Here's how to e-reader works for the most part.

After plugging the E-Reader into the GBA as if it were a cartridge,
turn on your GBA. Then you'll go into some menus and then
goto "SCAN DOT CODE"

Then, what you'll do is scan the card through the barcode reader
thing and it saves the data stored on the card to the memory of the
e-reader. The good thing is, this memory is non-volatile. Now,
most E-Reader programs take up more than just 1 cards worth of data,
emulated NES games normally are 5 cards big. You'll scan card A,
then it will ask for card B, scan card B, then C, etc...

There is a limit to how much of these "programs" you can keep saved
within your E-Reader at one time, but it's nice to be able to save
em and not have to scan em over and over each time you want to play
the same program again...

So, the dot code has to be quite simple, but cracking the code
itself won't be super easy, since it's not written in anything we
can understand directly...

My guess would be to try to find a way to hook up a GBA with an e-
reader loaded inside of it to a computer and try to interpret the
input/output or somethin like that...

-pkmndata

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(just few personal opinion notes on e-reader, no facts)

> There are scanner/printer combos now that do 4800DPI (or claim
> to), and if you give them expensive enough glossy paper the
> print might be clean enough to scan into the e-reader. My
The e-reader itself can't have too much DPI IMHO, it has to be
cheap? Or
not?

> trial and error and be able to publish stuff that way, I'm not
> sure how much encryption they could really be doing on the fly
> with a 16MHz processor.
Why on the fly? The amount of data on the card is very small (few
kb, I
forgot the numbers, but somebody wrote it here in gbadev), it could
be
easily copied into RAM and than decoded and than used. Or am I
missing
some point about the usage of e-cards? (I'm not sure, how they
works, if
the game needs to react instantly on the card, or has time to
decypher
data)
Anyway, I bet the sw side of thing would be broken quite soon, if
somebody would take the care, thw hw side looks harder at the moment.