Abstract: A non-electronic firewall system may include a first computer isolated from any network, a second computer connected to a network, a display connected to the second computer to display a first image from the second computer, and an image capture device connected to the first computer to capture a second image of a presentation of the display including the first image through a gap. A nonelectric firewall system may additionally or alternatively include a first computer isolated from any network, a second computer connected to a network, a display connected to the first computer to display a first image from the first computer and an image capture device connected to the second computer to capture an image of a presentation on the display including the first image through a gap and to transmit the first image across the network.