GI20Editor is a software editor for the Roland GI-20 GK-MIDI guitar interface. It can receive a MIDI "bulk dump" containing all the current settings from the device, display and modify any parameter and finally send data back to the unit. It can also save a dump to a file and reload it, thus allowing backups. As far as I know, this is the only editor available for the GI-20.
To receive and send data you need to select your MIDI input and output devices: use the "MIDI/Setup..." command for this. You will need to do this only once if you don't change your setup, since your choices are stored in the "GI20Editor.xml" preferences file.
If you connected your GI-20 through USB, you will tipically see a "Roland GI-20 MIDI IN" input device and a "Roland GI-20 MIDI OUT" output device. If the chosen devices are unavailable when you start GI20Editor, their name will be shown in red instead of green.
Receiving a "bulk dump" is automatic. Use the "MIDI/Upload bulk..." command to send data back to the GI-20. See the GI-20 manual to learn how to send and receive a bulk dump.
Use the "Edit/Copy patch" and "Edit/Paste patch" commands to easily duplicate patches. Use "Edit/Swap patches" to exchange data between them.
You can save and load data using the GI20Editor native format (*.gie) or the standard SysEx dump (*.syx). In this latter case you won't be able to save your comments to the patches, since these are a GI20Editor extension.