Capacitance Electronic Disc

The Capacitance Electronic Disc (CED) is an analog video disc playback system developed by RCA, in which video and audio could be played back on a TV set using a special needle and high-density groove system similar to phonograph records.

Capacitance Electronic Discs
A CED of Close Encounters of the Third Kind, exposed from its protective caddy
Media typevideo playback media
Capacity60 minutes NTSC video per side, 27,000 still frames per side[1]
Read mechanismStylus
UsageHome video

First conceived in 1964, the CED system was widely seen as a technological success which was able to increase the density of a long-playing record by two orders of magnitude.[2] Despite this achievement, the CED system fell victim to poor planning, conflicts within RCA, and technical difficulties that slowed development and stalled production of the system for 17 years—until 1981, by which time it had already been made obsolete by laser videodisc (DiscoVision, later called LaserVision and LaserDisc) as well as Betamax and VHS video cassette formats. Sales for the system were nowhere near projected estimates. In the spring of 1984, RCA announced it was discontinuing player production, but continuing the production of videodiscs until 1986, losing an estimated $600 million in the process. RCA had initially intended to release the SKT425 CED player with their high end Dimensia system in late 1984, but cancelled CED player production prior to the Dimensia system's release.[3]

The format was commonly known as "videodisc", leading to much confusion with the contemporaneous LaserDisc format. LaserDiscs are read optically with a laser beam, whereas CED discs are read physically with a stylus (similar to a conventional gramophone record). The two systems are mutually incompatible.

RCA used the brand "SelectaVision" for the CED system, a name also used for some early RCA brand VCRs,[4] and other experimental projects at RCA.[5][6]


Beginnings and release

RCA began videodisc research in 1964, in an attempt to produce a phonograph-like method of reproducing video. Research and development was slow in the early years, as the development team originally comprised only four men,[7] but by 1972, the CED team at RCA had produced a disc capable of holding ten minutes of color video (a portion of the Get Smart episode "A Tale of Two Tails", re-titled "Lum Fong").[8]

The first CED prototype discs were multi-layered, consisting of a vinyl substrate, nickel conductive layer, glow-discharge insulating layer and silicone lubricant top layer. However, failure to fully solve the stylus and disc wear and complexity of manufacturing forced RCA to search for simpler solutions to the problem for constructing the disc. The final disc was crafted using PVC blended with carbon to allow the disc to be conductive. To preserve stylus and groove life, a thin layer of silicone was applied to the disc as a lubricant.

CED videodiscs were originally meant to be sold in jackets and handled by hand similar to audio records, but during testing, it was shown that exposure to dust caused skipped grooves. It was learned that if dust was allowed to settle on the discs, then the dust would absorb moisture from the air and cement the dust particle to the disc surface, causing the stylus to jump back in a locked groove situation. Thus, an idea was developed in which the disc would be stored and handled in a caddy from which the CED would be extracted by the player so that exposure to dust would be minimized.[9]

After 17 years of research and development, the first CED player (model SFT100W) was released on March 22, 1981. A catalog of approximately 50 titles was released at the same time.[10] The first title to be manufactured was Race for Your Life, Charlie Brown.[10] Fifteen months later, RCA released the SGT200 and SGT250 players, both with stereo sound while the SGT-250 was also the first CED player model to include a wireless remote control. Models with random access hit the market in 1983.


Several problems doomed the new CED system before it was even introduced. From an early point in the development of the CED system, it was clear that VCRs and home videotape—with their longer storage capacity and recording capabilities—would pose a threat to the system.[11] However, development pushed ahead. Once finally released, sales for the new CED players were slow; RCA had expected to sell 200,000 players by the beginning of 1982, but only about half that number had been sold, and there was little improvement in sales throughout 1982 and 1983.[2][12]

"...Machiavelli noted that '..there is nothing more difficult to take in hand, more perilous to conduct, or more uncertain in its success, than to take the lead in the introduction of a new order of things...' At videodisc, I believe these words had special significance..."
Dr. Jay J. Brandinger, Vice President, RCA SelectaVision Videodisc Operations, June 27, 1986.[13]

The extremely long period of development—caused in part by political turmoil and a great deal of turnover in the high management of RCA—also contributed to the demise of the CED system. RCA had originally slated the videodisc system for a 1977 release. However, the discs were still not able to hold more than thirty minutes of video per side, and the nickel-like material used to make discs was not sturdy enough to put into manufacturing. Signal degradation was also an issue, as the handling of the discs was causing them to deteriorate more rapidly than expected, baffling engineers.

RCA had hoped that by 1985 CED players would be in close to 50% of American homes,[2] but the sales of players continued to drop. RCA attempted to cut the prices of CED players and offer special incentives to consumers such as rebates and free discs, but sales only slightly improved. RCA management realized that the system would never be profitable and announced the discontinuation of production of CED players on April 4, 1984.[12] In an unexpected twist, demand for the videodiscs themselves became high immediately after the announcement, so RCA alerted customers that videodiscs would continue to be produced and new titles released for at least another three years after the discontinuation of players. Shortly after this announcement, however, the sale of discs declined sharply, prompting RCA to abandon disc production after only two years, in 1986.[14] The last titles released were The Jewel of the Nile by CBS/Fox Video,[15] and Memories of VideoDisc, a commemorative CED given to many RCA employees involved with the CED project,[16] both in 1986.


CED players, from an early point in their life, appealed to a lower-income market more than VHS, Betamax, and LaserDisc. The video quality (approximately 3 MHz of luma bandwidth for CED[1]) was comparable to a VHS-SP or Betamax-II video, but sub-par compared to LaserDisc (about 5 MHz of luma bandwidth).

CED players were intended to be "low-cost". Because they have fewer precision parts than a VCR, a CED player cost, at most, about half as much to manufacture.[17] The discs themselves could be inexpensively duplicated, stamped out on slightly-modified audio gramophone record presses.

Like VCRs, CED videodisc players had features like rapid forward/reverse and visual search forward/reverse. They also had a pause feature, though it blanked the screen rather than displaying a still image; many players featured a "page mode", during which the current block of four successive frames would be repeatedly displayed.

Since CEDs were a disc-based system, they did not require rewinding. Early discs were generally monaural, but later discs included stereo sound. (Monaural CED discs were packaged in white protective caddies, while stereo discs were packaged in blue protective caddies.) Other discs could be switched between two separate mono audio tracks, providing features such as bilingual audio capability.

Like the LaserDisc and DVD, some CEDs feature random access, allowing users to quickly move to certain parts of the movie. Each side of a CED disc could be split into up to 63 "chapters", or bands. Two late RCA players (the SJT400 and SKT400) could access these bands in any given order. Unlike its laser-based counterparts, the chapters in a CED are based on minutes of the film, not scenes.

Novelty discs and CED-based games were produced whereby accessing the chapters in a specified order would string together a different story each time. However, only a few were produced before the halt of CED player manufacturing.[18]


In comparison with LaserDisc technology, CEDs suffered from the fact that they were a phonograph-related contact medium: RCA estimated that the number of times a CED could be played back, under ideal conditions, was 500.[19] By comparison, a clean, laser rot-free LaserDisc could, in theory, be played an unlimited number of times (although repeated handling could still result in damage).

Since the CED system used a stylus to read the discs, it was necessary to regularly change the stylus in the player to avoid damage to the videodiscs, while worn and damaged discs also caused problems for consumers. When a disc began to wear, video and audio quality would severely decline, and the disc would begin to skip.[19] Several discs suffered from a condition called "video virus", where a CED would skip a great deal due to dust particles stuck in the grooves of the disc. However, playing the disc several times would generally solve this problem.[20]

Unlike VHS tapes, CEDs required a disc flip at some point during the course of almost all films as only sixty minutes of video could be stored per side (75 mins on UK PAL discs due to the slower rotation speed); if a feature ran over two hours, it would be necessary to spread the feature over two discs.

In some cases, if a movie's theatrical running time was only slightly longer than two hours, studios would often trim short scenes throughout the movie and/or employ time compression (speeding the extra run time out of the film) in order to avoid the expense of issuing two discs.

This problem was not unique to CEDs: LaserDiscs presented the same difficulty, and some longer features, such as The Ten Commandments (1956), still required more than one tape or disc in the VHS, Beta, and LaserDisc formats. There were no two-disc UK PAL releases.

Less significant disadvantages include lack of support for freeze-frame during pause, since CEDs scanned four frames in one rotation versus one frame per rotation on CAV LaserDisc, while computer technology was not advanced enough at the time to outfit the player with a framebuffer affordably. However, a "page mode" was available on many players that would allow those four frames to be repeated in an endless loop.[21]

CEDs were also larger than VHS tapes, thicker than LaserDiscs, and considerably heavier due to the plastic caddies.

Available material


CED players were manufactured by four companies—RCA, Hitachi, Sanyo, and Toshiba—but seven other companies marketed players manufactured by these companies.[22][23]


Upon release, 50 titles were available for the CED; along with RCA (which included the company's partnership with Columbia Pictures plus Paramount and Disney releases), CBS Video Enterprises (later CBS/FOX Video) produced the first 50 titles.[13] Eventually, Disney, Metro-Goldwyn-Mayer, Paramount Pictures, MCA, Vestron Video, and other labels began to produce CED discs under their own home video labels, and did so until the end of disc manufacturing in 1986.

See also


  1. "RCA SelectaVision VideoDisc FAQ - What are the technical specifications of the RCA VideoDisc system?". Retrieved 2007-03-07.
  2. "RCA SelectaVision VideoDisc FAQ - Why did the CED system fail to even come close to RCA's expected market penetration?". Retrieved 2007-03-11.
  3. Howe, Tom. "RCA Dimensia SKT425 CED Video Disc Player".
  4. "VBT200 - The First RCA SelectaVision VHS Video Cassette Recorder (VCR)". Retrieved 2007-03-14.
  5. "HoloTape". Retrieved 2007-03-06.
  6. "MagTape". Retrieved 2007-03-06.
  7. "First Successful RCA SelectaVision VideoDisc Produced in 1972". Retrieved 2007-03-14.
  8. "Lum Fong - First Successful RCA VideoDisc Web Page". Retrieved 2007-03-06.
  9. "Comparison of 1977 CED Media to Final Production Media". Retrieved 2007-03-10.
  10. "Race For Your Life, Charlie Brown - The First RCA VideoDisc Title". Retrieved 2007-03-10.
  11. "Richard Sonnenfeldt's "VIDEODISK" Book Chapter". Retrieved 2007-03-11.
  12. "RCA SelectaVision VideoDisc FAQ - Why did RCA abandon further development of the CED system in April 1984?". Retrieved 2007-03-11.
  13. Jay J. Brandinger (June 27, 1986). Memories of VideoDisc (Capacitance Electronic Disc). Rockville Road, Indiana: RCA, Inc.
  14. "Memories of VideoDisc - CED Retailing at G&M Video in Indiana". Retrieved 2007-03-11.
  15. "Memories of VideoDisc - Milestones - The Last Production CED Title". Retrieved 2007-03-14.
  16. "Memories of RCA VideoDisc Main Page". Retrieved 2007-03-14.
  17. "The early days" by J. K. Clemens and E. O. Keizer. "Electronic Servicing & Technology" magazine 1982 May.
  18. "A Walk Through the Universe CED Web Page". Retrieved 2007-03-12.
  19. "RCA SelectaVision VideoDisc FAQ - How long can I expect my CED VideoDiscs to last?". Retrieved 2007-03-14.
  20. "RCA SelectaVision VideoDisc FAQ - Why do some of my CED's skip, and what can I do to correct this?". Retrieved 2007-03-14.
  21. "CED Player Specifications". Retrieved 2008-03-14.
  22. "RCA SelectaVision VideoDisc FAQ - Who manufactured CED Players, and how many different models are there?". Retrieved 2007-03-18.
  23. "CED Player Name Brand Links". Retrieved 2007-03-18.

Further reading

  • Cowie, Jefferson R. Capital Moves: RCA's Seventy-Year Quest for Cheap Labor. Ithaca, N.Y.: Cornell University Press, 1999. ISBN 0-8014-3525-0.
  • Daynes, Rob and Beverly Butler. The VideoDisc Book: A Guide and Directory. New York: John Wiley and Sons, 1984. ISBN 0-471-80342-1.
  • DeBloois, Michael L., ed. VideoDisc/Microcomputer Courseware Design. Englewood Cliffs, N.J.: Educational Technology Publications, 1982. ISBN 0-87778-183-4.
  • Floyd, Steve, and Beth Floyd, eds. The Handbook of Interactive Video. White Plains, NY: Knowledge Industry Publications. 1982. ISBN 0-86729-019-6.
  • Graham, Margaret B.W. RCA and the VideoDisc: The Business of Research. (Also as: The Business of Research: RCA and the VideoDisc.) Cambridge: Cambridge University Press, 1986. ISBN 0-521-32282-0, ISBN 0-521-36821-9.
  • Haynes, George R. Opening Minds: The Evolution of Videodiscs & Interactive Learning. Dubuque, Iowa: Kendall/Hunt Publishing Co., 1989. ISBN 0-8403-5191-7.
  • Howe, Tom. CED Magic: The RCA VideoDisc Collector's Guide. Portland, OR: CED Magic, 1999. ISBN 0-9670013-0-7. (CD-ROM)
  • Isailovi´c, Jordan. VideoDisc and Optical Memory Systems. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-942053-3.
  • Lardner, James. Fast Forward: Hollywood, the Japanese, and the VCR Wars. (Also as: Fast Forward: Hollywood, the Japanese, and the Onslaught of the VCR.) New York: W. W. Norton & Co Inc., 1987. ISBN 0-393-02389-3.
  • Lenk, John D. Complete Guide to Laser/VideoDisc Player Troubleshooting and Repair. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-160813-4.
  • Schneider, Edward W., and Junius L. Brennion. The Instructional Media Library: VideoDiscs, (Volume 16). Englewood Cliffs, NJ: Educational Technology Publications. ISBN 0-87778-176-1. 1981.
  • Sigel, Efrem, Mark Schubin and Paul F. Merrill. Video Discs: The Technology, the Applications and the Future. White Plains, N.Y. : Knowledge Industry Publications, 1980. ISBN 0-914236-56-3. ISBN 0-442-27784-9.
  • Sobel, Robert. RCA. New York: Stein and Day/Publishers, 1986. ISBN 0-8128-3084-9.
  • Sonnenfeldt, Richard. Mehr als ein Leben (More than One Life). ?, 2003. ISBN 3-502-18680-4. (In German.)
  • Journals:
    • The Videodisc Monitor
    • Videodisc News
    • Videodisc/Optical Disk Magazine
    • Video Computing
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