I missed this fascinating 2022 post on the history of PostScript (and, by extension, the PDF)—by David Brock for the Computer History Museum:
From the start of Adobe Systems Incorporated (now Adobe, Inc.) exactly forty 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 Corporation 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 in fact a complete programming language, named PostScript, and was released by Adobe in 1984.
The source code from 1984 is included.