If you want to compile a test ROM get the executables from RGBDS 
(Rednex Gameboy Development System) and unzip them in this directory.

http://www.otakunozoku.com/rednex-gameboy-development-system/

RGBASM.EXE, RGBFIX.EXE, and XLINK.EXE

The batch files in player/multibnk and player/one_bank will use those 
executables to build the ROM

