Early Graphics at Livermore

I think that Livermore’s first computer able to produce images was the IBM 704 computer which was equipped with the IBM 780 CRT display for direct viewing and the 740 film recorder with its own CRT. A program would put 10 bit x and y values in a word and execute an IO command that would cause that point to be plotted. The operation required 151 µsec. The CRT display had a slow phosphor and the point image would linger for a number of seconds on the display but the image was permanently captured on the film. By turning out the computer room lights substantial images could be seen on the display. The film recorder captured permanent images for better viewing however. A different IO command would cause the non-sprocketed film to advance one frame.

We requested a similar device for the LARC and it was delivered. We equipped the LARC with a sprocketed film magazine that was fast and precise. This allowed the production of black and white movies. An early production code on the LARC computed a general circulation weather model. Movies of the weather model caused other weather modelers to acquire such equipment. Perhaps the emergent jet stream was first noticed in the calculation via these movies.

A commercial machine called the “Houston Fearless” would take a strip of film and “color mix” it onto color film. Every third frame of the input strip would be exposed thru a filter of the same color. Each color frame would be exposed to three of the input frames each thru a different color filter, producing color movies.

By all obvious accounting methods color movies were the cheapest way to extract information from the computer for human consumption. They complemented and partly displaced traditional printer output.

Our first computer from Digital Equipment Corporation was the PDP-1. It was an 18 bit computer and each PDP-1 came with a CRT. The PDP-1 was programmed to do a variety of image tasks. The PDP-1 had a light pen which was used for a number of early graphical input ideas. Some were used in production. See this for a great deal more information of Livermore’s use of the PDP-1.

A few years later Livermore acquired a machine from Stromberg Carlson which used a characteron to produce an image on a Xerographic drum which was then transferred to paper.

The CalComp plotter arrived at Livermore in the late 50’s. This produced 30 inch by many inch drawings with a drum upon which the paper was wrapped, and a pen. Both the drum and pen were moved by a stepping motor that took individual step instructions from a mag tape. The plotter was fairly slow (300 steps/sec; 100 steps per inch) but it was reliable and good for short turn-around jobs. It was also low cost and high accuracy.