This is a "hello world"-type project, for a Game Boy DMG to connect to a Microchip Uno32 via SPI.
Install the mcb32 environment (found here) by following provided instructions.
Enter the mcb32 environment and in the hello_spi directory, run;
$ make and $ make install to flash it to the Uno32 board.
Install the GBDK environment from here (this fork for OSX works for me) by following provided instructions. Don't forget to skim through, and fix, the issues reported if you go with the OSX fork.
In the hello_slave directory, run;
$ lcc hello_slave.c -o hello_slave.gb
or whatever you wish to name your output .gb-image.
For copyrights etc, see file COPYING.