What is flash storage?

If you’ve been shopping for an SSD or using memory cards for cameras, you’ve probably come across the term “flash memory.” But what is flash memory and how does it work? We explain it to you.

The origins of flash memory

In the early 1980s, a team of Toshiba engineers led by Dr. Fujio Masuoka invented a new type of nonvolatile semiconductor memory called flash memory.

Flash memory represented a breakthrough because it allowed fast rewrites and could store data without power. Being solid-state, it used no moving parts, so it was strong and durable, and required less power to run than conventional magnetic disk solutions. This lower power requirement, and its compact size, made flash memory ideal for portable devices.

According to the Computer History Museum, Flash memory got its name from its ability to quickly erase data, in a “flash.” Earlier non-volatile, erasable solid-state memory chips (such as EPROMs) took minutes (sometimes up to 20 minutes) to erase before it could be rewritten. It was this speed of writing, erasing, and rewriting that later made flash memory a practical replacement for floppy disks or Zip disks in the form of USB sticks and traditional hard drives in the form of SSDs.

RELATED: Even 25 years later, the Iomega Zip is unforgettable

How does flash memory work?

Flash memory is made up of floating gate transistors, which store electrons in an isolated gate. The gate is electrically charged to contain the electrons, and this charge can be used to represent data. Flash memory can be erased and rewritten because electrons can be removed from the floating gate, which resets the transistor to its original state. This is done by sending an electrical charge through the transistor, which releases the gate electrons.

Flash memory comes in three basic formats: NOR, NAND (named after the types of logic gates), and EEPROM. Today, most flash memory is of the NAND type because it is the least expensive and generally consumes less power than the other types.

Types of flash memory cards

Electronics manufacturers use flash memory in a variety of applications, including smartphone storage, thumb drives, and solid-state drives (SSDs). SSDs are becoming increasingly popular as a replacement for traditional hard drives. SSDs are faster, more durable, and consume less power than spinning disk hard drives.

Throughout the 1990s and 2000s, flash memory was most commonly used by ordinary computer owners in the form of removable flash cards, often inserted into digital cameras and PDAs. Here are some shapes of the major flash media cards, including when they were introduced and their maximum capacities:

• Compact flash: Introduced in 1994 by SanDisk. Available in capacities up to 512GB, later expanded with CF 5.0.
• Smart media: Introduced in 1995 by Toshiba. The maximum capacity was 128 MB.
• Multimedia Card (MMC): Introduced in 1997 by SanDisk and Siemens. Available in capacities up to 512 GB.
• Memory card: Introduced in 1998 by Sony. Available in capacities up to 128 MB.
• Digital Security (SD): Introduced in 1999 by SanDisk. Supports up to 2 GB, extended format support up to 128 TB theoretical.
• xD-Picture Card: Introduced in 2002 by Olympus and Fujifilm. Available in capacities up to 2 GB.
• XQD card: Introduced in 2011 by Sony. Available in data capacities up to 4TB.
• CFexpress: Introduced in 2017 by the CompactFlash Association. Available in capacities up to 4TB.

Several of these media card types have been expanded with new standards to support higher capacities over time, such as SDHC, SDXC, and MemoryStick Pro. Some flash media card formats have also shipped in various sizes, such as miniSD and microSD, they are still compatible. each other by using adapters.

RELATED: What SD card do I need for my camera?

Flash Memory Life

As wonderful as flash memory is, it doesn’t have an unlimited shelf life. In fact, it can only be written a certain number of times before it fails. However, on modern flash devices, the number of write cycles is quite large.

According to the SD Association FAQ, the typical lifespan of a consumer SD card is about 10 years. However, this may vary depending on the quality of the card and the conditions in which it is used.

SSDs typically last longer than flash memory cards because they are designed for more intense continuous use. When shopping for an SSD, look for a “TBW” or “terbabytes written” number. A higher number means the drive can tolerate more data being written over time and will generally last longer. If you’re a typical home computer user, you shouldn’t have to worry about SSD failure due to too many writes. But SSDs randomly fail from time to time, so remember to always keep backups. Stay safe out there!

RELATED: What does “TBW” mean for SSDs?