Anatomy of RAM

poohbear

Posts: 682   +608
Thank you for this article and for this series!!! So informative and absolutely love it as a solid refresher, especially the details!

Can't believe that storage (HDD/SSD) has 256mb of RAM now... in the 90s, a PC had 4mb of RAM for the entire system...can you imagine storage devices having 16GB RAM for themselves some 25 years from now??
 

neeyik

Posts: 1,881   +2,207
Staff member
If you'd like to see some specific that you're interested in seeing chopped up and analyzed, just let us know! :)

RAM levels on storage varies quite a bit, but a brief search suggests the following pattern:

512 MB of RAM = 14 TB HDDs
256 MB = 2 TB to 16 TB
128 MB = 500 GB to 8 TB
64 MB = 250 GB to 6 TB
32 MB = 160 GB to 4 TB

There's even more RAM on SSDs, though:

4 GB of RAM = 4 TB SSDs
2 GB = 2 TB
1 GB = 512 GB to 1 TB
512 MB = 128 GB to 2 TB
256 MB = 120 GB to 960 GB
128 MB = 64 GB to 1 TB
64 MB = 60 GB to 240 GB
32 MB = 60 GB to 120 GB

So the rate of expansion is pretty slow on HDDs, but it's ballooned on SSDs - this is because NAND flash aren't very quick, takes place in blocks (so small data writes have to be buffered until a block is full), and the memory cells wear away with every write. So lots of DRAM helps here, as data can be preloaded, small data packets held ready to put on, or just kept to one side to reduce the wear.
 

jpuroila

Posts: 390   +241
If you'd like to see some specific that you're interested in seeing chopped up and analyzed, just let us know! :)

RAM levels on storage varies quite a bit, but a brief search suggests the following pattern:

512 MB of RAM = 14 TB HDDs
256 MB = 2 TB to 16 TB
128 MB = 500 GB to 8 TB
64 MB = 250 GB to 6 TB
32 MB = 160 GB to 4 TB

There's even more RAM on SSDs, though:

4 GB of RAM = 4 TB SSDs
2 GB = 2 TB
1 GB = 512 GB to 1 TB
512 MB = 128 GB to 2 TB
256 MB = 120 GB to 960 GB
128 MB = 64 GB to 1 TB
64 MB = 60 GB to 240 GB
32 MB = 60 GB to 120 GB

So the rate of expansion is pretty slow on HDDs, but it's ballooned on SSDs - this is because NAND flash aren't very quick, takes place in blocks (so small data writes have to be buffered until a block is full), and the memory cells wear away with every write. So lots of DRAM helps here, as data can be preloaded, small data packets held ready to put on, or just kept to one side to reduce the wear.

I feel like it would be prudent to mention that SMR(shingled magnetic record) hard drives typically have more RAM. So if you see a HDD with high RAM capacity, you should probably avoid it.
 

daimag

Posts: 18   +3
At the bottom of the RAM kit right above the electrical contacts, there are tiny chips aligned nicely in one line. What are those chips for?
 

neeyik

Posts: 1,881   +2,207
Staff member
They're resistor arrays, like this:


They're required to ensure that the voltage on the pins are correctly 'high' or 'low., with regards to the voltage across them (I.e. fully 0 or 1). If you're interested in reading some more about this, then the following article on pull-up/pull-down circuits should help:

 
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Markoni35

Posts: 1,318   +535
So much technology in so little space and at so low price. People don't even appreciate it. They ask "why is that so expensive" even if it's not.

But they don't complain when they pay for some overpriced medical crap, like a plastic tube that costs more than 4 GB of RAM. Because they think "oh, it's medicine, it must be expensive". Because in medicine everything is expensive, as you can extort more money from dying people.

And that's why computers and cellphones are so advanced, and advance so fast, while medicine is so backwards, so expensive and advances at the snail speed. Technological advance is inversely proportional to the level of extortion.
 

neeyik

Posts: 1,881   +2,207
Staff member
You're quite right - I must have been thinking about their flash memory, at the time of writing. They used to, of course, but so did many others.