Hardware

Information about GameBoy hardware and programming is extremely hard to find. Most of it is incomplete, uncertain and vague. If you have any new information, PLEASE, email it to me. The following information is mostly based on a document by Pan of Anthrox, Jeff Frohwein's, Pascal Felber's, and my own findings.

GameBoy connector pinouts (not complete)

GameBoy circuitry (not complete)

Full Schematics

These schematics were discovered and plotted by Jeff Frohwein. They are more complete than the ones above.

The MBC schematics are made by Pascal Felber, who also wrote a document on GameBoy cartridges, MBCs, and their programming.

Hardware Projects

The following circuits were developed by Jeff Frohwein, who does quite a lot of hardware hacking on GameBoy.

Jeff's Hardware Setup

GameLink Protocol
An assembly code, a timing diagram, and a circuit for controlling external projects with a GameBoy. You can add as many digital outputs as you want to this port.
GameLink Port I/O
A circuit to control 16 digital outputs and read 16 digital inputs with a GameBoy.
GameLink Port To LPT (Rev.C)
Interface between GameLink serial port and a standard PC parallel port. Because of its non-standard serial format, GameLink can't connect to a serial port. The transistors are required because the parallel port internal pull-up resistors are borderline too low in value.
4MBit EPROM Emulator
This circuit, along with the MBC1 equivalent, can be used to download games or programs to the GameBoy without having to physically move anything. Once download is complete, you can break the connection for independent use.
MBC1 Circuit Equivalent
This circuit can be used instead of Nintendo's MBC1 chip to connect >256kBit ROMs to GameBoy.
Circuit Analyzer (Rev.1)
This circuit captures the address accesses that are made to the game cartridge. It is useful for tracing, not for copying.