A History of Computer Graphics · All chapters.
Word sizes, memory, rates, dates and secondary sources for the machines after Sketchpad. Their photographs and cost boxes are in Section 3 of A History of Computer Graphics.
International Business Machines (IBM) announced the 2250 Display Unit in April 1964 as a peripheral of the System/360 (Weisberg). Its manual (IBM GA27-2701) describes 1,024 by 1,024 addressable positions over a 12 by 12 inch area; points, horizontal and vertical vectors and short 45-degree vectors in the basic unit, with an “Absolute Vectors” feature for any angle; 4 bytes of buffer per point or vector; an optional local buffer of 4,096 or 8,192 bytes from which the display refreshed itself; and a light pen with alphanumeric and programmed function keyboards. In 1972 Machover called the 2250 series “probably the most widely used graphic terminals over the past five years”.
The Digital Equipment Corporation (DEC), of Maynard, Massachusetts, delivered its first PDP-1 in 1960. The 1963 handbook gives an 18-bit word, 4,096 words of core at 5 µs (expandable to 65,536) and “100,000 additions per second.” Its Type 30 display was a 16-inch cathode-ray tube (CRT) plotting random points, 1,024 by 1,024 addressable over 9.25 by 9.25 inches (512 per axis distinguishable), at 20,000 points per second, with a Type 32 light pen. DEC built 53 PDP-1s, the last in 1969, and later wrote that some of the first had graphic displays, “the first commercially available graphic terminals for computers” (DEC, 1978; the company’s own claim).
On the PDP-1 at the Massachusetts Institute of Technology (MIT), Spacewar! was conceived in 1961 by Steve Russell, Martin Graetz and Wayne Wiitanen, written first by Russell and improved in spring 1962 by Samson, Edwards and Graetz; it sent “over 20,000 points per second to the Type 30 display” and spread to other PDP-1 sites through DEC’s user society (Computer History Museum, CHM).
M. R. Davis and T. O. Ellis at the RAND Corporation, under funding from the Advanced Research Projects Agency (ARPA), described the RAND Tablet in 1964 (RAND RM-4122-ARPA; American Federation of Information Processing Societies (AFIPS) Fall Joint Computer Conference 1964). It is reported to have had a 10 by 10 inch surface at 100 lines per inch. Machover (1972) notes that “the light pen could not be used with storage tube systems” (storage tubes), which pushed tablet development.
At the Stanford Research Institute (SRI), Douglas Engelbart’s Augmentation Research Center built NLS (the oN-Line System). His patent for an “X-Y position indicator for a display system,” two perpendicular wheels driving potentiometers, was filed on 21 June 1967 and granted on 17 November 1970 (US 3,541,541); this is the mouse. A museum label dates the first prototype to 1964 and credits Bill English with building it. NLS was shown to the Fall Joint Computer Conference in San Francisco on 9 December 1968 (Engelbart and English, “A research center for augmenting human intellect,” AFIPS 1968); the demonstration is reported to have lasted 90 minutes before about 1,000 people.
In a 1965 essay, “The Ultimate Display,” Sutherland described the display as “a looking glass into a mathematical wonderland” (Sutherland, 1965). Three years later he described one he had built. The work was “performed at Harvard University, supported in part by” ARPA, the Office of Naval Research (ONR) and Bell Telephone Laboratories (Bell Labs), after early work at Lincoln Laboratory (Sutherland, “A head-mounted three dimensional display,” AFIPS Fall Joint Computer Conference 1968). Philco’s Headsight of 1961 had already put a remote camera’s picture in front of the eyes (Carlson, sec. 17.1); Sutherland’s showed the computer’s own drawing.
The system was a pipeline of special-purpose units: a matrix multiplier, a clipping divider, an analog line generator, a headset with two miniature CRTs, mechanical and ultrasonic sensors for head position, and a general-purpose computer. It drew “3000 lines at 30 frames per second,” “a little over 10 microseconds per line.” The matrix multiplier transformed an endpoint in about 5 µs with 16 multiplications, “about 3,000,000 multiplications per second”; the clipping divider clipped a line in about 10 µs and did the perspective division. Each CRT’s picture was “about one half of an inch square,” seen as a virtual image about 18 inches away over a 40-degree field of view, overlaid on the room by half-silvered mirrors. The paper calls it a pipeline: “The matrix multiplier, clipping divider, and line-generator are connected in a ‘pipe-line’ arrangement.” The ceiling-mounted head sensor later gave the device its nickname, the Sword of Damocles, which the paper does not use.
The paper also names the next problem: “showing ‘opaque’ objects with hidden lines removed is beyond our present capability”; the only real-time solution it knew of was “a very expensive special-purpose computer at NASA Houston” (visibility).
Evans & Sutherland (E&S) turned the head-mounted display’s pipeline into a product. Its Line Drawing System-1 (LDS-1) is reported to have shipped first to Bolt Beranek and Newman in August 1969, with hardware 4 by 4 matrix transforms of homogeneous vertices driving a vector display, and to have gone to users including the National Aeronautics and Space Administration (NASA) Ames Research Center, the Port Authority of New York, MIT, Case Western Reserve and the Los Angeles Times (1970 reference manual, via a secondary source). A 1970 E&S advertisement in Datamation gives its speed: “10 microseconds typical for processing each line,” about 100,000 lines a second.