EEPROM

EEPROM (Electrically Erasable Programmable Read-Only Memory) eliminated the ultraviolet lamp that had made EPROM reprogramming slow and cumbersome. George Perlegos's 1978 Intel 2816 could be erased and rewritten using only electrical signals—a breakthrough that would lead to flash memory and the ubiquitous non-volatile storage of modern electronics.

The adjacent possible built on Dov Frohman's 1971 EPROM invention at Intel. EPROMs stored data in floating-gate transistors that could be programmed electrically but required 15-20 minutes of ultraviolet light exposure to erase. This meant removing chips from circuits, exposing them under UV lamps, then reinstalling them—impractical for devices that needed frequent updates.

The key to electrical erasure was thin oxide. Working at Hughes Microelectronics from 1976 to 1978, Eli Harari demonstrated that a sufficiently thin silicon dioxide layer (under 200 angstroms) would allow electrons to tunnel through when voltage was applied. This Fowler-Nordheim tunneling could erase stored charges without UV light.

George Perlegos brought the thin-oxide technique to Intel. In 1978, he designed the Intel 2816—a 16-kilobit (2K word × 8-bit) EEPROM that could be programmed and erased purely by electrical signals. The underlying structure, publicly introduced in 1980 as FLOTOX (Floating Gate Tunnel Oxide), achieved reliable erase/write cycles up to 10,000 times per byte.

The cascade transformed non-volatile memory. EEPROM enabled devices that could store configuration settings and update them in the field—answering machines could save messages, car computers could store diagnostic data, consumer electronics could retain user preferences. Programmers no longer needed UV erasers on their benches.

Perlegos left Intel in 1981 to found Seeq Technology, which innovated with on-device charge pumps for the high programming voltages. In 1984, he founded Atmel, creating embedded EEPROM devices and the world's first microcontroller with on-chip flash memory. The 2017 Flash Memory Summit Lifetime Achievement Award recognized Perlegos for 'chip design and fabrication process inventions used in EPROM, EEPROM and Flash Memory devices.'

Path dependence shaped memory evolution. EEPROM's byte-by-byte erasability was perfect for configuration storage but slow for bulk data. Toshiba's 1984 flash memory traded byte-level granularity for faster block erasure—a decision that eventually enabled USB drives and solid-state drives. EEPROM remains essential for small-scale configuration storage, while its descendant flash memory stores the world's data.