Difference Between EEPROM and Flash

EEPROM vs Flash

Flash is a very popular term when it comes to storage media as it is used by portable devices like phones, tablets, and media players. Flash actually is an offspring of EEPROM, which stands for Electrically Erasable Programmable Read-Only Memory. The main difference between EEPROM and Flash is the type of logic gates that they use. While EEPROM uses the faster NOR (a combination of Not and OR), Flash uses the slower NAND (Not and AND) type. The NOR type is a lot faster than the NAND type but there is the matter of affordability as the former is significantly more expensive than the NAND type.

Another advantage of EEPROM over Flash is in how you can access and erase the stored data. EEPROM can access and erase the data byte-wise or a byte at a time. In comparison, Flash can only do so block-wise. In order to simplify the whole thing, individual bytes are grouped into a smaller number of blocks, which can have thousands of bytes in each block. This is a bit problematic when you only want to read or write to a single byte at a time; which is what’s typically needed in executing the code of a program. This is a reason why Flash cannot be used in electronic circuits that require byte-wise access to data. Data in Flash can also be executed, but it needs to be read as a whole and loaded into RAM beforehand.

EEPROM was designed to be read a lot more than it is written. This is in-line with programming for electronic circuits where you write to the chip a number of times while testing the program. Then, it is stored for good, only to be read every time the data is needed. This is not very suitable for storage media where data is routinely written and read.

In typical use, Flash is used mainly to refer to storage media and can range anywhere from a GB to hundreds of GB. In contrast, EEPROM is usually reserved for permanent code storage in electronic chips. Typical values range from kilobytes to a couple of megabytes.

Summary:

1.Flash is just one type of EEPROM
2.Flash uses NAND type memory while EEPROM uses NOR type
3.Flash is block-wise erasable while EEPROM is byte-wise erasable
4.Flash is constantly rewritten while other EEPROMs are seldom rewritten
5.Flash is when large amounts are needed while EEPROM is used when only small amounts are needed

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