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Definition: SSD


(Solid State Drive) An all-electronic, non-volatile storage drive. SSDs are the primary storage in mobile devices and are increasingly used as an alternative to hard disks in desktop and laptop computers. Introduced in the late 1990s, SSDs are faster than hard disks because there is no moving read/write head (zero latency).

Comprising NAND flash memory chips, SSDs are available in multi-terabyte capacities. Although more expensive than hard disks, they are generally more reliable and offer greater protection in hostile environments. In addition, SSDs use less power and are not affected by magnets. See flash memory.

In time, there will only be solid state storage, and spinning disk platters will be as obsolete as the punch card. See disk on module and garbage collection.

Much More Complex Than Hard Drives
Flash memory does wear out, and SSDs distribute the writes evenly to all the sectors. A great amount of storage management takes place within the drive itself to ensure that sectors are not erased and written too many times.

Hybrid Drive (SSD and Disk)
Hybrid drives, such as the Fusion Drive in Macs, combine an SSD with a hard disk (see solid state hybrid drive and Fusion Drive).




Hard Drive Replacement Kits
This Kingston kit includes everything necessary to replace a desktop computer's hard drive with an SSD. Kits for laptops include an external case for the old drive while it is being cloned to the SSD. (Image courtesy of Kingston Technology Corporation, www.kingston.com)







Less Costly Every Year
In 2014, a 500GB SSD at USD $349.99 was considerably less expensive than SSDs only a few years prior. However, by 2020, a 500GB SSD cost less than $100. (Images courtesy of Micro Center, www.microcenter.com)








RAM-Based Storage
These earlier products used 4GB of RAM as solid state storage and had battery backup. The MegaRAM (top) also included a hard drive. In the case of power failure, the contents of RAM was quickly copied to the drive. The GIGABYTE i-RAM (bottom) plugged into the PC's motherboard. See nvSRAM and BBSRAM. (Image courtesy of Imperial Technology, Inc.)






The First SSD
In 1977, this Dataram module tied eight magnetic core circuit boards together to make the first solid state disk. It held a whopping two megabytes. See core storage. (Image courtesy of Dataram Corporation, www.dataram.com)






Early SSDs on PC Cards
Minuscule by today's standards (capacities shown are in megabytes), these FLASHDISKs added storage to early laptops. Shown here with a CompactFlash card (upper left) for size comparison, they plugged into a PCMCIA slot (see PC Card). (Image courtesy of SanDisk Corporation, www.sandisk.com)