GBA Development/Nintendo e-Reader

Nintendo e-Reader

Once you have written your own new custom GBA program, you could potentially distribute it to other people -- if they have a e-Reader -- in the form of "e-Cards".^[1][2]

The e-Reader scans special cards printed with a "Dot Code". Cards may be swiped in either direction (left or right). When a program comes on two or more cards, the cards do not need to be swiped in any particular order.^[3][4][5]

Tim Schuerewegen was successful in cracking the "dot code" code and was able to turn some homebrew programs into cards, playable on the e-Reader device. Using a special program, one is able to convert program data into a card stripe, and print it onto a piece of paper that can then be scanned and interpreted by the e-Reader.^[6][7]

For example, a homebrew NES game by Snobro, BombSweeper (a Game & Watch title clone), as well as numerous tech demos ("hello world," "Mario sprite," etc.) were made into executable files that could be converted into dot code.

Each card can hold up to two code strips. A long bar code holds 2.2 kilobytes of information.^[8]

A byproduct of the homebrew effort was that a method of "dumping" the data encased in the dot code of e-Cards was discovered. This led to a modified version of the e-Reader ROM image being created that can accept these "dumps" and interpret them for use in an emulator.

Homebrew cards can be created from any NES, z80, or arm game (recommended due to smaller file sizes) by first compressing it with nvpktool.exe and then splitting it into bin files with nedcmaker.exe. The resulting bin files can be imported into the e-Reader game ROM under a hacked version of VisualBoyAdvance, which will also output the raw dot code cards that can be printed with nedcprint.exe.

The more modern way of doing it is by using a program such as WinRAR.

Further reading