Adobe’s PostScript programming language sparked a revolution. Now you can check out the source code

The Computer History Museum (CHM) has, with Adobe’s permission, released the source code for an early version of PostScript, a programming language developed in the early 1980s by Adobe, which helped usher in desktop publishing and spawned the Portable Document Format (PDF).

“PostScript and the Adobe Type Library revolutionized printing and publishing, and kickstarted the explosive growth of desktop publishing starting in the 1980s,” the CHM said.

Adobe shipped the first release of PostScript in 1984, two years after the company was founded, and Apple co-founder Steve Jobs approached the firm to make PostScript useful for emerging laser printers, which were first developed at Xerox Palo Alto Research Center (PARC). 

Apple launched its nearly-$7,000 LaserWriter printer unit with built-in PostScript in 1985, helping spark the desktop printing boom. 

As noted by David C. Brock, CHM’s director of Curatorial Affairs, and director of its Software History Center, Adobe co-founders Chuck Geschke and John Warnock — PostScript’s architect — started discussions with Digital Equipment Corporation and Apple about using software for 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,” writes Brock. 

“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,” he adds later. 

The other advance from Adobe was professional-quality typefaces for use within PostScript. Adobe’s PDF file format, which was standardized in 2008, is also based on PostScript and has today replaced PostScript as the format for cross-platform document sharing.  

Prior to founding Adobe, Geschke, Warnock and others had worked together at Xerox PARC where they developed Interpress, which Xerox decided would be its printing standard. But due to delays in making that happen, Geschke and Warnock opted to leave and started Adobe to create their rival to Interpress. The pair also attracted other key talent from PARC to join Adobe and work on PostScript.  

As Brock notes, Adobe approached typefaces and fonts differently to PARC. But the growing team at Adobe still hadn’t figured out how to give PostScript “device-independence”.  

Warnock and his colleagues apparently solved the problem with a set of procedures for the rendering of text that remained a secret in PostScript’s source code until he publicly disclosed their existence in 2010.  

Geschke notes in an interview with CHM that PostScript was developed in the days before software was patentable. 

“We wouldn’t have even filed a patent anyway, because to file a patent, you have to disclose and we didn’t want to disclose because it was really some of the magic of our implementation of PostScript,” he explains. 

Acorn to Brick, the PostScript source code CHM has released is a version of PostScript from 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,” explains Brock.