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".

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.

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.

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 code holds 2.2 kilobytes of information.

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 by first compressing it with nvpktool.exe and then converting into BMP images with nedcmake.exe.