that bit contained a charge, the electrons would be pushed off the dielectric and read as a brief pulse of current in the signal plate. No such pulse meant that the dielectric must not have held a charge. The smaller capacity 256-bit (128 by 2 bits) "production" device was in a similar vacuum-tube envelope. It was built with two storage arrays of discrete "eyelets" on a rectangular plate, separated by a row of eight cathodes. The pin count was reduced from 44 for the 4096-bit device down to 31 pins and two coaxial signal output connectors. This version included visible green phosphors in each eyelet so that the bit status could also be read by eye. Patents Cylindrical 4096-bit Selectron Planar 256-bit Selectron References Citations Bibliography Republished in IEEE Annals of the History of Computing, Volume 20 Number 4 (October 1988), pp. 11–28 External links The Selectron Early Devices display: Memories — has a picture of a 256-bit Selectron about halfway down the page More pictures History of the RCA Selectron Computer memory RCA brands Vacuum tubes