EEPROM (Electrically Erasable Programmable read only memory)Programmable Read Only Memory。Is a kind ofPower failureafterdataNot lostMemory chip。 EEPROM can erase the existing information on the computer or special device and reprogram.It is generally used in plug and play.
Chinese name
EEPROM
Foreign name
Electrically Erasable Programmableread only memory
EEPROM (Electrically Erasable Programmableread-only memory）It is a user changeable read-only memory (ROM), which can be erased and reprogrammed (rewritten) by the action of higher than normal voltage.Unlike EPROM chips, EEPROM can be modified without taking it out of the computer.In an EEPROM, the computer can be repeatedly programmed when it is in use, so the life of the EEPROM is a very important design consideration parameter.EEPROM is a special form ofFlash MemoryIts application is usually the voltage in the personal computer to erase and reprogram[1]。
characteristic
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EEPROM,It is generally used for Plug&Play.
It is often used in the interface card to store hardware setting data.
It is also commonly used in "hardware locks" to prevent illegal copies of software.
background knowledge
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EEPROM memory
staymicrocomputerAt the beginning of its development, BIOS was stored in ROM (Read Only Memory,read-only memory）Medium.The internal data of ROM is generated by special methods in the manufacturing process of ROM in the factoryBurnIf the data is entered, the content can only be read and cannot be changed. Once the data is burned, the user can only verify whether the data written is correct and cannot make any changes.If there is any error in the data, you have to discard it and make a new one.ROM is produced on the production line. Because of its high cost, it is generally only used in mass applications.
Due to the inconvenience of ROM manufacturing and upgrading, people later invented PROM (Programmable ROM).There is no data inside the PROM originally made from the factory. Users can use a special programmer to write their own data, but this opportunity is only once. Once written, it cannot be modified. If there is an error, the written chip can only be scrapped.PROM has the same characteristics as ROM, but its cost is higher than that of ROM, and the speed of writing data is faster than that of ROMbatch productionThe speed should be slow, and generally it is only applicable to situations with small requirements or verification before mass production of ROM.
EPROM(Erasable Programmable ROM) chip can be erased and written repeatedly, which solves the problem that PROM chip can only be written once.EPROM chip has an obvious feature. On the front of the ceramic package, there is a glass window through which you can see theIntegrated circuitThe data in the internal chip can be erased by ultraviolet ray shining through the hole, and the EPROM eraser is used to complete the chip erasing operation.Special programmer shall be used for writing data in EPROM, and certain programming voltage must be applied when writing content to the chip (VPP=12~24V, depending on different chip models).The EPROM model starts with 27. For example, 27C020 (8 * 256K) is an EPROM chip with 2M bits capacity.After the EPROM chip writes the data, it should also seal the window with opaque stickers or adhesive tapes to prevent the data from being damaged by the surrounding ultraviolet radiation.[1]
Fundamentals
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Due to the inconvenience of EPROM operation, most of the BIOS ROM chips on the motherboard that came out later used EEPROM (Electrically Erasable Programmable ROM).The erasure of EEPROM does not need the help of other devices. It modifies its content with electronic signals, and uses Byte as the minimum modification unit. It does not need to wash all the data before writing, completely getting rid of the shackles of EPROM Eraser and programmer.When EEPROM writes data, it still needs to use a certain programming voltage. At this time, only the special refresh program provided by the manufacturer can easily rewrite the content. Therefore, it belongs to a dual voltage chip.With the help of the dual voltage characteristics of EEPROM chip, the BIOS can have a good anti-virus function. When upgradingJumperTurn the switch to the "on" position, that is, add the corresponding programming voltage to the chip, and it can be easily upgraded;In normal use, turn the jumper switch to the "off" position to prevent CIH viruses from infectingBIOS chipIllegal modification of.Therefore, many motherboards still use EEPROM as the BIOS chip and as a major feature of their motherboards[1]。
Related terms
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EEPROM related terms:
one
electrically erasable programmable read only memory(EEPROM)
Electrically Erasable Programmable Read Only Memory
