Flash memory is a block-erasable, non-volatile semiconductor memory invented by Fujio Masuoka at Toshiba in 1980. It builds on EEPROM but replaces byte-wise erasure with faster block-wise erasure — enabled by floating-gate transistor design. The name 'flash' was coined by colleague Shōji Ariizumi to reflect that speed. Masuoka and colleagues presented NOR flash in 1984 and NAND flash at the 1987 IEDM. Toshiba began marketing flash memory and commercially launched NAND flash — both in 1987. The first published implementation held only 8192 bytes but became the basis for larger-capacity versions. Flash does not support byte-level writes or in-place updates; erasure is all-or-nothing per block. It cannot replace RAM or true EEPROM where fine-grained modification is required. Flash changed how portable devices store firmware and user data, enabling compact, shock-resistant, low-power storage that scales without moving parts — a prerequisite for digital cameras, USB drives, SSDs and smartphones.
Flash memory is a block-erasable, non-volatile semiconductor memory. It solves the problem of needing rewritable storage that retains data without power, while being cheaper and denser than EEPROM.
How it works
Flash memory uses floating-gate transistors to store data non-volatily, erasing content in blocks — not bytes — by applying voltage to remove charge from the gate.
What works
Block-wise erasure works reliably at scale. NOR flash enables fast random reads (suitable for code execution). NAND flash delivers high density and write speed (suitable for mass storage). Toshiba shipped both commercially in 1987.
What does not
It does not support byte-level writes or in-place updates. Erasure is all-or-nothing per block. It cannot replace RAM or true EEPROM where fine-grained modification is required.
What it changes
It changed how portable devices store firmware and user data: enabling compact, shock-resistant, low-power storage that scales without moving parts — a prerequisite for digital cameras, USB drives, SSDs and smartphones.
Is it worth your time
Yes, if you work with embedded systems, storage architecture or semiconductor design: it established the dominant non-volatile memory model for portable and persistent data, but its block-erase constraint remains a hard limit on write endurance and granularity.
