Korg iMS-20 1.0.0
the author of this app says:
KORG iMS-20 is an analog synth studio; a complete recreation of the Korg MS-20 analog synth, an analog sequencer, a drum machine, a mixer, and even Korg's Kaoss Pad technology. Plus, you can share your songs online via the SoundCloud network
Compatible with iPad. Requires iOS 3.2 or later.