Developer Chadwick Wood (Coffeeshopped) has updated his iPad patch editing app Patch Base, adding editors for 2 vintage Roland synths, the D-50 and D-550.
Wood created a video preview:
You can find out more about Patch Base and the new editors at the Coffeeshopped site.
Pricing and Availability
Patch Base is available as a free download from the App Store. Support for individual synths is available as in-app purchases