The story of PostScript has many different facets. It is a story about profound changes in human literacy as well as a story of trade secrets within source code. It is a story about the importance of teams and of geometry. And it is a story of the motivations and educations of engineer-entrepreneurs.
The Computer History Museum is excited to publicly release, for the first time, the source code for the breakthrough printing technology, PostScript. (Register to download the code here.) We thank Adobe for the company’s permission and support, and Adobe cofounder John Warnock for championing this release.
The Big Picture of Printing
Printing has always been a technology with profound cultural consequences. Movable type first emerged in East Asia. Later, in 15th-century Europe, the printing press evolved from technology from wine and oil presses combined with novel practices to mass-produce type using metal casting. With the printing press came a revolution in human literacy. Books became cheaper and quicker to produce, and as a result appeared in ever greater numbers. Literacy and libraries expanded. Greater access to information transformed learning, research, government, commerce, and the arts.
John Warnock [left] and Chuck Geschke founded Adobe Systems in December 1982.Adobe and Doug Menuez
From the start of Adobe Systems (now Adobe) 40 years ago, in December 1982, the firm’s cofounders envisioned a new kind of printing press—one that was fundamentally digital, using the latest advances in computing. Initial discussions by cofounders Chuck Geschke and John Warnock with computer makers such as Digital Equipment Corp. and Apple convinced them that software was the key to the new digital printing press. Their vision: Any computer could connect with printers and typesetters via a common language to print words and images at the highest fidelity. Led by Warnock, Adobe assembled a team of skillful and creative programmers to create this new language. In addition to the two cofounders, the team included Doug Brotz, Bill Paxton, and Ed Taft. The language they created was a complete programming language, named PostScript, and was released by Adobe in 1984.
In this video, Geschke discusses how Adobe came to focus on PostScript:
Chuck Geschke discusses how Adobe came to focus on PostScript as their initial businessComputer History Museum
By treating everything to be printed the same, in a common mathematical description, PostScript granted abilities offered nowhere else. Text and images could be scaled, rotated, and moved at will, as in the opening image to this essay. Adobe licensed PostScript to computer and printer manufacturers, and the business jumped into a period of hypergrowth. There was tremendous demand for the new software printing press. Computer makers from the established worlds of minicomputers and workstations to the rapidly growing world of personal computers adopted the technology. Printer makers joined in, from those selling well-established printers to the new laser printers and professional typesetters. Software makers rushed to make their offerings compatible with PostScript.
Fueling this growth were advances Adobe was making around a critical need: providing professional-quality digital typefaces—and the many fonts that comprise them—for use within PostScript. Adobe developed a fresh approach to describing typefaces geometrically, and the company licensed many of the most well-known typefaces, including those for Asian languages. PostScript and the Adobe Type Library revolutionized printing and publishing, and kickstarted the explosive growth of desktop publishing starting in the 1980s. PostScript became so successful that it grew into a de facto standard internationally, with Adobe publishing the details of the PostScript language and allowing others to create products that were PostScript-compatible. Today, most printers rely on PostScript technology either directly or through a technology that grew out of it: PDF, or Portable Document Format.
Trajan was an early typeface created by Adobe using its new technologies.Adobe
Warnock championed the development of PDF in the 1990s, transforming PostScript into a technology that was safer and easier to use for digital documents, but retaining all the benefits of interoperability, fidelity, and quality. Over the decades, Adobe continued to enhance PDF’s features, making it a crucial standard for creating digital documents, printing them, and displaying graphics of all kinds on screens from desktops to laptops to smartphones and smartwatches.
Today, the digital printing press has far exceeded anything envisioned by the Adobe cofounders when they first set out to create PostScript with their team. Almost everything printed on paper is done so using computers. Indeed, in many areas of the world, computers have become the overwhelming tool for writing. As Doug Brotz puts it, PostScript “democratized the print world.” With PDF now so successful that it too has become a global standard, the number of PDFs created each year measures in the trillions.
PostScript’s Graphical Roots
Typography is the combination of art and technique that is concerned with the display of writing, especially as printed. It is concerned with the shape and placement of characters, words, paragraphs, and so on. In this, typography is thoroughly graphical, a matter of visual design. Digital typography is no different, just focused to computer techniques and displays. It is fitting, then, that the roots of PostScript and its contributions to the development of digital typography lie in advanced computer graphics.
Warnock, the architect for PostScript, launched his computing career as a graduate student at the University of Utah at the close of the 1960s. Utah was then one of the world’s foremost centers for advanced computer graphics research. In his work there and then at a computer graphics firm run by Utah’s lead professors, David Evans and Ivan Sutherland, Warnock embraced their characteristic geometric approach to computer graphics. Shapes, scenes, images, and animations were created and designed using mathematics to describe the geometry of the visual and using various computer procedures to realize these descriptions as imagery. In particular, Warnock was impressed with the power of a procedural computer language, called the Design System, that he and John Gaffney helped to develop at Evans and Sutherland’s firm.
In 1978, Chuck Geschke had just set up the Imaging Science Laboratory within the famed Xerox Palo Alto Research Center (PARC). Geschke hired Warnock to take up a pressing challenge for the lab. PARC was creating a set of experimental computers that had new kinds of displays and that were intended to be used with an array of novel printers—as PARC had recently invented the laser printer. Warnock’s challenge was to create a device-independent graphics system that could be used across any computer, display, or printer.
Warnock saw that something like the Design System could work in this new computing environment, but refocused from 3D graphics to PARC’s concern with professional-quality printing and high-quality display of text and images. The result was another geometrical, procedural language called JaM, which Warnock created in partnership with PARC researcher Martin Newell. (The illustration at top was created using JaM.)
From 1979 into 1981, JaM became a major component in a new effort in Geschke’s laboratory. This was a push to develop a commercial printing language that could be used with the production version of PARC’s experimental computers called the Xerox Star, and more broadly used across all of Xerox’s lines of printers. A group of six researchers—Geschke, Butler Lampson, Jerry Mendelson, Brian Reid, Bob Sproull, and Warnock—melded the JaM approach with other, more established protocol techniques. The result was named Interpress.
Xerox leadership was quickly convinced of the potential for Interpress, deciding that it would indeed be developed into the firm’s printing standard. However, moving to this standard would take several years, during which time Interpress would be under wraps. This delay spurred Geschke and Warnock to move. They would leave PARC and found a startup in which they would create a rival to Interpress, but built more fully along the geometric, procedural language approach that Warnock found to be so powerful. For the new startup to create this new language, PostScript, as the digital printing press, it would require a brilliant team.
In this video clip, Geschke discusses the motivations behind the formation of Adobe:
Chuck Geschke discusses the motivations behind the formation of AdobeComputer History Museum
In this video clip, Warnock discusses key early actions in establishing Adobe.
John Warnock discusses key early actions in establishing AdobeComputer History Museum
The Team that Created PostScript
In December 1982, when Geschke and Warnock founded Adobe Systems, the new printing language they intended to create was at the very center of their plans, hopes, and vision. The future of the firm hinged on PostScript. Geschke and Warnock were themselves both highly experienced software creators. Geschke had earned his Ph.D. at Carnegie Mellon University working on advanced compilers and had been a leader in the creation of an important programming language developed and used at PARC called Mesa. As discussed, Warnock had a Ph.D. in computer graphics software from the University of Utah and years of experience creating languages exactly like their envisioned PostScript. But perhaps because of their extensive background in creating cutting-edge software, the cofounders knew they needed to expand their team to create PostScript.
Early Adobe employees and friends sail in the San Francisco Bay on a company outing.Adobe
Adobe’s PostScript team quickly took shape as three other highly talented software creators from PARC decided to join with Geschke and Warnock: Doug Brotz, Bill Paxton, and Ed Taft. Brotz had earned a Ph.D. in computer science from Stanford before joining PARC in 1977. Paxton also had a Ph.D. in computer science from Stanford and joined PARC the same year as Brotz. Taft had joined PARC earlier, hired by Geschke right after finishing his undergraduate studies at Harvard in 1973. Together, and with input from Adobe colleagues like Andy Shore, the team created PostScript by the close of 1984.
A Trade Secret in the Source Code
Adobe’s commitment to a geometrical approach for PostScript carried consequences for how it would contend with typefaces—distinctive character shapes—and the numerous fonts that actually realize these typefaces at different sizes and styles (point sizes, regular, italic, bold, and so on). At PARC, fonts had been created as a set of individual hand-crafted bitmap images, with static definitions of which bits were on and which were off for each character of the font. Meanwhile, though, researchers at PARC and beyond were exploring ways to define character shapes mathematically. At Adobe, the team followed this mathematical description approach to fonts, in keeping with the broader direction of PostScript, defining characters using Bézier curves.
But this still left the problem of device-independence. How could Adobe’s font definitions contend with different displays, printers, and different resolutions on both? For eyes accustomed to reading published text, even the slightest inconsistencies or irregularities in the appearance of text are readily noticed and jarring. At lower resolutions, the chance for these defects only becomes worse. Rendering fonts reliably at different resolutions was a critical issue. Without a solution, PostScript could never become the digital printing press.
Elements of Adobe’s secret solution to creating professional-quality fonts for different resolutions on displays and printers.John Warnock
It was Warnock who came up with Adobe’s solution, turning the problem itself into the solution. The resolution of the output would determine a set of procedures that would correct the fonts to optimize their appearance at that resolution. Warnock, Brotz, and Paxton worked on the procedures for months, eventually settling on ways to define key aspects of the font shapes and fitting them to the pixel rows and columns of the specified resolution, changing some aspects of the character shapes depending on the resolution. Eventually, the Adobe team decided that greatest advantage lay in keeping these approaches and procedures as a trade secret. They stayed secret in PostScript’s source code, known to very few at the company, until Warnock publicly disclosed them in a 2010 lecture. In this video clip, Geschke discusses the trade secret in the PostScript source code:
Chuck Geschke discusses the trade secret in the PostScript source codeComputer History Museum
The version of the PostScript source code released to the public by the Computer History Museum is a very early version, dating to late February 1984. While this version does contain an early version of the “font hinting” procedures later kept as a trade secret, these approaches were completely rewritten, expanded, and refined by Bill Paxton in subsequent months. These changes were critical to the success of PostScript as it fully came to market.
Editor’s note: This post originally appeared on the blog of the Computer History Museum.
Acknowledgements: Thank you to Doug Brotz and Bill Paxton for their helpful comments on a draft of this essay. Thank you to Adobe and Doug Menuez for permission to use several images.
This essay is based on oral histories and interviews conducted by the Computer History Museum as well as several critical published sources:
John E. Warnock, “The Origins of PostScript,” in IEEE Annals of the History of Computing, vol. 40, no. 3, pp. 68-76, Jul.-Sep. 2018, doi: 10.1109/MAHC.2018.033841112.
John E. Warnock, “Simple Ideas That Changed Printing and Publishing,” in Proceedings of the American Philosophical Society, vol. 156, no. 4, 2012, pp. 363–78. JSTOR, http://www.jstor.org/stable/23558230.
John E. Warnock and Charles Geschke, “Founding and Growing Adobe Systems, Inc.,” in IEEE Annals of the History of Computing, vol. 41, no. 3, pp. 24-34, July-Sept. 2019, doi: 10.1109/MAHC.2019.2923397.
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David C. Brock is an historian of technology, director of curatorial affairs at the Computer History Museum, and director of CHM’s Software History Center. He focuses on histories of computing and semiconductors as well as on oral history. He is the coauthor of Moore’s Law: The Life of Gordon Moore, Silicon Valley’s Quiet Revolutionary and is on Twitter @email@example.com.