The IAC (Inter-Application Communication) driver provides a set of virtual MIDI input and output ports that can be used to pipe MIDI data between applications of a computer.
Most of the time you don't need it because OSCulator already provides a virtual MIDI output “OSCulator Out” and one virtual MIDI input “OSCulator In (xxxx)” 1) for each window. However some applications are not compatible, and the IAC driver needs to be used.
To activate it, launch Audio MIDI Setup (found in /Applications/Utilities), then show the MIDI Window (from the Window menu), then double click the IAC icon, and in the new window, click “Device is online”.
Once the IAC driver is activated, you need to tell OSCulator to receive or send data from/to the IAC driver. To do this, we will activate the IAC driver in the list of MIDI inputs and outputs. Go to OSCulator, open the Parameters window, click on the I/O tab, and in the MIDI Input drop-down menu, activate the “IAC Driver Bus 1” to the list. To send data from OSCulator to the IAC driver, do the same operation using the MIDI Output drop-down menu.