Flash memory and eMMC are the two most common non-volatile memory found on embedded systems.
Lets start with Flash - There are two types of them:
1) NOR Flash - Byte addressable (Read a byte, Write a byte (only flip bit:1s to 0s but not vice versa), Erase a sector/block to set all the bits to 1)
2) NAND Flash - Block addressable (Read/Write one block - typically one block is read in to memory before individual bytes in the block can be accessed)
Both types are connected to the system address bus, i.e. they are memory mapped and can be accessed by referencing their memory address.
eMMC:
Embedded Multimedia Controller is basically Flash memory bundled along with a controller. The flash memory can be accessed only via the controller using the eMMC protocol.
Lets start with Flash - There are two types of them:
1) NOR Flash - Byte addressable (Read a byte, Write a byte (only flip bit:1s to 0s but not vice versa), Erase a sector/block to set all the bits to 1)
2) NAND Flash - Block addressable (Read/Write one block - typically one block is read in to memory before individual bytes in the block can be accessed)
Both types are connected to the system address bus, i.e. they are memory mapped and can be accessed by referencing their memory address.
eMMC:
Embedded Multimedia Controller is basically Flash memory bundled along with a controller. The flash memory can be accessed only via the controller using the eMMC protocol.
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