SD Addressing

Does anyone here understand how block addressing addressing works on SD (secure digital) cards? I have a card that is FAT16.... and I can initialized the card with my HC11, and can read 512 byte blocks of data from it... however I can't understand how the addresses I'm using work.

It seems that no addresses will work untill address 0x200.... then only multiples of 0x200 will work after that. This makes some sense I guess, as 0x200 is 512 in decimal... so I guess I'm addressing blocks of 512 bytes? But the confusion comes in when I try to look at my SD card in HEX on my computer... the offsets don't seem to match up and I'm unable to figure out how to get to a certain offset in the card from the HC11. For instance, I know that a text file is stored starting at 0x6A00 .

Anyone have some hints for me on this? I've never done any programming with FAT's so maybe it's something universal to that and not specific to SD cards.

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Nevermind, I was looking at the card as a logical disk on my computer, which makes 0x00 the start address of the logical drive, and not the physical disk... I found a hex editor, WinHex that let's you look at it as a pysical disk as well.

Take a look at this discussion for some really good information


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