He could only find one such case, which he reasonably decided to ignore: Although Hershey only implemented a subset of Japanese characters as a demonstration, he searched through over 5000 of them looking for glyphs which might exceed the limitations of his method. An example of his thoroughness is found in his 1967 report “Calligraphy for Computers”. In addition to mathematical symbols, he showed how the plotter could draw electronic circuit diagrams, stellar maps of the galaxy, maps in general, chemical bonds, etc. In his reports he demonstrated fonts not only in English, but in other languages such as Greek, Russian, and Japanese. In hindsight, he not only built a set of tools to solve the needs of the Dahlgren community, but pushed the limits of the optical plotter to the extreme. Works for All Languages (Except Dragons in Motion) He focused on using vectors to design his fonts, and embarked on the lengthy journey of researching and building his collection of vector-based fonts. Dr Hershey realized he could expand this to embrace more exotic and artistic glyphs. Furthermore, it opens up the ability to plot data directly onto film, bypassing the slower pen-plotter and even slower hand-drawing techniques of the day.ĭr Hershey learned that engineers at the Bell Laboratories in Murray Hill, New Jersey had developed a font for their optical printer using a similar technique, approaching it from a rasterization point of view. When applied to text, this is of course slower than using the stencil, but it allows an arbitrary selection of fonts, or repertories as Dr Hershey called them. Rather, the film would be exposed by using the period (full stop) stencil as a “dot”, and moving the dot under program control. The key to make this happen was to define a new mode of output which bypassed the internal stencil fonts. Dr Hershey not only saw this possibility, but possessed a keen interest in calligraphy and didn’t mind spending his evenings developing this new capability. Hershey came to the realization that the NORC’s optical printer could take on a new role and be used as a typesetter. Plots and figures would generally be hand-drawn or by pen plotter. But special-purpose typewriters like the Varityper were needed to typeset math equations. The text itself would be prepared using an ordinary typewriter. Inspirationīack in those days, before roff, LaTex, and WYSIWYG word processors, preparing technical reports full of complicated mathematical equations and data plots was quite time consuming. But soon the system would be utilized in ways not imagined by the original designers. No raster scanning or vector drawing was involved, so the process was fast. The electron beam projects an entire letter on the phosphor face of the tube in one “flash”, which in turn exposes photographic film. This special CRT has an internal metal screen into which a font is etched. What made this device so fast? It was the Charactron Tube which we covered back in 2017. Charactron Tube Diagram (US Patent 2735956) While this printing speed was certainly impressive, the ability to plot entire graphs and figures in just fractions of a second was no doubt well appreciated by the scientists at Dahlgren. But despite this wait time, the printing speed was much faster than line printers of the day: 7000 lines per minute vs 150. Since they used film, they required chemical processing to become photos, slides, or microfilm. Perhaps you’ve heard stories of programmers waiting impatiently for printouts from mainframe operators? Well you would have waited even longer for your optical plots. SC4020 Computer Recorder Information Manual
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