What is Flash Storage?

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If you’ve bought an SSD or used memory cards for cameras, you’ll probably come across the term “flash memory”. But what is flash memory and how does it work? We will explain 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 robust and durable, and it required less power to operate than conventional magnetic disk solutions. This low power consumption and compact size have made flash memory ideal for portable devices.

According to the Computer History Museum, flash memory earned his name because of its ability to erase data quickly, in a “flash”. Old erasable, non-volatile solid-state memory chips (such as EPROM) took a few minutes (sometimes up to 20 minutes) to erase before overwriting can occur. It is 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 drives and traditional hard drives in the form of SSDs.

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How does flash memory work?

Flash memory is made up of floating-gate transistors, which store electrons on a gate isolated. The grid is electrically charged to hold 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 electrons from the gate.

An illustration of circuits or circuits in blue
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Flash memory is available in three basic formats: NOR, NAND (named after the types of logic gates), and EEPROM. Most flash memory today is of the NAND type because they are the least expensive and generally consume less power than other types.

Types of flash memory cards

Different types of flash memory cards
Different types of flash memory cards. Benj Edwards

Electronics manufacturers use flash memory in a variety of applications, including smartphone storage, USB flash drives, and solid-state drives. 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, ordinary computer owners most commonly used flash memory in the form of removable flash media cards, often inserted into digital cameras and PDAs. Here are some major flash media card shapes, including their date of introduction and maximum capacities:

  • compact flash: Introduced in 1994 by SanDisk. Available in capacities up to 512 GB, later expanded with CF 5.0.
  • Smart Media: Introduced in 1995 by Toshiba. The maximum capacity was 128 MB.
  • MultiMediaCard (MMC): Introduced in 1997 by SanDisk and Siemens. Available in capacities up to 512 GB.
  • USB key: Introduced in 1998 by Sony. Available in capacities up to 128MB.
  • Secure digital (SOUTH DAKOTA): Introduced in 1999 by SanDisk. Supports up to 2 GB, extended formats 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 CompactFlash Association. Available in capacities up to 4TB.

Many of these types of media cards have been extended with new standards to support higher capacities over time, such as SDHC, SDXC, and MemoryStick Pro. Some flash media card formats also come in multiple sizes, such as miniSD and microSD, which remain compatible with each other through the use of adapters.

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Flash memory life

As wonderful as flash memory is, it doesn’t last forever. In fact, it can only be written so many times before it fails. However, in modern flash devices, the number of write cycles is quite large.

According to SD Association FAQs, 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 under which it is used.

SSDs generally last longer than flash memory cards because they are designed for heavier continuous use. When buying 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 it will generally last longer. If you’re a typical home computer user, you shouldn’t have to worry about an SSD crashing due to too many writes. But SSDs occasionally fail randomly, so remember to always keep backups. Stay safe there!

RELATED: What does “TBW” mean for SSDs?

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