Tech POV


The First Non-Linear Edit System

In 1969 SMPTE released standard 12M – a specification for applying a universal time code to video. Assigning a unique number to every video frame was critical to the development of electronic editing as it enabled a list of all the edits in a program to be compiled. Thus was born the Edit Decision List or EDL. CBS and Memorex formed a company called CMX Systems to build editing systems using time code and EDLs. If you’ve never known a world where you couldn’t edit cat videos on your iPhone your reaction might be “meh.” But this was some radical engineering at the time.

In 1971 CMX released their first product: the CMX-600 light pen random access editor. Wildly ahead of its time, it stored monochrome video in analog format on Memorex computer drives and used a DEC PDP-11 mini-computer to control the system via a light pen interface. The system only held 30 minutes of low quality video, the disk drives took up a few hundred square feet of floor space and it cost the equivalent of three million bucks in 2015 dollars. But this revolutionary machine was the forerunner of all modern non-linear editing systems.

Of the first five systems CMX sold three went to CBS, one to CFI in LA and one to Teletronics in NYC. I had the privilege of sharing an office with the CMX-600 disk farm at my first full time job as an engineer at Teletronics. Typing this post on my Mac workstation, with its 82 Terabytes of attached storage, I can’t say I miss the big multi-disk Memorex platters each of which held only 5 minutes of video. But I do have a fondness for the CMX-600 and a great appreciation of the monumental effort it took to create it. And there’s much to be said for a heavily air conditioned machine room.

Thanks to Robert Lund for the pictures below. Lundo left Bell Labs to join Teletronics as one of the first digital engineers in post production. He maintained the CMX-600, wrote custom software for it and had the temerity to hire me in 1981 to design and build hardware for him.

The CMX-600
The CMX-600, as shown in the original CMX product brochure (1971)
Editing on a CMX-600
The real “Mad Men” edit a commercial at Teletronics using the CMX-600 (circa 1976)
Winkler Consulting Inc.