The RCA Selectron -- 9-bit prototypes
These two devices are tentatively identified as prototypes referred to as Selectrons "No. 13" and "No. 14" in laboratory notebooks. The first assembly of these test platforms into the two-inch glass envelopes is late 1946.
Photo courtesy Jerry Vanicek
A page from the notebook of Paul Herkart showing shop drawings of some of the internal electrodes.
Photo courtesy David Sarnoff Library