What Is Computer [RAM] ?

 RAM stands for Random Access Memory.

DIMM stands for Dual Inline Memory Module.

DDR, it stands for double data rate

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

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.

 The DIMM is installed on the motherboard in the memory slots. A motherboard can have a various number of memory slots.

 The average the motherboard will have is between 2 and 4 of them. For data or programs to run on a computer. It needs to be loaded into RAM.

 The data or program is first stored on the hard drive, then from the hard drive, loaded into RAM And once it's loaded into RAM, the CPU can access the data or run the program.

The slower hard drive compensates 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.

 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. The result is a faster-performing computer.

A computer with more RAM performs faster than a computer with less RAM. RAM requires constant electrical power to store data.

Power is turned off, then the data is erased. RAM also comes in different types as dynamic RAM or DRAM. DRAM is a memory that contains capacitors. 

A capacitor is a small bucket that stores electricity, and capacitors that hold a bit of information such as a 1 or a 0. Computers read data, it 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.

 The capacitors have to be dynamically refreshed often, they will forget the information that they're holding. Another type of memory is called SDRAM its stands for synchronous DRAM.

Type of memory is in RAM DIMMs SDRAM also has capacitors like DRAM,

The older DRAM technology operates Asynchronously with the system clock, its basically means that it runs slower than the system clock.

SDRAM runs in sync with the system clock. It's faster than DRAM. All the signals are tied to the system clock for better-controlled timing.

RAM is stored on the motherboard in modules that are called DIMMs and these DIMMs came in different memory sizes. SDRAM is also rated at different speeds.  

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

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

 RAM module called a SIMM. And Simms had a 32-bit data path. they can transfer data 32 bits at a time.

DIMMs are faster than SIMMs because they can transfer twice the amount of data per clock cycle because DIMMs transfer 64 bits of data at a time. compared to SIMMs its transfers 32 bits of data at a time.

The smallest form of data that the computer reads.

Computing world, a computer only understands 1s and 0s, it is represented by a single bit of data. 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. 64 divided by 8 = 8 SDRAM is rated at different speeds.

 

SDRAM way back in the late 1990s could be labeled PC-100.

The 100 equals a maximum speed at it's it operates, its  100 MHz and Since SDRAM only comes in 64-bit modules, it has an 8-byte wide bus, because 64 divided by 8 = 8 to figure out the total bandwidth of PC-100, multiply 100 MHz x 8 bytes its equals 800 megabytes per second. Total Bandwidth of PC-100 equals 800 megabytes per second.

Important part ;

PC-100 RAM can transfer data at a maximum rate of 800 megabytes per second. SDRAM module labeled PC-133, you multiply 133 by 8 its = 1066.  The total bandwidth for PC-133 equals 1066 megabytes per second. Now technically 133 x 8 actually equals 1064  1066 is accurate because the actual clock speed is 133.3333 x 8, it is rounded off to 1066. Another type of memory was called RDRAM, which was by Rambus inc developed the RIMM stands for Rambus inline memory module. RIMMs have 184 pins and look similar to DIMMs the exception that the bottom notches are located in the center of the module.

 

In 1999 RIMMs were breakthrough in the speed of memory .   RDRAM debuted in 1999 it ran at 800 MHz its was considerably faster than SDRAM it can run at 133 MHz at that time   though it was a lot faster than SDRAM, RDRAM only had a 2-byte wide bus, compared to SDRAM, it has an 8-byte wide bus you  can multiply the speed of RDRAM, it was 800 MHz x the bus width, it  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 technology was called DDR, which stands for double the data rate and that's basically  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  DDR uses both the rising and falling edges of the clock signal to send data.  

 DDR the ability to send twice the amount of data  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. 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 is also labeled differently than non-DDR RAM. DDR RAM may include both the clock speed and the total bandwidth in its name. The clock speed in its name,   PC-133, where 133 equals the clock speed. DDR includes the total bandwidth. Example ; DDR DIMM labeled DDR-333 PC-2700 The 333 is the clock speed, and 2700 is the actual total bandwidth.  

 333 MHz x 8 bytes = 2700 megabytes per second,   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.

DDR And DDR2 DIMM has 240 pins compared to DDR, its has 184 pins. DDR2 is labeled  DDR. 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.   

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 DDR2 DDR3 also has 240 pins, the notches in the DIMMs are in different places cannot have a DDR3 DIMM in a RAM slot made for a DDR2 in fact motherboards are made to support to a certain

Type of memory so you can't mix DDR 1, 2, 3, or 4 on the same motherboard  Example;   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  and  DDR4-4266 PC4-34100 it has an incredible maximum bandwidth of 34,100 megabytes per second Now sometimes there are circumstances where memory data corruption cannot be tolerated   

Servers are meant to be up and running at all times and some servers cannot afford to be offline for any reason.    servers that control financial data, emergency medical data, or government data. These servers cannot go down for any reason and that's   RAM modules have ECC its stands for error-correcting code and what ECC does is it detects if the data was correctly processed by the memory module and makes a correction if it needs to   RAM the module has ECC by counting the number of memory chips on the module.

For more about computer :https://techcj-tech.blogspot.com/2021/08/a-brief-history-of-computer.html

In a standard Non-ECC DIMM, it will have eight memory chips  in an ECC memory module it will have nine memory chips 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 was more stable.  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 an extra precaution to guard against any memory errors.

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