How do Solid-state Drives Store Information?

hard disk drive ogConsidering hard-disk drives have been around since the late 50’s, it’s probably not too crazy to wager that fewer people know how a solid-state drive works than your average hard drive. That said, hardly anyone understands how any of the devices on which they rely actually work, and they don’t take the time to come to terms with that fact either. For those of you who are brave enough to be curious, to take your complete lack of understanding of the world head on by actively attempting to learn where the technology that’s normalized around you came from and why it was invented, here’s a little tidbit about your standard SSD.

Why the Change to Solid-State

The spinning-platter concept of hard disk drives was the a great technological innovation during its time. That said, it was engineered for a device that was about the size of two industrial refrigerators. Its inventors had no way of understanding that what they were making would at some point have more value if it could be fit into a device the size of a deck of cards (or a piece of gum).

Eventually when smaller size did become valuable, people realized that any information storage system that relied on a spinning disk could only be so small; eventually, physical limitations caught up with it. That was part of what prompted creating an information storage device that was composed of all-stationary (solid-state) parts.

Instead of relying on magnetized media stored on spinning plates, SSDs use semiconductor chips built from transistors and other computer chip components. Because they can store information without having access to power, they possess flash memory as opposed to RAM (random-access memory).

semiconductor fabA semiconductor is a solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Silicon is among theĀ  most utilized semiconductor. At semiconductor fabs, integrated circuits are etched into raw silicon wafers, a process which involves photographing the desired circuit pattern on a photosensitive substrate and then chemically etching away the background.

Among flash memory, two other distinctions can be made; NOR and NAND. NAND flash memory involves cells that require fewer wires and can be packed on a chip with greater density, making it the least expensive and more common option in SSDs. NAND chips are generally created at the afore mentioned semiconductor fabs.

Solid-state drives are faster than hard disk drives for a lot of reasons; for one, because they are not composed of moving parts, every cell is accessible at the same speed as every other cell. Being made of stationary parts also allows for reading and writing data to and from the solid-state drive to be faster as well, so not only does the computer have to wait fewer milliseconds for its requests to be serviced, but the solid-state drive can also effectively read and write data faster. Quicker responses (lower latency) plus faster transfer speeds (more bandwidth) mean that an SSD can move more data faster, and with a higher throughput.

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