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RAM Explained - Random Access Memory

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Oct 02, 2016

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RAM Explained - Random Access Memory
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  • 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 Dims?
  • Dim stands for dual inline memory module [a] Dim is a dual inline module because it has two
  • independent rows of these pins one on each side [a]
  • Dim Memory module has either
  • [168]
  • 184
  • 240 or
  • 288 pins and then the Dim 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 harddrive 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 ones or zeros 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 dims and these dims come in different memory sizes today. They range anywhere [from]
  • 128 megabytes to 32 gigabytes per Dim
  • 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 dims have a [64] [bit] data path which means that they can transfer 64 bits of Data at a time
  • now prior to dims there was an older ram module called a sim and Sims had a
  • [32-bit] [Data] path which means they can transfer [data] at 32 bits at a time
  • So that's why dims are faster than sims because they can transfer twice the amount of data per clock cycle
  • Because Dims transfers 64 bits of Data at a time
  • Compared to sims 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 ones and zeros which is represented by a single bit of data
  • Now there is also the term byte and [eight] bits is equal to one byte
  • so if a memory dim is ready 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 [equals] 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 Megahertz 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 equals 8 so
  • [to] figure out the total bandwidth of PC. 100 you multiply 100 Megahertz times 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 equals
  • 1066 So the Total Bandwidth for PC 1 33 equals
  • 1066 megabytes per second now technically 133 times 8 actually
  • equals
  • 1064 But
  • 1066 is accurate because the actual clock speed is 130
  • 3.3333
  • Times 8 which is rounded off to
  • 1066
  • Another type of memory was called our dram which was developed by [Rambis] inc
  • And they developed the Rim which stands for rambus inline
  • memory module
  • Rims have 184 pins and looks similar to Dims
  • With the exception [that] the bottom notches are located in the center [of] the module
  • In 1999 Rims were breakthrough in the speed of memory
  • But has quickly fallen behind due to the advancement of technology in Dims
  • when our [dream] debuted in 1999 it ran at 800 Megahertz which was considerably faster than
  • Sdram which ran at
  • 133 Megahertz at that time
  • But even though it was a lot faster [than] Sdram our dram only had a two byte wide bus
  • compared to sdram which had an 8 byte wide bus
  • so if you multiply the speed of our dram which was 800 Megahertz
  • Times 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 ramp
  • 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
  • you
  • Ddr. Is 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 dim [labelled] DDR 333 PC
  • 2700 the 333 [is] the clock Speed and the
  • 2700 is the actual total Bandwidth?
  • so 333 Megahertz times 8 bytes
  • Equals 27 hundred 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
  • Ddr to Dim has
  • 240 pins compared to DDR. Which has [one] hundred [and] eighty four pins
  • DDR2 is labeled just like DDR. But with a small difference
  • for example [a] DDR to dim could be labeled DDR2
  • 800 PC to
  • 6400 and the difference is the two right after the DDR and the two 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 Dims 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
  • [Pc] 3
  • [12800]
  • And the fourth Generation of DDR. Sdram is
  • DDR4
  • DDR4 Dimms have
  • 288 pens 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 PC 434 100 which has an incredible maximum Bandwidth of
  • [34,000] 100 megabytes per second
  • Our 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 and a Standard
  • Non-ECC them 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 advanced and technology that has [minimised] 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
  • you

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Description

Here is the RAM that I use in my PC: https://amzn.to/2KqHGwQ
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This is an animated video RAM tutorial. Topics include how RAM works, RAM speed, DRAM, SDRAM, Rambus RDRAM, DDR, DDR2, DDR3, DDR4, and ECC.

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