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Electrically
Erasable
Programmable
Read
Only
Memory.
Basically, you write code or data to the device once then read from it forever after. Unlike the RAM most computers use, this part retains its contents when you remove power from it. This is where the computer or controller goes first thing on powerup or after a reset to get its instructions. Or it is used to hold large amounts of data, like tables or settings, and gets used only once in a while. The erasable part means you can remove and write over the same bytes inside as needed using carefully defined electrical signals. Some memory can be erased at any byte address, at will, then reused, but most of the really large capacity memory parts get erased in large blocks before reuse. Nowadays you can get memory parts holding hundreds of Kilobytes, even megabytes, in 8 pin packages that talk to the ucontroller over a few serial lines. Amazing stuff.
Later!
kenjj
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