The RCA SB256 Selectron

The 256-bit production Selectron

Image of the SB256 Selectron

The SB256 is organized as a 2 by 128-bit memory.

photo courtesy Richard O. Endres

The two output sense lines (the electrodes originating within the Faraday cage) are coaxially shielded pins passing through the tube base (above) and mating with a custom socket (below) manufactured by Alden. The coax sockets required a pin recepticle itself floating within the floating shield recepticle. This was required to minimize stress on the glass base from alignment errors in the manufacture of both tube and socket.

Image of black phenolic socket for the SB256