If you’ve purchased an SSD or used memory cards for cameras, you’ve 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 non-volatile semiconductor memory called flash memory.
Flash memory was a breakthrough because it allowed fast rewrites and could store data without power. Because it’s solid state, it uses no moving parts, making it sturdy and durable, and it requires less power to operate than conventional magnetic disks. This low power requirement and compact size have made flash memory an ideal solution for portable devices.
According to the Computer History Museum, flash memory gets its name from its ability to erase data quickly, in a “flash.” Old erasable, non-volatile solid-state memory chips (like EPROMs) took minutes (sometimes up to 20 minutes) to erase before they could be written back to. It is this write, erase, and rewrite speed that has made flash memory a convenient replacement for floppy disks or Zip disks in the form of USB drives and traditional hard drives in the form of SSDs.
Flash memory is made up of floating-gate transistors, which store electrons on an insulated gate. 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 returns the transistor to its original state. To do this, an electrical charge is sent through the transistor, which releases the electrons from the gate.
Flash memory comes in three basic formats: NOR, NAND (named after types of logic gates), and EEPROM. Most flash memory today is NAND type because it is the cheapest and generally consumes less power than other types.
Types of flash memory cards
Electronics manufacturers use flash memory in a variety of applications, including smartphone storage, USB flash 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.
In 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 forms of the main flash cards, their launch date and maximum capacity:
- CompactFlash: Launched in 1994 by SanDisk. Available in capacities up to 512 GB, then expanded with CF 5.0.
- SmartMedia: Launched 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.
- Memory Stick: Launched in 1998 by Sony. Available in capacities up to 128MB.
- Secure Digital (SD): Launched in 1999 by SanDisk. Support 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 the CompactFlash Association. Available in capacities up to 4TB.
Many of these card types have been extended with new standards to support higher capacities over time, such as SDHC, SDXC, and MemoryStick Pro cards. Some flash card formats have also been marketed in several sizes, such as miniSD and microSD, which remain compatible with each other thanks to adapters.
Flash memory life
As wonderful as flash memory is, it doesn’t last forever. In fact, it can only be written to so many times before it crashes. However, in 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 around 10 years. However, this may vary depending on the quality of the card and the conditions under which it is used.
Solid state drives generally last longer than flash memory cards because they are designed for more intense and continuous use. When buying an SSD, look for a number of “TBW”, or “terabytes written”. A higher number means the drive can tolerate more data being written and 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 can fail from time to time, so remember to always make backups. Stay safe !