering higher speeds and improved power efficiency. The script outlines the progression of these technologies, with DDR4 being the fastest and most efficient, as an example of the continuous improvement in RAM capabilities.

💡ECC

ECC stands for Error-Correcting Code, a feature found in some RAM modules that can detect and correct data corruption. The script explains that ECC is crucial for applications where data integrity is critical, such as in servers handling financial or medical data, and that ECC modules have an additional memory chip to perform these functions.

Highlights

RAM, or Random Access Memory, is a crucial component of a computer that serves as primary memory or temporary storage.

RAM is stored on the motherboard in modules known as DIMMs, or Dual Inline Memory Modules.

DIMMs have two independent rows of pins and can have 168, 184, 240, or 288 pins.

A motherboard typically has 2 to 4 memory slots for DIMM installation.

Data or programs must be loaded into RAM from the hard drive to be processed by the CPU.

Low memory capacity can lead to slower performance as the CPU has to access the slower hard drive for additional data.

Increasing RAM capacity enhances computer performance by allowing more data to be stored in faster RAM.

RAM requires constant power to retain data, which is lost when power is turned off.

DRAM, or Dynamic Random Access Memory, is a type of RAM that uses capacitors to store bits of information.

SDRAM, or Synchronous Dynamic Random Access Memory, operates in sync with the system clock, making it faster than DRAM.

DIMMs come in various memory sizes, ranging from 128 MB to 32 GB per module.

The data path of a DIMM is 64 bits, allowing for the transfer of 8 bytes of data per clock cycle.

SIMMs, or Single Inline Memory Modules, have a 32-bit data path, making them slower than DIMMs.

SDRAM speed is indicated by labels like PC-100, with the number representing the maximum operating speed in MHz.

RDRAM, developed by Rambus, was initially faster than SDRAM but had a narrower data bus, limiting its bandwidth.

DDR, or Double Data Rate, RAM sends double the amount of data in each clock cycle compared to non-DDR RAM.

DDR RAM is labeled with both clock speed and total bandwidth, such as DDR-333 PC-2700.

DDR2, DDR3, and DDR4 are successive generations of DDR RAM, each offering higher speeds and lower power consumption.

ECC, or Error-Correcting Code, RAM is used in critical applications like servers to prevent data corruption.

ECC RAM modules have an additional memory chip compared to non-ECC DIMMs, totaling nine chips for error detection and correction.

Transcripts

Hello everyone, in this video

we're going to talk about one of the most important parts of a computer and we're going to be talking about primary memory or

temporary storage, and this is called RAM.

RAM stands for Random Access Memory.

RAM is stored on the motherboard in modules that are called DIMMs.

DIMM stands for Dual Inline Memory Module. A DIMM is a dual inline module because it has two

independent rows of these pins, one on each side.

A DIMM memory module has either

168, 184, 240, or 288 pins.

And then the DIMM is installed on the motherboard in the memory slots.

A motherboard can have a various number of memory slots. The average motherboard will have between 2 and 4 of them.

In order for data or program to run on a computer. It needs to be loaded into RAM first.

So the data or program is first stored on the hard drive, then from the hard drive, it's loaded into RAM

And once it's loaded into RAM, the CPU can now access the data or run the program.

Now a lot of times if the memory is too low it might not be able to hold all the data that the CPU needs.

And when this happens, then some other data has to be kept on the slower hard drive to compensate for the low memory.

So instead of the data going from RAM to the CPU, it has to do extra work by going back to the hard drive.

And when this happens, it slows down the computer.

So to solve this problem

all you need to do is increase the amount of RAM on a computer and

by increasing the memory, more data can be loaded into the faster RAM

without the need of constantly accessing the slower hard drive.

And the result is a faster performing computer.

So this is why a computer with more RAM performs faster than a computer with less RAM.

RAM requires constant electrical power to store data. And if the power is turned off, then the data is erased.

RAM also comes in different types such as dynamic RAM or DRAM.

DRAM is memory that contains capacitors.

A capacitor is like a small bucket that stores electricity, and it's in these capacitors that holds the bit of information

such as a 1 or a 0.

Because that's how computers read data, which is 1s or 0s

And because DRAM has capacitors, they have to be refreshed with electricity

constantly because capacitors do not hold a charge for very long,

they constantly leak. And this refreshing is where we get the name 'dynamic'.

The capacitors have to be dynamically refreshed often, otherwise they will forget the information that they're holding.

Another type of memory is called

SDRAM which stands for synchronous DRAM. And this type of memory is what is used today in RAM DIMMs.

SDRAM also has capacitors like DRAM, but the difference between

SDRAM and DRAM is basically speed. The older DRAM technology operates

Asynchronously with the system clock, which basically means that it runs slower than the system clock.

Because it's signals are not coordinated with it

but SDRAM runs in sync with the system clock.

Which is why it is faster than DRAM. All the signals are tied to the system clock

for a better controlled timing.

So as stated before RAM is stored on the motherboard in

modules that are called DIMMs and these DIMMs come in different memory sizes. Today they range anywhere from

128 megabytes to 32 gigabytes per DIMM.

SDRAM is also rated at different speeds. But before we talk about the speed of RAM, we need to define some things first.

Now the term 64 or 32 bit data path, refers to the number of bits of data that are

transferred at a time or in one clock cycle.

The more bits that are transferred in one clock cycle, then the faster the computer will be.

Now DIMMs have a 64 bit data path. Which means that they can transfer 64 bits of data at a time.

Now prior to DIMMs there was an older RAM module called a SIMM. And SIMMs had a

32 bit data path. Which means they can transfer data 32 bits at a time.

So that's why DIMMs are faster than SIMMs, because they can transfer twice the amount of data per clock cycle,

because DIMMs transfers 64 bits of data at a time.

compared to SIMMs which transfer 32 bits of data at a time.

Now a single bit, or one bit of data, is the smallest form of data that the computer reads.

Because in the computing world, a computer only

understands 1s and 0s, which is represented by a single bit of data.

Now there is also the term byte. And 8 bits is equal to 1 byte.

So if a memory DIMM is rated to have a

64-bit data path, then that means that it has an 8 byte wide data path or bus.

Because 64 divided by 8 = 8

SDRAM is rated at different speeds. For example a stick of old SDRAM way back in the late 1990s

could be labeled PC-100.

The 100 equals a maximum speed at which it operates, which is 100 MHz and

Since SDRAM only comes in 64-bit modules, as we discussed earlier,

it has an 8 byte wide bus, because 64 divided by 8 = 8

So to figure out the total bandwidth of PC-100, you multiply 100 MHz x 8 bytes

which equals 800 megabytes per second.

So the total Bandwidth of PC-100 equals 800 megabytes per second.

So in other words PC-100 RAM can transfer data at a maximum rate of 800 megabytes per second.

So an SDRAM module labeled PC-133, you multiply 133 by 8 which = 1066.

So the total bandwidth for PC-133 equals

1066 megabytes per second. Now technically 133 x 8 actually equals 1064

But 1066 is accurate because the actual clock speed is

133.3333 x 8, which is rounded off to 1066

Another type of memory was called RDRAM, which was developed by Rambus inc.

And they developed the RIMM which stands for Rambus inline memory module.

RIMMs have 184 pins and looks similar to DIMMs.

With the exception that the bottom notches are located in the center of the module.

In 1999 RIMMs were breakthrough in the speed of memory,

But has quickly fallen behind due to the advancement of technology in DIMMs.

When RDRAM debuted in 1999 it ran at 800 MHz which was considerably faster than

SDRAM which ran at 133 MHz at that time

But even though it was a lot faster than SDRAM, RDRAM only had a 2 byte wide bus,

compared to SDRAM, which had an 8 byte wide bus

So if you multiply the speed of RDRAM, which was 800 MHz x the bus width, which was 2 bytes,

you would get a total bandwidth of 1600 megabytes per second

As technology increased and processor and bus speeds have gotten faster a new RAM

technology was developed to keep up with the faster speeds of computers. This newer technology was called DDR,

which stands for double data rate, and that's basically what DDR does,

it sends double the amount of data in each clock cycle

Compared to non DDR. Non DDR, or single data rate RAM.

Uses only the rising edge of the clock signal to transfer data

But DDR uses both the rising and falling edges of the clock signal to send data. Which gives DDR

the ability to send twice the amount of data

So here is another illustration

comparing the difference between DDR and non DDR

So even though the system clock is pulsating at the same speed for both RAM modules,

the DDR RAM module can send twice the amount of data, since it takes advantage of both the rising and falling

edges of the clock signal.

So even if we speed the clock up and make it go faster, the DDR RAM will still send twice the amount of data

compared to the non DDR RAM.

DDR ss also labeled differently than non DDR RAM.

DDR RAM may include both the clock speed and the total bandwidth in its name.

So instead of just including the clock speed in its name, like PC-133, where 133 equals the clock speed.

DDR includes the total bandwidth also.

So for example a DDR DIMM labeled DDR-333 PC-2700

The 333 is the clock speed, and the 2700 is the actual total bandwidth.

so 333 MHz x 8 bytes = 2700 megabytes per second, which is where we get the name PC-2700

A new technology that has succeeded DDR is DDR2

DDR2 is faster than DDR

because it allows for higher bus speeds and effectively send twice the amount of data than DDR

and it also uses less power than DDR

A DDR2 DIMM has 240 pins compared to DDR, which has 184 pins.

DDR2 is labeled just like DDR. But with a small difference

for example a DDR2 DIMM could be labeled DDR2-800 PC2-6400

and the difference is the '2' right after the DDR and the '2' right after the PC.

So this is how you can identify DDR2 memory

By using its label

and right after DDR2 is DDR3

DDR3 is twice as fast as DDR2 and it also uses less power than DDR2

and just Like DDR2

DDR3 also has

240 pins, but the notches in the DIMMs are in different places.

So you can't put a DDR3 DIMM in a RAM slot made for a DDR2

in fact motherboards are made to support a certain type of memory

so you can't mix DDR 1, 2, 3, or 4 on the same motherboard

An example of DDR3 would be DDR3-1600 PC3-12800

And the fourth generation of DDR SDRAM is DDR4

DDR4 DIMMs have

288 pins, and like its predecessors, it also uses less power than the previous generation of DDR

DDR4 also offers a higher range of speed than DDR3 such as DDR4-4266 PC4-34100

which has an incredible maximum bandwidth of

34,100 megabytes per second

Now sometimes there are circumstances where memory data corruption cannot be tolerated

for example in servers

servers are meant to be up and running at all times and

some servers cannot afford being offline for any reason. Such as servers that control financial data,

emergency medical data, or government data.

These servers cannot go down for any reason and that's why some RAM modules have

ECC which stands for error correcting code and

what ECC does is that it detects if the data was correctly processed by the memory module and

makes a correction if it needs to

You can tell if a RAM module has

ECC by counting the number of memory chips on the module. In a standard

Non-ECC DIMM, it will have eight memory chips

But in an ECC memory module it will have nine memory chips

Now most RAM modules today are non ECC

and this is because of the advance in technology that has minimized memory errors and

Has made non ECC RAM more stable. But as stated before

ECC memory is mostly used in servers because servers need to be up and running at all times and

using ECC memory is just an extra precaution to guard against any memory errors