[sytelus]

I am still confused why one needs to produce a document as "program" as opposed to set of pixel to be printed. If we know the page size in advance (which we do while pressing the print button), I would expect document program rasterizes it and so "print anything" can be achieved pretty simply. Why they needed to invent a new programming language called postscript?

[simonh]

This is basically how a dedicated device driver for a particular printer works, but back then many operating systems like DOS didn’t have a standardised device driver architecture. Each application like Lotus 123 or Word Perfect would need its own driver for each printer.

To get around that you would write a driver that produced output that could be ingested by as many printers as possible. That intermediate output could be an image in theory, but a 300 dpi page image, especially for a whole document, was enormous at the time, far too big to fit in the memory of most computers or even fit on disc even with compression.

A language makes for a very compact, flexible and efficient intermediate format. Back in the 90s I set up a Linux box at work as a print sever, running the Ghostscript open source postscript interpreter, to print to various printers that didn’t natively support postscript. That was my first use of Linux.

[danachow]

Because in the good old days you expected to share an expensive page printer with many, and it made sense to put a powerful embedded computer (for the time) to do rasterizing within it. It could save on bandwidth, RAM, and storage. The RAM requirements for rasterizing a page would be quite costly at the time.

[andybak]

Rasterize for what?

A plotter doesn't need rasterization.

If you're printing colour offset then the halftone grid would probably use a different rasterization to the one that you want to use for an inkjet or dot-matrix.

"Rasterization" if needed at all probably needs intimate knowledge of the printing hardware.

[hamburglar]

Part of the point was that it was device independent, and simple rasterization wasn’t practical for printing on both low end office printers and the highest end commercial printing imagesetters.

[mongol]

I regularily have to print some specific pdf files that fail to print on my Epson printer. The workaround I found was to rasterize them with ImageMagick, because then they print. But so slow.... It is not an efficient approach.

[pfortuny]

Plotters were much more common those days, also.