Why can’t you buy external ram that plugs into a usb like you can for an ssd?
In: Engineering
RAM is very high speed memory that sits very close to the CPU. Think of the CPU as a worker making custom widgets on an assembly line where they need to be constantly supplied with parts. Because they are custom ordered they don’t know which parts they will need for the next widget until it arrives in front of them so the parts must be located very close to them. The time it takes for the part to show up at their station on the assembly line is called latency. RAM is like a coworker in the factory bringing parts to the CPU. If the latency is too high the CPU stalls and sits idle waiting to begin working again until the RAM can provide them with the next thing they need. Although RAM still causes the CPU to stall while it is fetching the next part, it can get it quite quickly because it is located close to the CPU.
Now imagine that we tried to save some money buy not having RAM in the factory and instead just ordered everything online (e.g. from Amazon.) Yes, you can gets things in a day or two but if the CPU can normally make 10 items per day but now has to wait a day for the parts to arrive it will be bottlenecked by the wait time and slow down tremendously.
That’s basically what’s happening inside your PC all the time so there are many layers of storage that are designed to keep a CPU working all the time. The closer the memory the faster it can respond but the more it will cost so you try to find a balance.
The very fast cache memory is right on the chip with the CPU but you only get a few megabytes then next we have RAM where you can have gigabytes followed by solid state drive (SSD) / hard disk drive (HDD) or network storage where you can have terabytes.
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