There are sounds for key confirmation and also to signal operator errors.
The Vault uses sounds to tell the operator when operations succeed or fail.
All these sounds are now generated by the SGI.
The stereo signal from the SGI needs to run out to the operators console, to a pair of small powered speakers.
On the O2 analog video card there are two phono sockets for audio.
On the O2 digital video card there is a mini stereo jack socket for
audio.
On the Indy this comes from a mini stereo jack socket.
The old mono sounds from the Pogle console are no longer operational.