In the late 1970s, the world of printing was dominated by a myriad of proprietary languages, each tailored to the idiosyncrasies of individual printers and typesetters. This fragmented landscape meant that word processors from distinct companies could only communicate effectively with printers from the same manufacturer. It was during this chaotic period that a group of innovative engineers at Xerox PARC recognized the pressing need for a unified solution to streamline the printing process.

Their breakthrough was a language called Interpress, designed specifically for controlling Xerox laser printers. For context, in 1980, the cost of a laser printer ranged from an astonishing $10,000 to $100,000, making it a significant investment for any organization. Despite their best efforts, John Warnock and his supervisor, Chuck Geschke, faced difficulties in commercializing Interpress for two years, ultimately leading them to pivot.

In an ambitious move, they founded Adobe, a name that has since become synonymous with digital creativity. Originally, the company's vision hinged on producing laser printers, but they soon recognized a more lucrative opportunity: licensing their technology to other manufacturers. This pivot was the genesis of PostScript, a revolutionary language that would forever change the landscape of printing and publishing.

The early iteration of PostScript bore similarities to the computing language Forth, featuring a set of commands tailored for page layout and laser printing. Its success was attributed to several key advantages. First, the specifications were readily accessible for developers looking to write printer drivers, which encouraged widespread adoption. Notably, Apple chose PostScript for its LaserWriter printer, which boasted a more powerful computer than many of the Macs it was connected to, retailing at about $7,000.

Secondly, printer manufacturers could easily license PostScript for their devices, eliminating the need for costly in-house development of proprietary languages. This accessibility significantly enhanced competition and innovation within the printing sector. Finally, PostScript introduced device independence: a PostScript file printed on a 300 DPI laser printer would yield quality output, while the same document printed on a high-resolution 2400 DPI typesetter would produce even finer results. This capability was a game-changer during a time when file sizes were a major concern for users.

The combination of a Mac computer and a LaserWriter wasnt complete without the right software. Because the PostScript specification was open, software development flourished. Aldus Corporation released PageMaker, which is credited with pioneering the desktop publishing industry. Additionally, the printing giant Linotype introduced a typesetting machine compatible with PostScript, streamlining the journey from digital design to physical print.

For those unfamiliar with this era, its important to understand the profound impact of the desktop publishing revolution. Before its advent, the quality of computer-generated output left much to be desired. To produce a camera-ready document, skilled labor was required to create a print-ready layout, something that can now be achieved with a few clicks in any modern word processor.

As technology progressed, Adobe sought to innovate further. In the late 1980s, they introduced Display PostScript, designed to enhance screen rendering. The NeXT computer was one of the first systems to adopt this technology. While it was a clever solution, it didn't perform optimally on the hardware available at the time, and Adobe's licensing fees deterred potential adopters in a market that was becoming increasingly competitive.

The year 1991 marked a significant milestone with the release of PostScript Level 2, effectively retroactively branding the original PostScript as Level 1. This updated version included improvements such as enhanced speed and stability, better color separation, and improved handling of compressed images. However, an early release of the specifications led to competition that allowed rivals to introduce features for Level 2 ahead of Adobe, complicating their market position.

Ultimately, Adobe launched PostScript 3 and dropped the Level designation. This version introduced support for 12-bit color, enhancing the fidelity of color reproductions and, importantly, added support for PDF files.

The distinction between PostScript and PDF is essential: while PostScript serves as a programming language for controlling printers, PDF functions as a page description language focused on the final appearance of the document. Essentially, a PostScript file can be viewed as a set of instructions for a Raster Image Processor (RIP), while a PDF is akin to a compiled output of those instructions.

With the release of PDF 1.4 in 2001, new features such as layers and transparency were introduced, setting PDFs apart from their PostScript predecessors. As time has progressed, the PDF format has become dominant, while PostScript is gradually fading into the background.

Within the technical framework, a PostScript file resembles a Forth program, beginning with a comment that identifies it as a PostScript file, followed by a prologue defining functions and fonts. The main body employs commands like 'moveto' and 'lineto' to construct paths for rendering. Notably, PostScript supports loops and conditionals, demonstrating its Turing-completeness. At the end of each page, a trailer typically contains a command to render the page.

Conversely, a PDF file starts with a similar comment but includes a body composed of objects that reference pages and embedded resources. This structure also features a cross-reference table and a trailer that directs to the root object, forming the complete document without any code execution in its basic form.

Anyone interested in experimenting with PostScript can do so if their printer supports it, or they can utilize printer drivers. For those looking to delve deeper, GhostScript offers a platform for writing PostScript programs, while GSView allows for rendering and printing capabilities. Notably, PostScript can also be used to generate PDF files.

For instance, a simple PostScript command could create a square, a circle, and text centered within the circle, showcasing the languages capabilities:

%!PS% Draw square100 100 moveto100 0 rlineto0 100 rlineto-100 0 rlinetoclosepath stroke% Draw circle150 150 50 0 360 arc stroke% Draw text "Hackaday" centered in the circle/Times-Roman findfont 12 scalefont setfont(Hackaday) dup stringwidth pop 2 div 150 exch sub moveto (Hackaday) showshowpage

Those who wish to explore further can refer to comprehensive documentation, reinforcing the notion that PostScript is indeed a programming language, despite some skepticism.