AT91SAM7S256 Memory Mapping - Internal Flash 256K or 1M?

Discussion about SAM7 Series and ARM7TDMI based products.

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AT91SAM7S256 Memory Mapping - Internal Flash 256K or 1M?

Sat Apr 22, 2017 5:36 pm

I am a beginner trying to learn to program AT91SAM7S256. I am a bit confused since it is supposed to have 256K of internal flash, but the figure below (from datasheet) indicates the size is "1 M Bytes":
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Re: AT91SAM7S256 Memory Mapping - Internal Flash 256K or 1M?

Tue Apr 25, 2017 12:42 am

Apparently you're conflating two different memory sizes.

The figure is for the memory map which has memory address assignments to memory regions, and are the allocated address spaces.
There may not be actual memory at those address, e.g. there's "undefined areas" that have addresses but no installed memory.
You've pointed out that 1 MB of address space is allocated to internal flash.

You mention that there's 256KB of internal flash.
That would be flash memory that is actually installed and usable.

As long as the size of installed memory is less than or equal to the allocated address space, there's no issue.
There's no requirement that the installed memory size must equal the allocated address space.
The size of the allocated address space cannot be used as the size of installed memory.


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