{
  "slug": "eeprom",
  "term": "EEPROM",
  "aliases": [
    "Electrically erasable programmable read-only memory"
  ],
  "definition": "EEPROM is electrically erasable nonvolatile memory commonly used for fine-grained updates to persistent configuration and application data.",
  "note": "A standalone serial EEPROM can expose byte updates without a separate host erase command; this does not eliminate internal erase/write work. In the Microchip 24XX256 family, even short writes refresh the rest of the page, so endurance is specified per page. [c1]\n\nIts 64-byte page-write boundary is an address boundary, not just a payload-size limit: crossing it wraps within the same page. For an accepted, unprotected write, STOP starts the internal write cycle; ACK polling then tests readiness. With write protection asserted, the device still acknowledges the command but does not write. WP is sampled at STOP; asserting it afterward does not cancel an internal write cycle already started. Read back the intended locations when verifying an update. [c1]\n\nThese command rules describe the named family, not every EEPROM. Byte access, page wear and application-record consistency are separate design questions.",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "Command acknowledgment alone does not establish that the requested value was stored.",
      "citationIds": [
        "c1"
      ]
    }
  ],
  "related": [
    "eeprom-emulation",
    "nor-flash",
    "solid-state-media",
    "program-erase-cycle"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "c1",
      "title": "Microchip. 24AA256/24LC256/24FC256, DS20001203Y (2022), sections 6.1-6.3 and 7, pages 11-12: byte/page writes, page refresh, protection and acknowledge polling.",
      "url": "https://ww1.microchip.com/downloads/aemDocuments/documents/MPD/ProductDocuments/DataSheets/24AA256-24LC256-24FC256-256K-I2C-Serial-EEPROM-DS20001203.pdf",
      "accessed": "2026-10-20"
    }
  ],
  "updated": "2026-10-20",
  "provenance": [
    "Source review; no hardware test or power-interruption experiment. No atomic multi-byte update guarantee is inferred."
  ]
}