User`s manual

High Performance Low Cost Embedded Systems
FLASH
The mini2440 is equipped with two types of Flash: one Nor Flash of type SST39VF1601, 2M
bytes memory, and one Nand Flash of type K9F1208, 64M bytes memory. The S3C2440 supports
system boot from either Flash. You can boot systems from either the Nor or the Nand flash by
toggling the S2 switch. In fact most systems only have a Nand Flash. For the sake of users
especially developers we add a Nor Flash, that way, you can have more control over the system.
The Nand Flash doesn’t have address lines. It has dedicated control interfaces connected to CPU. Its
data bus is 8-bit, but this does not necessarily mean the Nand Flash writes or reads slowly. Most USB
drives and SD cards are made of Nand Flash.
The diagram below presents that the Nor Flash has 22 address lines A1-A22 and 16 data lines
connected to CPU. The address starts from A1 implying that the minimum amount of data read/write
is always 2-byte. Based on this diagram, the maximum size of the Nor Flash is 8Mbyte. In our system,
only A1-A20 are active, A21 and A22 that are connected to SST39V1601 are idle.
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