The RCA Selectron -- Preface

The preface at the end? Why not? The story of the Selectron is at its end. Just because we all showed up late....

This site describes the RCA Selectron, a Selective Electrostatic Storage Tube. The Selectron is a digital memory electron tube developed in the 1940s at the Princeton, New Jersey, Laboratories of the Radio Corporation of America for the then new discipline of electronic computing.

The origins of these pages began back in the 1960s when the author first began researching Cathode Ray Tubes. Looking inside the back of the television receiver offered little information, so it was off to the local library. Many books and journals showed the diversity of variations on the CRT -- a large bottle of mostly nothing. Eventually the text Storage Tubes by Knoll and Kazan was discovered. This treatment is hardly the How and Why Wonder Book of Cathode Ray Tubes. One of its numerous device descriptions was of a tube named the "Selectron." The Selectron was interesting in that it was digitally addressed and the author had just discovered the Fairchild 900-series of integrated circuits. The Selectron could store 256-bits, unlike the mostly analog images and patterns of most other storage tubes. And it was developed in the 1940s -- before general purpose digital computers existed. Indeed, the term "bit" had not yet entered the computer lexicon.

Over the years the Selectron would again hint at its presence: Researching Direct-View Storage Tubes as an engineer at Tektronix, Inc., studying digital addressing techniques for flat panel displays, visiting the David Sarnoff Library in Princeton, New Jersey and reading about the origins of digital computing and the RAND Corporation's 1950s computer, the JOHNNIAC. And one April evening in 2002 browsing the treasures available on eBay.

The item title was simply, "Giant Vacuum Tube 9.5" Tall 50 Prongs" but the small image was unmistakable: An RCA Selectron. Not the one shown in the books, but it was a Selectron. A bid was entered and eventually the auction was won. (Neither the maximum bid offered nor the final sale price will be disclosed to...er, protect the feelings and sensibilities of all parties involved.) Eventually a small package was received and it issued forth a Selectron. A prototype 1024-bit Selectron. In excellent condition. This was about as amazing as sending 45-cents in stamps to a post office box listed in an ad in the back of an issue of Popular Mechanics magazine and, four to six weeks later, receiving a Faberge Egg!

Contacting the seller for any provenance of this artifact yielded a mixed bag. He could offer nothing other than it came from an estate sale in Maryland during the previous year. He got to the sale an hour and a half early and was looking around and found it "in the trash to be hauled to the dump." Asking about it the lady running the sale told him to just put it in his van before the sale started. (The mind reels at what other unique and historic material went to the dump that day....) But he had picked up another tube at that sale which was similar in appearance! An offer was made, the deal was closed and a 4096-bit Selectron prototype soon joined its sibling.

With privilege comes responsibility, and that is the origin of this site. Of the two hundred Selectrons built by RCA only twelve have been positively located, and only two of those are available for public viewing. No books were ever written about the Selectron nor its developers and users. A handful of blurbs and a twenty page piece in the RCA Review are the written legacy of this short-lived but remarkable electron tube. This site is an attempt to bring the Selectron and its developers and users back into the light.





Earlier pages were hand coded using Notepad. Later pages hand coded using Atom.
Images were enhanced and/or produced using Adobe Photoshop version 5.
The index page image is based upon Vassos' endpaper artwork for the RCA Library holdings.
Animated simulations were produced with MIT's Processing release 0066.
Many patents were obtained with Patent Logistics, Inc., Patent Fetcher website and Google Patents.
Documents were OCR'd with ABBYY Reader version 5 and PDF'd with Adobe Acrobat version 4 and at SmallPDF.com
(Slothful verbification is humbly apologised for.)
The main index script was built with Sothink DHTMLMenu version 5.1
Much research was performed and some images derived from Americanradiohistory
My brain is release 1.0x (no further releases anticipated)

Thank you for visiting, and all information, comments and suggestions are welcome, appreciated and will be acknowledged.

Charles S. Osborne
Portland, Oregon, USA
September 2003



The author is an electrical engineer, receiving his degree in 1975 from the California Polytechnic State University (CalPoly) at San Luis Obispo, California, and had been a member of the Society for Information Display since 1972. E-mail links are at the bottom of most pages on this site.


(Oh, and since you were so kind and thorough to read this preface, please return to the main page -- the menu with the artwork of John Vassos -- and roll your mouse cursor over the Selectron pins on the bottom of the image of the device. This is a small homage to "cellular automata" an interest of John von Neumann, and to John Horton Conway the author of "The Game Of Life" ...and to you for stopping by.)

oz