RMT is a cross platform tracker which emulates the "pokey" chip of the Atari XE and XL 8 bit home computers. It can export: (.SAP), (.XEX), and (.ASM) files. RMT can import protracker (.MOD)s, theta music composer songs (.TMC) and has basic midi support.
The "pokey" chip (Pot Keyboard Integrated Circuit) has 4 semi-independent audio channels, each with its own volume and waveform values. RMT can emulate dual pokeys for 8 channels of stereo sound.