A picture of the MIT CADR. Rear view of a machine in an entirely normal operational state. These machines did not have rear panels; the card cage for the IO busses is simply exposed, and you can see the cabling to the disk, console, and debug cables. You can see disks to the left, and the edge of the console screen and keyboard.
See also: AI memo 528, May 1979, CADR, By Thomas F. Knight, Jr., David A. Moon, Jack Holloway, Guy L. Steele, Jr.
Pictures courtesy of James Crippen. Thanks also to Chris Stacy for additional comments.