---

Contents

• What is Inside GameBoy?
• How to Develop Software for GameBoy?
• Hardware Schematics
• Programming Information
• US Patents Related to GameBoy

Resources

• Development FTP site
• Technical Page by Jeff Frohwein
• Technical Info by Pan of Anthrox
  
• Cartridge Reader by P. Felber
• Cartridge Reader by Yvan Rivard
• Information on GB Cartridges by P. Felber
• Charset Editor by David Dahl

ftp://ftp.komkon.org/pub/GameBoy/Tech/
http://hiwaay.net/~jfrohwei/gameboy/

Following is a little description of some of the tools.

Hardware tools

SmartCard copier by the National Console Support allows to upload the code into a special 512kB flash-ROM card able to store up to 4 different cartridges. It is also able to download the code from cartridges into a PC.

Other two copiers are designed by P. Felber and Yvan Rivard. Pascal's version is more advanced than Yvan's, but the functions are basicallly the same. Both copiers plug into a Centronix parallel port and allow downloading the cartridge code into files.

Logical analyzers allowing to trace various signals in GameBoy circuitry are also very useful for hacking. Jeff Frohwein came up with a circuit of a GameBoy-oriented logical analyzer, as well as with a 4MBit EPROM emulator allowing to download and run the code on a real GameBoy. You can get Jeff's designs off his WWW page, or off the Hardware Info page on this site.

Disassemblers

To be written

Assemblers

The best assembly development environment for GameBoy so far is the Advanced GameBoy IDE being developed by Yvan Rivard. His MSDOS-based application includes an editor and an assembler integrated into a single program with Borland-style interface. The project is in the alpha stage of development though.

Another assembler is written by Jeff Frohwein. It is based on TASM, a retargetable assembler package, distributed on the shareware basis.

Emulators

There are several GameBoy emulators which can be used to debug a program without downloading it into a real machine. The Virtual GameBoy is a multiplatform emulator, written in C. It works on Unix, Macs, PCs, and any other machines for which ports are made. It is probably the most accurate emulator at this moment, but because of its C nature, it is quite slow. The Unix version has a builtin debugger.

GBSim by Jens Restemeier is another emulator which can be very useful for debugging. It is an MSDOS-only application, written in 80x86 assembly. As result, it is quite fast, and has an excellent builtin debugger. Emulation is less precise than in VGB though.