“ReBoy is a 7 channels 16 steps sample based sequencer for the GameBoy Advance. You need a Gameboy Advance (not tested with Nintendo DS) and a flash-cartridge (I suggest www.flashlinker-shop.de) to flash the program on the cart. As an alternative you can use a GBA-emulator on PC, f.e. VisualBoyAdvance.”
edit: audio example by zabutom