In this article, we discuss one of a computer's most significant parts, called RAM. We try to explain in detail about primary memory or temporary storage this is called RAM.
What is RAM (Random Access Memory)?
RAM stands for Random Access Memory. RAM is plugged into the motherboard in modules that are called DIMMs. DIMM stands for Dual Inline Memory Module. A DIMM is called a dual inline module because it has two independent rows of these pins, one on each side. A DIMM memory unit has 168, 184, 240, or 288 pins. And then the DIMM is installed on the motherboard in the memory slots.
A motherboard can have a several number of memory slots. The average motherboard will have between 2 and 4 number of slots. For data or programs to run on a computer, it first needs to be loaded into RAM. The data or program is first stored on the hard drive, then from the hard drive, it’s loaded into RAM. As soon data loaded into RAM, the CPU can now access the data or run the program accordingly.
Now most of the time if the RAM (memory) is too low it might not be able to hold all the data that the CPU needs. In this scenario then some data must be kept on the slower hard drive to compensate for the low memory.
In this case, instead of the data going from RAM to the CPU, it must do additional work by going back to the hard drive. And when this happens, it slows down the computer.
To resolve this issue all you need to do is increase the amount of RAM on a computer. Extending the memory, additional data can be loaded into the faster RAM without the need of repetitively accessing the slower hard drive.
The result is a faster performance of the computer. That’s why a computer with more RAM performs faster than a computer with less RAM. RAM requires continuous electrical power to store data. If the power is turned off, then the data is deleted from the memory.
Dynamic Random-Access Memory (DRAM)
There are different types of RAM, such as dynamic RAM or DRAM. DRAM is a memory that contains capacitors. A capacitor is like a small container that stores electricity and it’s in these capacitors that holds the bit of information such as a 1 or a 0.
Because computers understand the language and read data, which is 1s or 0s. And because DRAM has capacitors, they must be refreshed with electricity constantly because capacitors do not hold a charge for very long. This refreshing is where we get the name ‘dynamic’.
The capacitors must be dynamically refreshed frequently, otherwise they will overlook the information that they’re holding.
Synchronous Dynamic Random-Access Memory (SDRAM)
SDRAM which stands for synchronous DRAM. 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 essentially speed. The older DRAM technology operates Asynchronously with the system clock, which basically means that it runs slower than the system clock. Its signals are not matched with it but SDRAM runs in sync with the system clock. That’s why it is faster than DRAM because all the signals are tied to the system clock for better exact timing.
As we discussed before RAM is installed on the motherboard in modules that are called DIMMs. These DIMMs come in different memory sizes. They range 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.
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.
DIMMs have a 64-bit data path. Which means that they can transfer 64 bits of data at a time. Now before 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. DIMMs are faster than SIMMs because they can transfer double the amount of data per clock cycle because DIMMs transfer 64 bits of data at a time.
A memory DIMM is rated to have a 64-bit data path, then which means that it has an 8-byte wide data path or bus. Because 64 divided by 8 is equal to 8-byte.
Nowadays SDRAM is rated at different speeds. For example, a memory stick of old SDRAM in the late 1990s could be labelled 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 equals to 800 megabytes per second. The total Bandwidth of PC-100 equals 800 megabytes per second. So, PC-100 RAM can transfer data at a maximum rate of 800 megabytes per second.
SDRAM module labelled PC-133, you multiply 133 by 8 which is equal to 1066. So the total bandwidth for PC-133 equals 1066 megabytes per second.
Double Data Rate Random Access Memory (DDR RAM):
With the passage of time technology-enhanced, processor and bus speeds have changed to faster a new RAM technology was developed to keep up with the faster speeds of computers. This newer technology called DDR, stands for double data rate. 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.
DDR RAM is also labelled differently than non-DDR RAM. DDR RAM may include both the clock speed and the total bandwidth in its name. For example, a DDR DIMM labelled DDR-333 PC-2700 that’s means 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.
With the passage of time a new technology that has succeeded DDR is DDR2 which is faster than DDR. Because it allows for higher bus speeds and effectively sends double 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 labelled just like DDR. But with a small difference, DDR2 DIMM could be labelled DDR2-800 PC2-6400 and the difference is the ‘2’ right after the DDR and the ‘2’ right after the PC.
As the technology further develops a new RAM come after DDR2. DDR3 is twice as fast as DDR2 and it also uses less power than DDR2 just Like DDR2 DDR3 also has 240 pins, but the cuts in the DIMMs are in different places. 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.
The fourth generation of DDR SDRAM is DDR4, DDR4 DIMMs have 288 pins, and like its ancestors, 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 unbelievable maximum bandwidth of 34,100 megabytes per second.
