>I have no fear of ints.
>My first uC job was decoding barcodes literally while they were coming in
>under the pen.
>Total interrupt job, in fact the int code had to reconfigure the ints to
>get the opposing edges.  I learned a lot, and fast, on that system!

>The best part is decoding a digit in UPC/EAN, from four timings, in five
>comparisons.
>From that, I get direction, parity, and digit.

The best source of info I have for doing this is the original Motorola 6800
Assembly Language Manual (I forget its exact name) which has a section on
barcodes and the theory of scanning a UPC with a wand. As you work through the
book they build a complete POS terminal with example machine code for printer,
keyboard, display and barcode. Its one of those "dont you dare throw it out"
books.

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