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Definition: SSD

(Solid State Drive) An SSD is an all-electronic non-volatile storage device that is an alternative to, and is increasingly replacing, hard disks. Employed in myriad products, including mobile devices, iPods, cameras, laptops and desktop computers, SSDs are faster than hard disks because there is zero latency (no read/write head to move). They are also more rugged and reliable and offer greater protection in hostile environments. In addition, SSDs use less power and are not affected by magnets.

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

Mostly Flash Memory
SSDs are made of flash memory chips 99% of the time. However, for the absolute fastest storage speed obtainable, there are SSDs that use volatile RAM chips backed up by non-volatile storage in case of power failure (see nvSRAM and BBSRAM).

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. Laptop kits include an external case for holding the old drive while it is cloned to the SSD. (Image courtesy of Kingston Technology Corporation, www.kingston.com)

Less Costly Every Year
In 2014, 500GB at USD $349.99 was considerably less expensive than SSDs only a few years prior. However, by 2019, 500GB cost less than a hundred. (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 SSD PC Cards
Minuscule in capacity by today's standards, these SanDisk 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)