Hello Grant,
Check out Elm-Chan, they deal with the problem of large SD cards used with weak 8-bit uC:
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This is the bigger brother:
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We don't need much of a file system because the only entity ever reading the cards is QSA, not your end customers on their PCs. So it should be ok if we can't read through a SC card slot in a PC because of a lack of a compatible file system. We could just let it read out through another Open-Vision CF system that's parked in your QC department or via a Labjack that can handle all sorts of serial links.