XPMCK is a music (expressed in MML) compiler kit targeted towards various video game systems. It currently supports the following systems:

Capcom Play System (VGM output only)
ColecoVision
Commodore 64
MSX (KSS output only)
Nintendo Gameboy / Gameboy Color
SEGA Master System
SEGA Game Gear
SEGA Genesis

Besides the compiler and its source code, the kit includes playback libraries for all supported systems, as well as examples and brief documentation.

Changes:

* Added a transpose command.
* Added support for per-note macros.
* Fixed a bug in the handling of [] loops in the Gameboy and C64 playback libraries.
* Fixed a bug that would occur when the initial delay in an @MP macro was zero.
* Fixed some bugs in the compiler which would result in some AY-specific commands being ignored when outputting for the Amstrad CPC.
* Step values for intervals are now automatically given the correct sign by the compiler.

http://jiggawatt.org/muzak/xpmck/