This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Collection Item Summary:
This is an unflown Pulse Code Modulation Master Unit, part of the Space Shuttle avionics suite. The PCMMU combines signals from a variety of sources, both analog and digital, on the Shuttle, and translates them into a digital form that is a standard way to transmit or receive information.
NASA transferred this to the Smithsonian in 2016.