PC-1600x Firmware versions 2.1 - had some small fixes over 2.0. Not documented as well as latter ones, so you might want to update if you have 2.0. 2.2 - Yamaha-style checksums supported in sysex strings (not just Roland). 2.3 - (yes, the current version is 2.3!) added a version request message so computer editors could "ask" the unit which software version it has. It also fixed the scene receive MIDI message to take all 100 scenes and not just the first 50. It also fixed the MIDI maps to be able to point to all the scenes. (NOTE: most users don't need anything past 2.1) John Fera Peavey Digital Engineering July 26, 2007