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What is the basic difference between a EEPROM and Flash Memory, dont say EEPROM needs a extra select transistor

EEPROM is a type of flash memory, in that it can be written to and erased without having to use a specialized device. Evil saltine 12:40, 20 Dec 2003 (UTC)
Flash memory is a type of EEPROM, you mean. It describes this in the text now. — Omegatron 21:22, 14 January 2006 (UTC)
Flash memory erase can only be done in blocks or complete chip. Single byte write is possible with EEPROM. SPI EEPROM's from e.g. Atmel or Microchip has typically the possibility to write more bytes faster with "page" write -which actually come close to a "block". Now there are pin-compatible EEPROM and flash with SPI. Historically these two types of memory were more different, e.g. flash memory could not be written to as many times as EEPROM. Flash memory is a relatively new technology when compared to EEPROM. --Nordby73 00:13, 1 February 2006 (UTC)

Ok, I'm wondering why EEPROM is called ROM. I think it's because EEPROM depends on an electrical process to change the bits, rather than an electronic one. Can someone please confirm this and/or post the clarification? Mang 00:42, 4 March 2006 (UTC)

For the same reasson that EPROM is called that. It's intended for read-mostly applications, and writing it is more difficult than with a RAM (taking longer and/or requiring special voltages), so it is conceptually closer in function to a ROM than to a RAM. --Brouhaha 06:23, 4 March 2006 (UTC)
The name comes from the history of this products. EPROMs required a UV light source the get erased, something not typically found inside a computer (well, some case modders might disagree now...). Erasing typically took several minutes. EPROMs were typically removed from the board before they got reprogrammed. They were used instead of ROMs when frequent firmware updates were to be expected (their precedessors, the PROMs, were writeable only once). EEPROMs were the successors of EPROMs, allowing erasure of the chip with electricity instead of UV light. Early EEPROMs could only completely ersae the chip, the they were no RAM (as there was no "Randnom Access", only "full erase and reprogram"). They typically required programming voltages which were not available in most target platforms, and the need for a full reprogram cycle even if only a single bit was changed meant write access times of several minutes. Later on, some of these issues got fixed (lower programminmg voltages and the ability to erase less a full chip). Thatnks to this, write access times are now down to a few milliseconds. Milli, not micro! Compare that to a typical RAM chip where write access time is specified in nanoseconds (and that since the 1970's). --Klaws 13:06, 5 June 2007 (UTC)

I added the following phrase in the leading section. Cafeduke (talk) 07:49, 13 March 2018 (UTC) EEPROM typically allows a byte (or a word) to be erased, and re-written individually, while typical flash memory erase some region in the device at once.

More cleanup?[edit]

I think this article could have separate chapters covering memory mapped (adress and data bus), serial EEPROM and history. I'm not into the old history parts myself, even though I've also been working on products with memory mapped EPROM's. --Nordby73 00:26, 1 February 2006 (UTC)

I attempted to do some cleanup now. The list of manufacturers is far from complete, and should contain at least 8-10 companies. Also, the operation of parallel bus devices is completely missing. That part of the article should at least deserve a few sentences. --Nordby73 18:45, 4 March 2006 (UTC)
I drastically modified the history section because it was obviously strange, I think. A lot of citation was needed to figure out the truth. Cafeduke (talk) 07:53, 13 March 2018 (UTC)

In first line the def states (configuation) data.[edit]

In first line the def states (configuation) data.

True for PCs. But lots of EEPROM is in embedded systems where it stores entire programs, stored tables of data and logged data. It seems to me that the "configuration" part is a PC-centric view of EEPROMS. I'm guessing we each own several embedded systems for each PC we own and thus there would be more EEPROM used for programs and data then for configuration.

Thanks, John

Yes. EEPROMs are embedded into many microcontrollers for such as Key-less entry of the car, and smart cards (with contact or contact-less IC-cards, including credit and SIM). In this meaning, this article needs improvements. Cafeduke (talk) 07:59, 13 March 2018 (UTC)


EE = Electrically Erasable, EA = Electrically Alterable. EAROM/EAPROM devices were once marketed as superior to EEPROMs, since EEPROMs could only be erased completely, while EAROMs/EAPROMs offered a more granular control about which regions get erased. This is history, of course. Nowadays, the word EEPROM includes devices where individual bytes can be erased. --Klaws 12:53, 5 June 2007 (UTC)

EAROM redirects to the EEPROM article, but EAROM is not mentioned at all! -- (talk) 17:24, 7 December 2008 (UTC)

I came here looking for for an understanding of EEPROM structuer and did not find it. I would have liked to see a paragraph describing how EEPROM works at the cell level. Perhaps something like, "An EEPROMS cell consists of 3 transistors configured as ..." along with a schematic of a cell and a generalized chip schematic. —Preceding unsigned comment added by (talk) 21:02, 9 August 2009 (UTC)

I also noticed EAROM redirects there with no mention to it. I just added an historical reference to EAROM in the solid-state drive article. If someone does not add some information I may take a shot at it shortly when I get a chance.§ Music Sorter § (talk) 04:09, 20 June 2011 (UTC)

Not accurate and/or totally wrong.[edit]

Article says this: "However, an EEPROM chip has to be erased and reprogrammed in its entirety, not selectively."

I think this is misleading, if not incorrect. EPROMs had this limitation. The EEPROM limitation is that your read/write/erase operations *must* occur one byte at a time, rather than in larger blocks; making EEPROMS slower. Although modern EEPROMS allow page write operations. (talk) 01:44, 8 September 2010 (UTC)

Fixed (talk) 01:57, 8 September 2010 (UTC)

American Invention?[edit]

Why is this tagged as an American Invention? According to the article, EEPROM was first studied, created, and patented in Japan, thus making it a Japanese invention. I'm going to change the tag to Japanese Inventions unless someone can prove it should in fact be tagged as an American invention. — Preceding unsigned comment added by HBBorges (talkcontribs) 23:09, 6 May 2018 (UTC)