Essentially a patchbay for MIDI signals. Passive patchbays simply present MIDI In and MIDI Out sockets conveniently on a front panel to facilitate patching via patchcords. Active patchbays will generally have MIDI sockets on the rear panel, switches and displays on the front panel, and will also have a memory which allows commonly used patches to be stored. These, in turn, may be triggered by specific MIDI Program Change messages sent to the unit. As all of this requires some processing power, an active patchbay will often perform other functions such as MIDI Merge or MIDI mapping.