Introduction to Solid State Drives
Solid state drives are a type of storage device used in computers and were launched 35 years ago. Initially known as “solid-state disks”, they were named as such because they were not made up of moving mechanical parts like the hard disk drives instead of memory chips. Their storage material is not similar to that of the previously used devices such as magnetic or optical devices. The materials used for manufacturing SSDs are solid state semiconductors for example, RAM, PRAM or electrically erasable RAM-like non-volatile memory chips. Due to this property they are more resistant to physical shock, run silently and can provide better performance by having better access time and lower latency.

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The solid-state device uses integrated circuit assemblies to store data. They use semiconductor cells for storing data and these devices can vary in their properties depending on the number of bits each cell stores. Single-bit cells are more reliable, durable, and fast compared to 2-bit and 3-bit cells. The earliest introduced flash-based SSD was developed in the 1980s by Zitel as “RAMDisk”. SDDs can be used anywhere, such as in consumer products or being incorporated into graphics cards.
How do SSDs work?
The two components in an SSD are: the flash controller and NAND flash memory chips. This configuration can be optimized to deliver high read/write performance for sequential and random data requests. Different densities are achieved by stacking chips in a grid while manufacturing an SSD.
An SSD reads and writes data to underlying interconnected flash memory made of silicon. SSDs can store data even when they are not connected to a power source as electrical charge is stored in these chips using floating gate transistors (FGTs). Each FGT contains a single bit of data, designated either as a 1 for a charged cell or a 0 if the cell has no electrical charge.
Each data block is accessible at a consistent speed but SSDs can only write to empty blocks. SSDs use three main types of memory, that is, single, multi and triple-level cells.
Single-level cells can hold one bit of data at a time -- a one or zero and are the fastest, most durable and most expensive. Multi-level cells (MLCs) hold two bits of data in each cell. However, MLCs have slower write speeds. Triple-level cells (TLCs) can hold three data bits in a cell.