quartz window eprom package

# EPROM / EEPROM: the Package That Reveals the History

a quartz window, a density curve, and the erase-time gap that ended both products' run

THE WINDOW THAT GAVE EPROM AWAY ceramic 24-pin DIP quartz window UV lamp, ~253.7nm, ~20-30 min, whole die No in-system erase — chip must be physically removed first A label normally covers the window to block ambient UV in service BITS PER DIE, 1971–1983 bits (log) 1702 2704 2708 27xx era EEPROM entrants 2,048 4,096 8,192

EPROM's whole-die UV erase forced physical removal from the system; EEPROM's byte-level electrical erase worked in-circuit — a service-model difference, not a density one.

Flash then closed the gap from the other direction: block-level electrical erase, fast enough and dense enough to displace both for bulk storage.

THE ERASE-TIME GAP THAT ENDED BOTH PRODUCTS minutes vs. milliseconds — a four-order-of-magnitude difference erase time (log scale) → EPROM ~20–30 min, UV, whole die, chip removed EEPROM ~ms, electrical, byte-level, in-circuit Flash ~ms–s, electrical, block-level — named only | ↑ log scale: each bar's full length, not its visible width, is what to read Vendor timeline, named not mapped to the bars 1971 — Frohman discovers UV erase at Intel 1971–76 — Intel 1702/2704/2708 ship 1978–84 — Xicor, Seeq, Atmel enter EEPROM 1980s–90s — Flash block-erase displaces both floating-gate/tunneling physics: see this site's live NAND Flash article

Invention and business history only — floating-gate mechanism and Fowler-Nordheim tunneling physics live in the NAND Flash article, not here

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