Along with editing patch parameters within a Sysex file, the D50 Librarian also supports the editing of a patch within the D-50/D-550 in real-time so that you can hear the difference as you edit the patch.

There are two built-in real-time editors:

The VPG-1000 is a virtual version of the PG-1000 MIDI controller that was released back with the original D-50 and D-550 as a means of editing patch parameters in real-time.  It made the editing of patches far easier than via the built in menus.

This version faithfully recreates the original PG-1000 as well as offering a few new enhancements

An alternative real-time editor to the VPG-1000 which allows more parameters to be edited as well as extra editing facilities.  It uses the same graphical user interface as found on the Sysex file window: